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Offshore Design Manual
Offshore Design Manual
FOREWORD
It gives me great pleasure in presenting this manual on the designing aspects considered in the
construction and commissioning of offshore facilities.
This first time effort by the Offshore Design Section has efficiently covered the various design
considerations that are essential in constructing offshore facilities. This design manual provides
adequate data and references to carry out Basic Engineering of offshore facilities and may serve
as a comprehensive guide to any new incumbent in the Offshore Design Section.
The effort put in by the Offshore Design Section in the preparation of this manual is
commendable. The Offshore Design Section shall on a regular basis, revise this manual and keep
it up-to-date with the designing aspects actually being followed by the Offshore Design Section.
(Mr. I. B. Raina)
(ED – CES)
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Offshore Design Manual
PREFACE
The Offshore Design Section is a division that provides in-house engineering to the Offshore
Works Section in the design and construction of offshore facilities. It has been a constant
endeavour of the Offshore Design Section to design minimum-facility offshore platforms in line
with International standards and practices, to help exploit the offshore potential of oil and gas at
optimum cost. The Offshore Design Section has realized these efforts by constantly reviewing
and revising the Design Philosophy adopted in the design and development of offshore
platforms.
This manual provides guidelines for Basic Engineering of offshore platforms and chronicles the
various phases of development in the designing aspects, from the initial EIL-developed design
criteria followed at the time of inception of the section, to the design criteria currently being
adopted by the Offshore Design Section. This manual provides detailed descriptions of the
essential design considerations followed by various disciplines of the Offshore Design Section
and also covers safety considerations in designing offshore facilities.
This manual when used in conjunction with the Safety Manual, the ISO Manual and the
Functional Specifications can provide all necessary inputs to make a functionally complete
technical bid package for construction of offshore platforms and pipelines.
Advice and comments from the readers are welcome, and the same shall be taken care of in the
future revisions of this document.
(Mr. R. K. Marya)
(Head – Offshore Design Section)
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Offshore Design Manual
1.0
INTRODUCTION:
This manual contains information on the Basic Engineering activities related to design of
offshore platforms. This manual captures in one place all the design aspects considered
in the design of offshore platforms.
The intention of this manual is:
• To provide guidelines for Basic Engineering (i.e. bid package preparation) of offshore
platforms
• To provide guidelines on the essential considerations to be borne in mind while
generating design documents for offshore platforms
This manual is to be used by the employees of Offshore Design Section, ONGC and other
persons so authorized by the Chief Engineering Services. This manual shall be used as a
reference document during Basic Engineering of offshore platforms together with the
Safety Manual and ISO Manual prepared by the Offshore Design Section.
This manual spans the changes that the Design Criteria has undergone from the time of
inception of the erstwhile Engineering and Construction Division in 1992 to its evolution
as Offshore Design Section in 2001. A brief description of the constituents of a bid
package is covered in this manual.
This is followed by detailed description of the essential design considerations of
individual disciplines, including a description on safety considerations in designing
offshore platforms. The codes & standards applicable in the design of offshore facilities
have been covered appropriately in the design guidelines of various disciplines.
2.0
HISTORY OF THE OFFSHORE DESIGN SECTION (ODS):
In 1974, with the discovery of the Bombay High field, ONGC entered into a new era of
exploration and exploitation of hydrocarbons. It called for creating an infrastructure and
facilities for oil and gas field development. The Engineering & Construction (E&C)
division was then set up to carryout engineering and construction activities of offshore
projects.
At the time of its inception, the E&C division primarily handled Project Management,
with engineering activities being executed by reputed engineering consultants such as
Lummus Crest Engineering, Snam Progetti and Engineers India Limited (EIL).
Subsequently, a separate section called the Engineering & Planning (E&P) Division was
created under the E&C division for conceptualization of schemes, preparation of
Conceptual Study Report (CSR), review of basic engineering during bid package
preparation and review during detailed engineering and for undertaking engineering
studies. While E&P took care of the above-mentioned project related activities, other
aspects of the project such as Basic Engineering, preparation of bid package, Detailed
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Offshore Design Manual
Engineering, Yard supervision, installation and commissioning were handled by E&C’s
consultant, M/s EIL.
During the year 1984-85, E&P took up engineering for conversion of Jack-up drilling rig
“Sagar Vikas” into an Early Production System (EPS) Sagar Laxmi with back-up from
CFP TOTAL. Subsequently, in 1990-91 when there was a spurt of development schemes
requiring the establishment of 4 process platforms (SHG, NQP, NLP/NLW & SHW) and
13 well head platforms (L-ABCDE, I-MNTWPQS). M/s. EIL expressed their inability to
provide consultancy for all these projects in the required time, owing to the enormity of
the task. The E&P division was therefore required to undertake the engineering activities
in addition to project management activities. This marked the beginning of E&P’s inhouse consultancy service for design and construction of offshore platforms.
During the initial stages of transformation of E&P as in-house consultants, the division
engaged M/s TRIUNE Pvt. Ltd., New Delhi, as back-up consultants to assist the E&P
division in its first engineering consultancy venture - the I-MNTW Project. The basic
engineering documents for this project were adopted from the specifications prepared by
M/s EIL for similar projects.
From the time of its foray into in-house consultancy services, the E&P division has
provided in-house engineering consultancy services for numerous project related to new
platforms, modification of existing platforms, submarine pipelines and clamp-on projects
as independent consultant, without any back-up.
In 2001, E & P division for the first time took up the consultancy of a process platform
project (MNW) – a single largest component of Mumbai High North Redevelopment
Scheme. The MNW process platform project being the first platform project to be
engineered by E&P, it was felt necessary to employ back-up consultants having adequate
experience in engineering process platforms. M/s Worley, Australia were therefore
engaged to assist in some of the critical specialty areas (viz. Common FGC Skid, Gas
stripping based De-oxygenation system, Living Quarter & structural study, etc.) and to
review the bid package for optimization of cost / schedule of MNW Project, participation
in the pre-bid conference, review of techno-commercial bid, etc.
In 2002, under the Corporate Rejuvenation Campaign (CRC), the E&P Division was
renamed as Offshore Design Section and it continues to provide efficient in-house
engineering consultancy.
3.0
EVOLUTION OF ENGINEERING BASIS:
The foremost activity in the design of offshore platforms is identifying the quantum of
work to be executed and finalizing the facilities to be erected and commissioned. These
details are compiled to form a bid package which is then issued to prospective
contractors. The bid package is prepared on the basis of the Feasibility Report on the
project.
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Preparation of the bid package is done following approved ISO procedures (compiled by
the Offshore Design Section in the form of an ISO Manual) together with inputs from
this Design Manual, approved Safety Manual and various Functional Specifications, as
well as suggestions / recommendations received from the Operations Group and
recognized Engineering Consultants from time-to-time.
(Note: An extract of the Safety Manual and the ISO Manual is given in clause 5.1 and 6.0
respectively of this document)
The bid package includes the Scope of Work of the project, the Design Criteria of various
disciplines and the Functional Specifications of various equipment and systems
envisaged on the platform.
The Scope of Work describes the quantum and quality of work that is to be carried out.
The Scope of Work is unique to every project and is the first document that is prepared
when a project commences. (This manual does not cover the basis of finalization of scope of
work of a project).
The Design Criteria, which plays a pivotal role in the design and development of the
offshore facilities, specifies the essential considerations in the design, procurement,
fabrication, transportation, installation, pre-commissioning and commissioning of
offshore platforms. It has been a constant endeavour of the Offshore Design Section to
improve the design criteria by ensuring that the philosophy adopted reduces platform
complexity and cost. (This manual covers in detail the design criteria adopted by various
disciplines of the Offshore Design Section in the design of offshore facilities).
The Functional Specifications describe the specific functional requirements of various
equipment and systems envisaged under the Scope of Work of the project. (This manual
does not include the design details covered in the Functional Specifications of different equipments
and systems).
The bid package documents, including the design criteria, used to be generated by EIL in
the early 80’s and these were very elaborate and prescriptive. It advocated the use of
exotic materials of construction and set higher safety limits, perhaps for achieving higher
level of reliability. These additional reliability margins, however, considerably increased
the cost, the execution time and the platform complexity. Owing to these, the necessity
for optimization was increasingly felt. Therefore, in 1990, an effort was made towards
optimization of cost and facilities, simplification and standardization of equipment /
systems and deletion of supplementary equipment.
These efforts resulted in a Phase-Wise Optimization process which has help achieve cost
optimization by reducing structural tonnage, reducing size of equipment, deleting
supplementary equipment and adopting new technology. The outcome of this
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Offshore Design Manual
optimization process has been the establishment of Minimum-Facility Offshore
Platforms.
Details of the Phase-Wise Optimization process has been covered in section 3.1 of this
manual and the constituents of Minimum-Facility Offshore Platforms (both manned and
unmanned) have been covered in section 3.2 of this manual.
3.1
PHASE WISE OPTIMIZATIONS:
As mentioned in section 3.0 above, the phase-wise optimization process was carried out
to achieve cost optimization by reducing structural tonnage, reducing size of equipment,
deleting supplementary equipment and adopting new technology. The details of the
optimizations carried out (with respect to well-head platforms) are as follows:
•
PHASE I:
During Phase I of the optimization process, certain items, which previously formed a
part of well platforms, were deleted and the capacity of certain other items were
reduced. Details of the same are as follows:
a)
Deletion of items:
The following items were deleted:
Æ Chemical Storage Tank and Chemical Injection Pumps
Æ U/V Sterilizers
Æ Potable Water Tank
Æ Salt Water Tank
Æ Bunk House
Æ Oxygen Scavengers and Bactericide Injection Pump
Æ Monorail
b)
Reduction in Capacity:
Item
Change in capacity
Crude Condensate Drum
Sized for 7 days instead of 15 days
Instt Gas Drier
Reduction in size
Test Separator
Sized for 2500 BOPD instead of 5000
BOPD
Diesel Generator Set
Reduced to 37 KW from 55 KW
Emergency Battery
LT Switch Gear
Reduced to 3000 AR from 4500 AR
Reduced to 100 A from 200 A
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•
PHASE II:
Phase II of optimization activities began in December 1989 and a report on these
activities was submitted in March 1990. This phase of optimization resulted in 250
m2 reduction of platform area and a reduction in structural steel tonnage of
approximately 100 t. The total cost saving through this optimization process was
approximately Rs. 31.5 million / platform.
The items deleted during this phase include:
Æ Sump Caisson
Æ I/U Air Compressor in Platform (which is presently sweet)
Æ Space for Future Launcher / Receiver
Æ Nitrogen Back – up for instrument
Æ Air and Fire Water Pump Start – Up
Æ FQS in Gas Lift Instrumentation (flow Totalizer)
•
PHASE III:
Phase III of optimization activities began in January 1990 and a report was submitted
in May 1990. This resulted in a cost saving of Rs. 28 million / platform.
The details of the reduction in capacity of items during phase III are as follows:
Item
Change in capacity
Crude Condensate Drum
Reduced to 2 m3 from 10 m3
Diesel Storage Tank
Capacity reduced to 2 m3 from 10 m3.
Crude Condensate Pump
Capacity reduced to 300 l/h
Instrumentation
Number of RTU reduced to half
Fire Water Pump
Capacity reduced to325 m3/h from 450 m3h.
Gas Detectors (HC & H2S)
Number reduced to 13 and 12 from 25 each.
DG Set
Capacity reduced to 10 KW from 37 KW.
Emergency Battery & Battery
Charger
Capacity reduced to 1500 Ah from 3000Ah.
Gas Detection Battery, Battery
Charger & Solar Panel
60% reduced for sweet fields, 30% reduced for
sour fields.
Platform Lighting
Load reduction in lighting to 7 KW, 8 KW from
17 KW, 18 KW.
LT Switch Gear
Rating reduced to 25 A from 100 A.
Fire Wall in WH Area
Replaced by steel isolating wall.
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Offshore Design Manual
Test Separator
•
Capacity changed to 3000 BLPD.
PHASE IV:
Phase IV of optimization activities were carried out in 1999 and involved the
implementation of cost optimization recommended by M/s Worley, Australia in ZA
Well Platform Project and MNW Process Platform Project.
a.
Implementation of cost optimization recommended by M/s Worley in ZA
Well Platform Project:
Based on the recommendations of M/s Worley the ZA Well Platform design
criteria were suitably modified to minimize electrical loads. This included
optimization of RTU and Gas Detection Systems. Further, 2-phase test separator
with water-cut meter was used in place of 3-phase separator.
b.
Implementation of cost optimization recommended by M/s Worley in MNW
Process Platform Project:
As mentioned earlier, the MNW Process Platform Project under Mumbai High
North Redevelopment Scheme, is the first process platform for which Offshore
Design Section has taken up consultancy. The MNW Process Platform being a
first time venture, it was felt necessary to have M/s. Worley, Australia, as backup consultant to assist in some of the critical specialty areas (viz. Common FGC
Skid, Gas stripping based De-oxygenation system, Living Quarter & structural
study, etc.) during Detailed Engineering phase of this project. M/s Worley were
also engaged to review the bid package of MNW Platform and suggest suitable
cost and schedule optimization of the project. M/s Worley also participated in
the pre-bid conference and reviewed the techno-commercial bid and has given
valuable suggestions to improvise the bid documents. The suggestions have
been incorporated in the MNW project. The Offshore Design Section shall also
take care of these aspects during the design of future facilities.
•
PHASE V:
Phase V of optimization activities began in 2001 and involved the adoption of CRINE
(Cost Reduction Initiative for the New Era) Concept by the Offshore Design Section.
The adoption of the CRINE Concept was aimed at cost effective development and
application of new technology.
The CRINE Concept primarily recommends the following:
Æ Use of standard equipment
Æ Use Functional Specifications
Æ Determine documentation requirement based on criticality
Æ Simplify / Clarify contract language avoiding adversarial clauses
Æ Rationalize regulations on Certification
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Æ Make quality qualifications more credible
The Offshore Design Division has introduced the CRINE Concept in the N-11 & N-12
Well Platform Project in Mumbai High North field. The methodology for the
implementation of the CRINE Concept in this project, reflected in the technical bid
document, was as under:
Æ Adoption of Functional Specification
Æ Flexibility in selection of material as per code and service, e.g. NACE piping,
etc.
Æ Rationalization of Documentation requirement
The benefits envisaged / derived through the introduction of Functional
Specifications are:
Æ Bidders have been given due flexibility to propose industry-proven
conceptual design and equipment for the well platform in line with the
Company’s requirements. This would introduce the Company to new
designs and layouts that would enable reduction in tonnage and hence in
cost.
Æ There has been a considerable reduction in volume of the Bid Package, owing
to deletion of descriptive items in the bids.
3.2
DEVELOPMENT OF MINIMUM FACILITY OFFSHORE PLATFORMS
The continuous refinement of the Design Philosophy has helped realize minimum facility
offshore platforms. A list of these typical facilities (on manned and unmanned
platforms) is indicated below. The facilities mentioned are indicative only. The same
may vary as per the specific requirements of the project.
3.2.1
Typical Facilities on Manned Platforms:
Manned platforms may broadly be classified as Process Platforms and Water Injection
Platforms. The manned platforms in general have the following facilities:
Æ Six / Eight legged jacket complete with piles, Cathodic protection and monitoring
system, barge bumpers, walk-ways, boat landing etc.
Æ Two level deck structure (viz. cellar& main deck) including helideck and boat landing
facilities with walkways, stairways, ladders, railings etc.
Æ Launchers/Receivers
Æ Marine growth prevention system in jacket members and conductors up to an
elevation of 30.00 m for still water level
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Æ Complete system for sampling and on-line monitoring of Chlorination, Filtration, Deoxygenation, Biological treatment and Corrosion etc.
Æ Deck drain system including a closed hydrocarbon drain system
Æ Living accommodation to cater for the living, messing, recreational and other needs of
the personnel manning the platform offshore.
Æ Utility Water System, Potable Water System, Sewage Treatment System
Æ Fire/Gas Detection and Alarm system complete with detectors for hydrocarbon gas
and hydrogen, Ultra Violet detectors, smoke detectors and thermal detectors
Æ Fire Suppression System consisting of diesel engine driven fire water pump(s), fire
water distribution system and spray network, FM-200 extinguishing system,
firewater and foam hose reels, portable CO2 extinguishers, dry chemical fire fighting
systems etc.
Æ Fuel Gas Conditioning System comprising of gas scrubber, filter, pre-heater, super
heater etc.
Æ Start-up Air System consisting of starting air compressor, air receivers etc
Æ Material handling facilities comprising pedestal mounted diesel operated deck cranes,
electrically operated monorail hoists, pneumatically operated portable hoists,
manually operated trolley mounted chain pulley blocks, hook mounted chain pulley
blocks, drum racks, handling and storage space etc.
Æ Switchgear Building Module comprising of Turbine Generator sets, transformers,
Switch gear, etc.
Æ HVAC or AHU equipment
Æ Helideck, suitable for landing and take-off of Russian MI- 8 Sikorsky S-61 and similar
helicopters, to be installed on top of the LQ module, along with refueling facility
Æ Radio room
Æ Electrical Power Distribution System comprising H.T. & L.T.
Switchgear,
Transformers and Distribution Boards, Control Stations, Junction boxes etc
Æ Un-interrupted Power Supply System, Battery Banks and Battery Chargers
Æ Multi-channel Radio System, Paging and Intercommunication System and Private
Automatic-Exchange Telephone System
Æ Closed circuit television (CCTV) System
Æ Electrical Normal Lighting System and Emergency Lighting System
Æ Navigation Aids and Aviation Marker Lighting Systems.
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Æ Cathodic Protection with monitoring system
Æ Grounding System
Æ Heat tracing system
Æ One Diesel Engine-driven Generator with complete control system
Æ All Instrumentation and Safety System including Control Panels, Shut-down Panels,
Fire/Gas Panel, ESD/FSD System, RTU System, DCS etc
Æ All materials related to interconnecting/piping, wiring, tubing, pipe supports, riser
supports, pipeline supports, cable/trays supports etc
Æ Life Support and Safety Systems comprising Survival Crafts, Life Rafts, Life Ring
Buoys, Life Preservers, Scramble nets and personnel baskets, First-Aid Kit etc.
Æ Safety showers and Eye washers in chemical storage and handling area
Æ All Process, Utility, Service and Miscellaneous piping systems comprising pipes,
specialty items and fittings of different class, materials, specifications etc.
Æ Fire Walls
3.2.1.1 Typical Facilities on Process Platforms:
In addition to the facilities listed in clause 3.2.1, the typical facilities provided on a
Process platform are as follows:
Æ Production Manifold
Æ High Pressure Separators, Low Pressure Separators & Surge Tanks
Æ Pumping facilities for transporting partially or fully stabilized oil through trunk
pipeline or through SBM tanker to shore
Æ PGC module comprising of gas turbine driven process gas compressor with associated
system
Æ Gas dehydration system using T.E.G
Æ Very low pressure gas venting system
Æ HP and LP flare gas system
Æ Hydrocarbon sump tank, sump pumps
Æ Instrument and Utility Air System
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Æ Produced Water Conditioning System
Æ Power generation using Gas Turbine or Emergency generator using Diesel
Æ Diesel Fuel System complete with diesel storage facilities, diesel filter coalesces,
centrifuge separator, diesel transfer pumps etc.
3.2.1.2 Typical Facilities on Water Injection Platforms:
In addition to the facilities listed in clause 3.2.1, the typical facilities provided on a Water
Injection platform are as follows:
Æ Sea Water Chlorination System comprising electrolyte type Sodium Hypo-chlorite
generators complete with filters, electrolytic cells, hydrogen removal system, air
blowers, thyristor controlled power unit etc.
Æ Skid mounted Fine Filters Package
Æ Skid mounted De-oxygenation Tower Package comprising vacuum de-oxygenation
tower in two stage packed-bed design complete with electric motor driven vacuum
pumps, ejectors etc.
Æ Skid mounted Chemical Injection Package complete with storage and dosing system
for the chemicals
Æ Skid mounted Solution Tank and mixers and pneumatically operated chemicals
unloading pumps complete with drive motors, coagulant solution tanks,
polyelectrolyte solution tank, mixers etc.
Æ Skid mounted electric motor driven sea water lift, Booster Pumps, Main Injection
Pumps (only at Water injection facility)
3.2.2
Typical Facilities on Unmanned Platforms:
The typical facilities on unmanned offshore platforms are as follows:
Æ Jacket (sub-structure) complete with piles, cathodic protection without monitoring
system, well conductors, boat landing, barge bumpers, walkways, riser protector,
pre-installed risers etc.
Æ Super-structure comprising of main (drilling) deck, spider deck cellar deck, and
helideck with walkways, stairways, ladders, railings, rub strips etc.
Æ Building module housing the switchgear, battery bank, telemetry, shelter room etc
Æ Helideck suitable for use by Bell 212, Bell 412, Westland WG 30, Sikorsky 576A
(Type-I and Type-II), Dauphin 2 SA 365N type helicopters etc
Æ Production manifold with associated piping, instrumentation with two headers Production header and Test header
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Æ Well testing facilities consisting of Three / Two-Phase Test Separator or multiphase meter complete with shutdown panel, safety controls system etc.
Æ Pipe Separator to supply gas (from prod. header) to OCI Storage Vessel and IUG
system.
Æ Instrument Gas System utilizing the lift gas and complete with pressure reduction
system, gas filter-separator, strap heater, instrument gas receiver and headers.
Æ Utility Gas System (for gas driven OCI transfer pump and blow down of crude
condensate drum)
Æ Chemical Injection System to inject Oil Corrosion Inhibitor in production manifold
(prod. header and test header) and departing well fluid pipeline.
Æ Crude / Condensate Storage and Transfer System based upon blow case design
Æ Open Deck Drain (ODD) System and Closed Hydrocarbon Drain (CHD) System.
Æ Low Pressure Gas Venting / Relief System comprising vent
pot, flame arrester and vent boom.
header, glycol seal
Æ Material Handling System including a pedestal mounted hydraulic deck crane (15
T), C. P. Blocks, hoists, monorails etc.
Æ Fire Suppression System including firewater spray network, hose reels, portable
CO2 / dry chemical extinguishers etc.
Æ Fire Fighting System comprising of Dry Chemical Powder (DCP) skid, hose reels
etc.
Æ Solar panels with back-up battery bank for catering to the continuous electrical
loads during normal unmanned operation.
Æ Navigational Aids
Æ Launchers / Receivers
Æ Injection Water System
Æ Lift Gas System
Æ Safety devices for hydrocarbon service containing H2S e.g. first aid equipment,
breathing apparatus etc.
Æ Life rafts, life jackets, life rings / buoys and other life saving appliances and
portable medical units for eyewash.
Æ Well / Fire Shutdown Panel
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Æ Instrumentation and Shut-down Systems including ESD/FSD system, interconnecting tubing/ cables etc.
Æ Telemetry and Tele-communication System.
Æ Mechanical Marine Growth Preventor (MGP) on jacket
Æ Cathodic Protection System.
Æ Gas Detection System including strobe light, fixed type HC detectors etc.
Æ Portable H2S & HC gas detectors
3.3
The above deliberations show that from the EIL developed design criteria to the
Functional Specifications based Design Criteria, the Offshore Design Section has
continuously strived to improve and standardize the design aspects of offshore facilities.
The design criteria currently being used for manned and unmanned platforms broadly
outlines the basic requirements for design, engineering, material selection, fabrication
and testing of the facilities. This Design Criteria adequately covers various aspects of
Equipment Layout, Personnel Safety and Safety of facility, pollution prevention,
protection from corrosive environment, preventive maintenance, and platform design life
to ensure a safe, pollution-free and reliable working condition. The design criteria /
design document is generated by following certain established design guidelines and
bearing in mind certain essential design considerations.
3.4
The Design Considerations to be followed while generating design documents are
elaborated in section 4.0 of this manual.
3.5
The Design Guidelines followed by the different disciplines of the Offshore Design
Section for the generation of design documents are detailed in section 5.0 of this manual.
4.0
DESIGN CONSIDERATIONS:
Design considerations are the parameters, which provide necessary guidelines for
generating the design criteria so as to ensure a minimum facility platform that is cost
effective, technically sound and safe for operation.
These considerations may be categorized as General Design Considerations and Specific
Design Considerations. These design consideration are listed below.
4.1
General Design Considerations:
The general design considerations borne in mind while designing facilities for manned as
well as unmanned offshore platforms are as follows:
Æ Planning the facilities based on optimum requirements and arranging production
equipment on offshore structures for safe and efficient operation
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Æ Provision of adequate space around equipment, headers etc. to permit easy access for
maintenance
Æ Provision of crane and lifting points for safe handling of equipment and material
Æ Proper lighting and ventilation of work areas with adequate provisions for
communication between personnel
Æ Design of all facilities in accordance with the latest standards and in compliance with
current government regulations
Æ Proper routing of piping to minimize number of bends, corrosion and erosion and to
provide easy access to functional parts of each piece of equipment
Æ Safety Systems to ensure safety of personnel, environment & facility
Æ Minimizing Capital costs, Operational costs and Maintenance cost by adopting a
design that is cost effective and technically efficient.
4.2
Specific Design Considerations:
The specific design considerations borne in mind while designing facilities for manned as
well as unmanned offshore platforms are as follows:
Æ Personnel, Environment & Facility Safety systems on Offshore Platforms:
The safety of operating personnel is the primary consideration in designing
production facilities. Requirement for means of escape, personnel landings, guards,
rails, life saving appliances etc. as specified in international codes and standards are
followed.
Design Criteria for Provision of Safety Systems (excluding Personnel Protective
Equipments) on an offshore production platform is governed by standard API-RP14C – Recommended Practice for Analysis, Design, Installation, and Testing of Basic
Surface Safety Systems for Offshore Production Platforms.
The Purpose of production platform safety system is to protect Personnel, the
Environment and the Facilities from threats to safety caused by the production
process.
Details of the various safety considerations essential in the design of offshore platforms are
given in clause 5.1 of this document. Also refer Safety Manual for further information on
safety considerations in design of offshore platforms.
Æ Utilities Assessment
Utilities on offshore structures may include potable water, utility water, seawater,
electricity, gas, utility air, sewage treatment, garbage disposal, communication
facilities etc. In planning / designing the utility systems, consideration is given to the
number and type of wells, oil and gas processing facilities, remoteness from shore,
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anticipated production volumes, number of people to be accommodated on the
structure, type of fire fighting system, type of control system and electric power
source etc.
Æ Flare and Emergency Relief Systems
Flare and emergency relief systems associated with process equipment are designed
and located considering the amount of combustibles to be relieved, prevailing winds,
location of other equipment, including rigs, personnel quarters, fresh air intake
systems, helicopter approaches and other factor affecting the safe normal flaring or
emergency relieving of the process fluids and gases.
Æ Pollution Prevention
Designing of offshore production facilities include methods for containment and
proper disposal of any type of contaminants which may include liquids or solids
containing liquid hydrocarbons, relatively high concentrations of caustic or acidic
chemicals, raw sewage, trash and inedible garbage etc.
Æ Corrosion, Erosion and Preventive Maintenance
Preventive maintenance and the control of corrosion and erosion are an integral part
of failure prevention, pollution control and safety. In addition, the conditions viz.
space limitations, the salt air environment, and other special requirements are
considered for offshore platform design and operation.
Æ Communication
The Communication being vital to remotely located offshore sites there exists a scope
for communication equipments in Process Platform technical bid specifications. To
facilitate communication with base office, vessels, helicopter process platforms are
provided with:
•
•
Maritime Mobile Band communication equipment.
Aero Mobile Band communication equipment.
The Equipment for these facilities is installed in Display room / Radio room and are
specified to be capable of remote operation from a distance of approximately 300
meters. Antennae of VHF Aero and VHF marine communication equipment are
installed on the top deck of the living quarters.
Æ Integrity Of Platform For Complete Design Life
The Design Criteria takes into account that the integrity of the platform is maintained
for the complete design life of 25 years
Æ Future Provisions
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Design considerations have to take into account the scope for future provisions like
future Risers and Deck extensions.
Æ Equipment Layout
Development of Equipment Layout primarily considers the following aspects:
•
•
•
•
•
•
•
Safety
Accessibility
Operational convenience
Maintenance
Area optimization
Technical & Engineering requirements
Material handling from boat and also within the platform
Æ Material of Construction
The material of construction of any item / instrument on an offshore platform is
chosen considering its application. In general, the material is so chosen as to protect
the item / instrument from the corrosive process conditions and the erosive
environmental conditions that it is exposed to on the offshore platform.
The materials of construction used for different applications on offshore platforms
are as follows:
•
•
•
•
•
Carbon steel (NACE & NON-NACE): For structural, pipelines and pipelines (Sour &
Non- Sour services
Stainless steel: Piping
Cupronickel: Fire water lines
Monel Piping and pipeline splash zone
Duplex and Super Duplex: Sour service piping (now replaced by CS-NACE)
Details regarding the selection of materials of construction for various offshore
applications are covered in the design guidelines for different disciplines given
under clause 5.0 of this document.
5.0
DESIGN GUIDELINES:
The design guidelines followed by various disciplines in the design of offshore platforms
is detailed below. This includes design guidelines for:
•
•
•
•
•
•
•
Process
Instrumentation
Piping
Mechanical
Structural
Electrical and
Pipeline
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Safety of personnel and of the facility is one of the major concerns during the design of
offshore platforms. These general safety considerations have also been described below.
5.1
GENERAL SAFETY:
As mentioned above, safety of personnel and of the facility is one of the major concerns
during the design of offshore platforms. In an effort to compile at one place, all the safety
aspects considered during the design of offshore platforms a Safety Manual” has been
prepared by the Offshore Design Section.
The Safety Manual is intended to serve as a comprehensive document on offshore safety
considerations and is to be referred to during design of offshore platforms for ensuring
platform and personnel safety. Few of the aspects covered in the Safety Manual are given
below.
The general safety features on offshore platforms include:
♦
Structural Protection:
The structural design ensures that all major load carrying structural elements such as
supports, foundations, etc., which can be damaged by fire, are suitably protected.
The structural design is carried out in such a manner that the effects of accidental
loads (such as fire and explosion) and impact loads (such as collision loads or
dropped objects) are reduced. The primary structure is designed to maintain its load
bearing capacity during any fire for the period required for safe evacuation.
♦
Judicial layout of topside and field complex:
The topside and field complex layout of offshore platforms is planned so that all
areas are arranged in such a way that the consequences of fire and explosion are
minimized. Hazardous equipment is segregated from the frequently manned areas
on the platform. Generally the facilities on the platform are located in such a way
that the higher risk areas are leeward to the prevailing wind direction. This provides
maximum ventilation and also minimizes potential explosion overpressure.
Adequate clearance and accessibility is provided around major items of equipment
for carrying out maintenance.
♦
Pipeline and riser design:
Location of pipelines is designed so as to minimize the potential for dropped objects
to impact the pipelines.
♦
Minimization of potential hydrocarbon release sources:
The design of the production facilities minimizes the number of sources for
hydrocarbon release as low as reasonably practicable. Minimization of potential
hydrocarbon release sources can be achieved by: segregating inventories, isolating
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and blowing down hydrocarbon inventories to minimize the quantity that may be
released and adequate isolation / venting / drainage to enable safe maintenance.
♦
Control of Ignition Sources:
The facility is designed so as to minimize the likelihood of ignition of released
hydrocarbons as far as is reasonably practicable. This is achieved through hazardous
area classification and developing equipment layouts in accordance with API RP 500,
and using equipment suitable to the classified area. Providing maximum practical
separation between flammable materials and known ignition sources also helps
control fire.
♦
Identification of Fire Zones:
Fire zones are identified and designated in accordance with NFPA 72. Each fire zone
is provided with fire detection and protection systems appropriate to the hazards
present within the zone. These fire zones are generally defined by natural
boundaries such as firewalls, solid decks or the extremities of the platform.
♦
Fire and Gas Detection Systems:
The Fire and Gas Detection system detects unwanted accumulation of hydrocarbon,
H2S, H2 or fire and initiates appropriate control action such as initiation of active fire
protection, initiation of shutdowns and / or initiation of alarms.
♦
Emergency Control Systems:
Emergency Control Systems are the safety critical systems that are required to
operate and remain operable on detection of an emergency or an impending
emergency. Such emergency control systems are designed to be fail-safe and have
sufficient redundancy to prevent loss of the system. The Emergency Control Systems
include: Emergency Shutdown Systems, Hydrocarbon Inventory Isolation,
Hydrocarbon Inventory Blowdown, Pipeline and Riser Inventory Isolation,
Navigation Aids and Emergency Lighting.
♦
Fire Control and Mitigation:
Fire Control and Mitigation is achieved by means of passive as well as active fire
protection systems.
Passive fire protection includes:
• Provision of fire divisions, walls and boundaries – penetrations through these
are designed and constructed n order to maintain the fire rating of the division.
• Fire protection of vessels, equipment, shutdown valves, supports for vessels
and of structural steel.
Active fire protection systems are used to contain / reduce the effects of smoke and
radiation and extinguish fires as appropriate. Active fire protection systems include:
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• Water Deluge to cool areas and equipment that may be affected by radiated
heat from a fire and prevent its escalation.
• Portable Water Monitors to support the fixed fire protection systems to cool
process areas and equipment that may be affected by radiated heat from a fire.
• Foam to extinguish pool fires
♦
Explosion Control and Mitigation:
The over pressure and subsequent consequences of a hydrocarbon gas explosion are
controlled by a combination of maximized natural ventilation, optimized module
aspect ratio and optimized equipment layout. Wherever possible, equipment
containing hydrocarbon gas or condensate is located in naturally ventilated areas to
aid dispersion of unburnt gases.
♦
Alarms and Communication Systems:
Alarms – both audio and visual – are provided on offshore platforms to intimate
personnel about the existence of an emergency. An audible General Platform Alarm
(GPA) is provided for annunciation in case of gas or confirmed fire detection. An
audible Abandon Platform Alarm (APA) for annunciation when personnel are
required to abandon the platform. In areas of high background noise, greater than 85
dBA, flashing beacons are used to supplement GPA and APA. Beacons are generally
installed on a two loop system such that if one of the loops fail or is damaged, the
beacons shall continue to function.
♦
Escape and Evacuation:
Escape and evacuation routes are provided to ensure the safe evacuation of
personnel from the platform. The escape routes are designed in line with the NFPA
requirements. At least two separate egress routes are provided from each area. The
primary escape routes are generally located around the perimeter of each working
area. All escape routes are clearly marked so that the personnel can readily follow
them in an emergency. Escape ladders, scramble nets, life rafts, life jackets, lifebuoys,
personnel baskets, and other personnel survival equipment such as smoke hoods,
fireproof gloves, flashlights, etc. are provided to aid the personnel during evacuation.
♦
Protection against Occupational Hazards:
Protection against Occupational Hazards includes the following:
• Fire fighting and rescue equipment
• Breathing apparatus sets
• Stretchers
• Eye wash and safety showers
• First aid kit
• Limitation of noise and vibration
• Protection against hot surface in accordance to API RP 14C
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5.2
PROCESS:
5.2.1
Unmanned Platforms:
In the Mumbai Region (MR), field development is based on mostly platform-completed
wells though, very limited number of sub-sea wells have also been drilled and
completed. These well platforms are normally ’unmanned’ and operators’ intervention is
required normally once in a week or in a fortnight, for carrying out well testing and
maintenance/checking of facilities i.e. utilities, safety system, material handling etc.
Drilling & completion of wells and work-over operations of platform-based wells are
carried out using mobile jack-up rigs as water depth is moderate.
In general, unmanned well platform facilities are supported on 4 legged sub structures
and have 6, 9 or 12 slots for drilling of wells, though monopod/tripod type structure &
16 slots platform have also been installed. The type of platform is planned depending on
the suitability to support minimum facilities requirements. Generally, well testing, water
injection & gas lift facilities are provided on these platforms. However, no processing
facilities are provided on these platforms and oil/gas produced after manifolding is
transported to process platform. Other facilities include utility/instrument air/gas
system, fire & gas detection system with automatic shut down facilities, fire fighting,
material handling, RTU etc. Though these platforms are unmanned, shelter room is also
installed on these unmanned platforms for night stay of operators in case of any
operational emergency.
The well fluid pipelines are sized for a pressure range 300-500 psig (21-35 kg/cm²g) at
well platform end. The arrival pressure at process platform end is considered to be 150
(10.5 kg/cm²g) psig or above. The well head lift gas injection pressure varies in the range
of 1000–1150 psig (70-80 kg/cm²g) and water injection pressure as 1350-1500 psig (95105.5 kg/cm²g). Accordingly, the sub-sea pipelines for lift gas and water injection are
sized.
All the wells are provided with Surface Safety valves (SSV) and Sub-Surface Safety
Valves (SSSV) for automatic closing of wells. Shut down valves have also been installed
on well fluid and gas lift pipelines for isolating the platform in case of abnormalities.
Provision for automatic shut down of platforms has also been provided in case of any
abnormality in operating conditions or if there are any fire or safety hazards.
5.2.2
Process Platforms:
The process platforms have facilities for processing of well fluid gathered from
unmanned platforms. Well fluid is processed for separation of oil, gas and water.
Partially stabilized oil is pumped to shore through trunk pipelines and fully stabilized oil
is transported through tankers.
Separated gas is compressed, dehydrated and
transported to shore after utilizing for gas lift & other internal use such as fuel gas. The
produced water after treatment is discharged into the sea after meeting mandatory
discharge criteria.
Important characteristics of Mumbai High oil are as follows:
API gravity
38.40o
Sp. Gravity
0.833
Pour Point
27oC
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Wax Content
-
14 – 15% by wt.
The specifications of stock tank oil for pumping to refinery (Custody Transfer) are:
Æ Salt content – 22.8 mg/lit (8 P.T.B) Max.
Æ RVP at 100oF – 9 PSIA
Æ BS and W – 1.0% (Max.)
The process platforms have central control rooms, which are manned round the clock for
monitoring process & safety parameters. Any abnormalities in platform operation if any,
are noticed and alarmed immediately and remedial measures are taken, automatically,
and if required, with manual intervention for safety of the platform and to save men &
material. Radio & other communication between Helicopter and marine facilities i.e.
MSV/OSV can be requisitioned as and when required and also in case of any emergency.
The process platforms have living quarters having lodging & boarding facilities for
operating personnel. The operating personnel operate on 14 days on/off pattern having
shift of 12 hours duration for operation / maintenance of the platform.
The process platform decks are generally supported on 6 or 8 legged sub structures with
facilities for processing of well fluid i.e. oil, water & gas separation, gas compression, gas
dehydration, oil pumping, produced water disposal, gas flaring etc. In a process
complex, all the above facilities may not be installed on a single platform but on a
number of platforms, which are bridge connected. This is because of limitation in size of
the platform and also for the fact that the development of field takes place in stages and
facilities are added as and when need arise.
The processing scheme in general consist of gathering of well fluid from number of
remotely located unmanned platforms which is manifolded and then heated wherever
required, to the desired temperature in well fluid heaters before it is subjected for stage
separation. The oil, gas and water are separated in 2 stages under “pressurized mode” of
operation and in 3 stages under “stabilized mode” of operation of the platform. Under
“pressurized mode” of operation, the separated and partially stabilized oil is pumped by
Main Oil Line (MOL) pumps, through trunk pipeline, to shore terminal for further
separation / processing of oil before sending it to refinery. The separated gas from both
the stages is compressed in gas turbine driven compressors and then dehydrated by
using suitable method to reduce the water content of gas to 7 lbs/5lbs per MMSCF. The
dehydrated gas is then sent to shore by trunk pipeline after meeting gas lift requirement
and other platform requirements like fuel gas etc.
Under “stabilized mode” of operation, oil separation is carried out in 3 stages and the
stabilized oil is pumped by crude transfer pumps to SBM for tanker loading or to other
process platform for further transportation to shore through trunk pipeline. The 1st stage
separator gas is compressed and dehydrated and low-pressure gas is flared.
With the passage of time, reservoir pressure had declined, Reservoir Gas Oil Ratio (GOR)
of well fluid decreased and water oil ratio has increased, which has resulted in lower
flowing Tubing Head Pressure (THP). For maintaining / enhancing the production, the
operating pressure of 1st Separator has been reduced to reduce the backpressure on well.
A pipeline network has been evolved for inter platform transportation of 1st stage
separator gas for compressing the excess gas, in case gas production of a platform
complex exceeds gas compression capacity or due to non-availability of compressor
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because of shutdown, etc. This provides flexibility in gas compressor operations and also
reduces the gas flaring from the field.
Excess gas, which cannot be compressed or internally used for platform operations, is
disposed off by flaring and cold venting in case of very low-pressure gas. Two types of
flare headers i.e. high pressure and low-pressure flare headers are installed to collect the
hydrocarbon gases and burnt-off in bridge connected or sub-sea pipe flares. Vent headers
are also installed to collect very low-pressure gases for cold venting at safe locations.
The produced water from different separators and vessels etc. are collected and treated in
produced water conditioners to reduce the oil content in treated water to 48 mgm/lit. or
25 mgm/lit. before water is disposed off into the sea. TPI CPI Units were installed on the
earlier platforms as produced water conditioners. Later on, Dissolved Gas
Flotation/Induced Gas Floatation (DGF/IGF) Units were also installed beside CPI/TPI
Units to reduce the oil content in treated water to 25 mgm/lit. Hydro-cyclone type
produced water conditioning system was installed at NA/BHN platform complex by
replacing old TPI units for treatment of produce water. The treated water is then
disposed off into the sea through sump caisson or over board.
The platforms have been provided with 2 types of deck drain system for collection of
liquid for disposal. Closed drain system collects liquids from various vessels, piping,
equipments and open deck drains system for taking care of rainwater, spillage and vessel
drains etc. The open deck drain system has been further modified to collect rainwater
and liquid hydrocarbons separately.
The utilities and other facilities installed consist of gas turbine driven power generation
system, emergency generators, utilities and instrumentation air system, gas and fire
detection system, fire suppression system, waste heat recovery and hot oil system, water
makers for making potable water, chlorinators, chemical injection system, central control
room, work shop, switch gear room, HVAC system etc. Living quarters are also
provided on the process platforms with boarding and lodging facilities for persons who
operate and maintain process platforms and connected well platforms
The Mumbai High oil is sweet oil i.e. no H2S content. However, there is possibility that
due to water injection in the formation, it may turn sour in future. The well platforms,
process platforms and well fluid pipelines etc. designed earlier, were based upon sweet
oil, however, facilitates being designed now, from Infill Platforms onwards, are based on
230 ppm of H2S in well fluid. As such in a process complex like SH older platform
SHP/SHQ, design was based on sweet oil where as design of new platform like SHG,
which is bridge-connected, is based on 230 ppm in oil.
Sub-sea pipelines were laid connecting well platforms with process platforms for
transportation of well fluid from well platform to process platform and for supplying
injection water and lift gas from WI process platforms and process platforms to well
platform for carrying out Water Injection and gas lift respectively. The pipelines are
provided with pig launchers and receivers for pigging the pipelines. These pipelines
have been designed for maximum pressure to which it may be subjected i.e. Well fluid
line to well shut in pressure and gas lift and W.I. pipelines for maximum pressure from
the source. The pipelines are provided with anti-corrosion coating for protection against
external corrosion and cement concrete coating for stability purpose. Most of the
pipelines are not buried. For the protection against internal corrosion, OCI/GCI
chemicals are injected into the pipelines. To avoid congealing of oil in the pipelines, pour
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point depressor is also injected. Pipelines connecting different process platforms are laid
for transportation of stabilized oil from one platform to another for further transportation
to shore. Low-pressure gas lines are also installed for transporting L.P. gas from one
platform to another, for gas compression and dehydration if gas production exceeds gas
compression capacity at a particular platform.
5.2.3
Water Injection Platforms:
Water Injection Process Platforms are also manned platforms where seawater is
processed to make it suitable for the purpose of injecting into the reservoir. The treated
seawater is pumped at high pressure for injecting into the reservoir through number of
injectors wells. The other facilities installed on manned platforms are power generation,
utility instrument air system, control room, fire and gas detection system, fire fighting
facilities, material handling facilities, living quarters etc.
The processing scheme consists of drawing the raw sea water from a depth of about 30
meters by sea water lift pumps. The raw water is then filtered in coarse filters where 98%
of particles greater than 80-micron size are removed. The water is then subjected to 2nd
stage filtration called ‘Fine Filters’ where suspended solids of size greater than 2-micron
size are removed. The fine filters are vertical, pressure type dual media (Anthracite and
Garnet), down-flow filters. Filter aids like polyelectrolyte and coagulants are added
upstream of fine filters, which help in removing suspended particles from raw seawater.
The fine filters require back washing every 2-3 days for maintaining the proper
functioning. The filtered water is then fed to the De-Oxygenation (DO) tower to remove
dissolved oxygen. The D.O. tower is 2 stage packed column having polypropylene pall
ring packing and operating under vacuum. The vacuum is maintained by Vacuum
pump (water ring type) in 1st stage and atmospheric air motivated ejector in 2nd stage.
De-foamers are added in the water, up-stream of D.O. tower, to reduce foaming
tendency. The D.O. tower is designed to achieve residual oxygen content in the deoxygenated water to maximum 20 ppb. Oxygen scavenger is added in D.O. tower in case
of poor performance of D.O. tower to achieve desired level of oxygen in the water.
The de-oxygenated water pressure from D.O. tower is raised by booster and main
injection pumps to the injection pressure. Chemicals like bactericides, scale inhibitor,
corrosion inhibitor etc. are added, up stream of main injection pumps, before treated
water is pumped by Main Injection pumps to various well platforms for water injection.
All the water injection platforms in Bombay High are bridge connected to some process
platforms. Attempts are made to make them hydrocarbon free and hence living quarters
of a process complex are normally installed there. Power and utilities for WI Platforms
and process platforms have been integrated for optimizing the design. The other major
facilities installed on WI platforms are water makers, chlorinator, utility & instrument air
compressors, fire water pump and diesel generators etc. for the operation at the
platforms
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5.3
INSTRUMENTATION:
The purpose of the instrumentation on an offshore platform is to furnish the required
information and data for monitoring and controlling the process and other systems and
to obtain the desired information at the local control centers and Remote Telemetry
interface Unit (RTU).
The instrumentation design criteria broadly covers the minimum requirements of
instrumentation on a platform. It also covers the design and engineering requirements of
the control system for the platform.
The philosophies applied in the design of platform Instrumentation and related control
systems are enumerated in below.
5.3.1
INSTRUMENT PHILOSOPHY:
5.3.1.1 Field Instruments:
All field instruments connected with well monitoring and control, and all facilities that
are not to be operated from a central control room, are pneumatic except those that are
connected to RTU, which are electronic, SMART type.
All instruments connected to control room and remote unit control panels of related
utility systems are electronic.
For remote control application, remote telemetry, telecontrol and data gathering,
electronic instruments are used.
All final actuation / control device, controlled from Central Control Room (CCR) are in
general be pneumatic Control Valve.
Instrument ranges are selected such that the normal operating point is between 35% and
75% of the instrument total range.
Hand-held Intrinsically Safe calibration / configuration units are provided the platforms
to enable online diagnostics, configuration or calibration of electronic instruments from
any point in the loop.
5.3.1.2 Pneumatic Field Instruments:
The instrument air supply is designed to conform to ISA S7.3 “Quality Standard For
Instrument Air”.
For pneumatic instruments, dry instrument gas / air supply used is generally as follows:
5.5 Kg/cm2 (min.)
7.5 Kg/cm2 (nor.)
10.5 Kg/cm2 (max.)
For pneumatic analog control applications, the actuating signal range is in general 0.2 to
1 Kg/cm2.
For pneumatic on-off applications, the actuating signal is in general 0 or 6.5 Kg/cm2.
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5.3.1.3 Electronic Field Instruments:
All electronic transmitters used are 24 V DC loop-powered type with 4 –20 mA Smart
analog signal. Electronic Transmitters in general have integral LCD display. Where this
is not possible, a separate local loop indicator is provided.
5.3.1.4 Control Room Instrumentation:
All signals to and from the Central Control Room are electronic. The standard analog
signal is 4-20 mA using 2-wire system.
Instruments located on control panels and central control room (CCR) are microprocessor
based.
On platforms with processing facilities, a Distributed Control System (DCS) is provided
for monitoring and controlling the process, and for generating alarms in case of process
upsets.
5.3.1.5 Safety Instrumentation System:
The new platforms are generally provided with the following safety systems:
♦
♦
♦
5.3.2
Emergency Shut Down (ESD) System: The ESD system is pneumatic and it initiates
process shutdown in case of abnormal process condition.
Fire & Gas System: The F&G system initiates Fire Shut Down (FSD) upon detection
of hydrocarbon and/or H2S accumulation or fire.
Manual ESD & FSD Stations: The ESD & FSD stations are provided at all strategic
locations on the platform for manual initiation of ESD and FSD.
All shutdown and alarm switches are “Fail Safe”. Shutdown is actuated by independent
tripping devices with independent tapping points.
INSTRUMENT POWER SYSTEM PHILOSOPHY:
5.3.2.1 Pneumatic Supply:
For pneumatic instruments, dry instrument gas / air supply used is as follows:
5.5 Kg/cm2 (min.)
7.5 Kg/cm2 (nor.)
10.5 Kg/cm2 (max.)
5.3.2.2 Electric Power Supply:
Power supplies for all transmitters, controllers, signal converters, electric system and
components in shutdown system are supplied from uninterruptible power supplies.
Power distribution to each consumer is through proper switch and fuse.
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In general, the following Power Supplies are used for instrumentation and Control:
i.
For Process Platforms: 110V AC + 5%, 50HZ + 1% (UPS) for all instruments
control. However, all components / instruments / system are made suitable
for 110 V + 10% AC, 50 Hz + 3%
ii.
For Process & Well Platforms: 24V DC + 5% Battery Negative earthed for
Platform interlock system, solenoid valves, Fire and Gas system and status
lamp.
5.3.2.3 Instrument Earthing System Philosophy:
Three separate earthing systems are provided:
•
•
•
5.3.3
Electrical Safety Earth – Bonded to the site structure and utilized for
electrical safety of metal enclosures and chassis on all instruments and
electrical components.
Instrument Clean Earth – Insulated from the site structure and other metal
work, utilized for instrument cable screens and bonded to the main electrical
earthing system at a single point.
Intrinsically Safe Earth – Insulated from the site structure and other metal
work, utilized for termination of IS zener barrier earth connections, and
bonded to the main electrical earthing system at a single point.
EQUIPMENT PROTECTION PHILOSOPHY:
5.3.3.1 Environmental Protection:
All instruments / equipment and installation material are selected to be suitable for the
overall climatic conditions, the position within the installation and the local environment,
with particular attention to site ambient conditions. The conditions include exposure to
Hydrocarbons, H2S (in case the process fluid is sour), moist salt laden atmosphere, sea
spray, sunlight, monsoon rainfall, temperature, humidity, wind, fungal growth, vibration
and shock, EMI and RFI. All equipment is designed to withstand these conditions
during shipment, storage and installation prior to commissioning. Instrumentation is
designed to withstand not only the quoted environmental conditions, but also the
periodic testing of the Deluge or Fire Hose System.
As all of the offshore sites are subject to seismic activity, all instrument / electrical
frames, panel and racks are securely fixed in position.
In view of the highly corrosive ambient conditions, all internal and external parts which
are not inherently corrosion resistant by choice of material are prepared and finished by
plating or paint finish in accordance with the General Specification for protective coating,
which forms a part of the bid document. Seals and purges are used as necessary, to
ensure reliable instrument performance.
All field instruments are provided with necessary weathering and anti-corrosion
protection. All field instruments are provided with plastic bags (min. 5 mm thick) to
protect them during handling, installation and commissioning. The bags are kept in
place at all times except during work on the devices. Drying agent (desiccant) with
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humidity indicator is put inside the bag and is replaced when color of the indicator
changes from blue to pink Additional protection by other means such as canvas or
leather blankets are provided to prevent damage caused by welding. Labels and tags
that may be exposed to paint spray, are temporarily masked with a transparent material
during construction activities, which are later removed at the time of hand over of the
work. Plastic plugs are fitted to all instrument tubing and air, process and cable entry
ports until final connections are made.
5.3.3.2 Ingress Protection:
All field instruments are designed to have ingress protection to NEMA 4X or IP 66. All
instruments inside pressurized equipment / control rooms are designed to have ingress
protection to IP 42 minimum.
5.3.3.3 Hermetic Sealing:
All relays and switches are hermetically sealed, and those utilized in 24 V DC control
logic circuits have gold plated contacts rated 0.5 Amp at 24 V DC. Those interfacing with
field equipment are rated 2 Amp 24 V DC. All switch contacts are SPDT minimum.
5.3.3.4 Hazardous Area Instrumentation:
Hazardous areas are classified in accordance with API 500 and equipment is specified
accordingly. All instruments mounted outside of normally pressurized control /
equipment rooms require certification by bodies such as FM / UL / BASEEFA / CSA /
DGMS for use in Class I, Division I, Group D, T3 hazardous area, even if the instrument’s
location is classified as a normally non-hazardous area.
Intrinsically safe protection using external barriers are provided for all process
transmitter loops (closed as well as open). Isolating barriers used are of the plug-in type,
mounted on modular back plane termination units. All other instrument loops are
provided with explosion proof / flame proof protection. Solenoid valves, electric hand
switches, signaling lamps and Intercom / Paging system are chosen Explosion proof /
flame proof Ex d to NEMA 7.
5.3.3.5 R F Interference:
All equipment are designed to be unaffected by radio transmissions. Band-pass and / or
band stop filers are fitted, as necessary to ensure immunity to RFI.
5.3.3.6 Sealing:
Seal systems are used to isolate instrument from the process fluid encountered in the
following services:
a)
b)
c)
d)
Wet gas, which may condense in the instrument lines.
Process fluids that vaporize, condense or solidify under operating pressure and
ambient temperature.
Process fluids that will subject the element to high temperature.
Corrosive process conditions.
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e)
Viscous liquids.
Sealing is accomplished with diaphragm seals as well.
All venting instrument and pilot valves are provided with bug screens fitted to
atmospheric vents.
5.3.4
INSTRUMENT MATERIAL SELECTION PHILOSOPHY:
All materials and equipment furnished are required to be new and unused, of current
manufacture and the highest grade and quality available for the required service, and
free of defects. Materials and equipment are adequately protected from construction
damage, particularly damage due to sandblasting and painting.
Materials are selected with regard to the following criteria:
•
•
•
•
•
•
•
•
•
Suitability for the specified process conditions, with SS 316 the minimum for use
outside pressurized rooms, except for salt-water service, which shall be Monel.
Suitability for the corrosive effects of the atmosphere.
Galvanic compatibility between dissimilar materials, with isolating bushes, plates,
used where necessary to prevent corrosion due to galvanic action.
The possibility of selective corrosion in certain alloys and stress corrosion cracking in
certain high strength materials when used in corrosive environments. Where H2S
may be present in process streams, all wetted metallic parts of instruments, valves,
tubing and fittings are required to comply with the requirements of NACE MR 0175,
2002.
Company approval is mandatory for the use of Aluminium for any instrument
component. Use of Aluminium is permissible only if no other suitable material is
available from the manufacturer, and Aluminium is not used for any component in
contact with the process fluid. If Aluminium is used for any housing or component it
should be suitably coated and certified as copper free i.e. less than 0.4% copper by
mass.
Material for all junction boxes, and instrument electronics and termination housings
is in general SS 316.
All spindles, bushings, bolting, screws etc., are required to be manufactured from a
suitable grade of stainless steel. All bolts and screws are required to have a flat 316
SS washer under the nut, and with the thread length such that there is complete full
engagement of the nut, with a minimum of two threads protruding.
All fittings, supports, panels, fasteners, brackets, grider clamps, angle, tube clips,
saddles, channel, U-strut type channel, cable ladder, conduit, cable glands and the
like are made of SS 316.
All material for instrumentation, in contact with process fluid containing CO2 in
excess of 2 Kg/cm2 psi partial pressure, are designed as follows:
Fluid Temperature
< 71 oC
> 71 oC
•
Material to be used
ASTM A182-F316 (316SS)
ASTM A182-F51 (2205 duplex steel)
Moulded polyester parts are required to be anti-static for hazardous area locations,
and in general are constructed from UV-stabilized glass reinforced polyester. Surface
resistance required is not less than 109 Ohms.
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5.3.5
INSTRUMENT INSTALLATION PHILOSOPHY:
The Instrument installation philosophy ensures quality craftsmanship and conformance
to the best applicable engineering practices.
All instruments are installed in a neat workmanlike manner for ease of operation and
maintenance.
The Contractor is required to prepare hook-up and installation details drawing for the
Company’s approval, and all installation are carried out in accordance with these
drawings.
The instrument / equipment are installed only in the approved locations, with due
consideration of the following:
Æ No instrument with the exception of pressure gauges and temperature indicators,
shall be installed in such a way that it depends for support on the impulse piping or
electrical connections to it.
Æ Positioning of equipment shall not constitute a safety hazard. Where possible,
instruments shall be mounted so that they are protected from the effects of rain and
sun, while maintaining the requirements for access and visibility. Where this is not
possible, the Contractor shall provide a fixed cover or hood to protect instruments,
without impairing access or visibility
Æ Visibility and accessibility for both maintenance and operations purpose
Æ Ease of access for lifting heavy items of equipment such as valves
Æ All instruments and valves shall be free from vibration.
Æ Instruments shall be mounted / connected so as not to stress vessel nozzles or pipe
tapping.
Æ Instruments shall be fitted so that they can be removed by a single person.
Æ All local process-connected instruments shall be located as close as possible to the
point of measurement while still being accessible from the deck, ladder or a platform.
Æ Instruments requiring frequent routine access (including hand-valves, manual resets,
manual switches, etc) shall be mounted approximately 1.4m above the deck or
platform.
Æ Instruments shall be properly supported on brackets or mounted on sub-plates, or
placed on a suitable pedestal, pipe stand or structural support. Pipe or structural
stands may be welded directly onto platform plate, with a suitable penetration in the
grating, where applicable.
Æ Instruments, tubing, cables and cable ladder shall not be fixed to gratings or handrails.
Æ Instruments shall not be mounted directly on process piping without the Company’s
written approval.
Æ Instruments or instrument lines shall not be supported on handrails unless approved
by the Company.
Æ Fittings such as instrument isolating valves and instrument air or gas regulators shall
be supported either on the instrument stand or close-coupled to the instrument in a
manner that no undue stress is imposed o the tubing or instrument.
Instrument stands or panels are installed in accordance with the approved drawings,
with consideration for:
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Æ The most direct routes for tubing and piping to and from the stand, using common
tubing runs and avoiding crossovers.
Æ Ease of inter-connections between instruments
Æ Ease of access for on-site calibration and / or removal of instruments
Æ Minimum interference between tubing, piping and cabling to instruments
A 316 SS combination filter regulator with gauge is provided for each instrument
requiring regulated gas or air supply.
5.3.6
INSTRUMENT INSPECTION & TESTING PHILOSOPHY:
General:
The Contractor has to submit a quality plan, which includes a comprehensive fully
documented inspection and testing plan specific to the project.
The procedures include inspection specifically for compliance with hazardous areas
requirements, including current certificate, without which no circuit or loop is energized.
All testing, calibration and pre-commissioning is done by the Contractor. The Contractor
also provides assistance as required in the Company’s commissioning activities.
The Contractor, in the presence of the Company Representative, verifies by inspection,
calibration and loop testing that all instrumentation in field and control room including
local and remote/central control panels is complete and operable. All testing and
calibration are subject to approval of the Company. The Company Representative prior
to shipment checks out panels, consoles, and packaged instrument assemblies.
In addition to yard calibration/testing loop checking and setting for safety devices like
process switches, safety valves etc. and simulation testing of all interlock and shutdown
systems, these activities are also carried out at offshore.
Flushing of Lines:
The Contractor is required to remove in line instruments like flow meter, control
valves/safety valves if necessary and provide spool pieces/flanges prior to flushing of
lines.
Instrument Supply Lines:
Instrument air/gas piping and tubing are disconnected upstream of all filter/regulators
and blown down to remove water, slag and mill scale from lines.
Instrument air/gas tubing and piping are hydrostatically tested. Instrument air supply
lines are blown with instrument air prior to connecting to instruments. Instrument
air/gas mains are isolated from the instrument and pressurized to 11/2 times maximum
working pressure with instrument air. They are then isolated from the pressure source
and the pressure reading on a test gauge is required not to fall by more than one psig in
ten minutes.
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Instrument Signal Lines:
Instrument signal lines are blown with instrument air prior to connecting to instruments.
All air/gas tubing are tested and inspected by one of the methods given in Instrument
System & Automation Society (formerly known as Instrument Society of America)
Recommended Practice RP 7.1 “Pneumatic control circuit pressure test”. Clean, oil free
instrument air is used for the test.
Impulse Lines:
All process impulse lines are disconnected and flushed with potable water. Air lines are
blown down with filtered air. Hydraulic lines are flushed with hydraulic oil.
After flushing, process impulse lines are isolated from the instrument and pressurized
hydraulically to 11/2 times maximum working pressure corrected for ambient
temperature. They are then isolated from the pressure source and the pressure reading
on a test gauge is required not to fall at a rate exceeding one psig/hour.
Direct Mounted Instruments:
For direct mounted instrument such as level gauges, level transmitters (displacer type),
level switches etc, the installations are pressurized to maximum operating pressure
slowly and steadily with the instruments. The installations are then isolated from main
pressure source. The pressure is required not to fall at a rate exceeding one psig/hr.
Wiring:
Wiring is checked to ensure that it is correctly connected and properly grounded.
Insulation test is carried out on all wiring taking necessary precautions. Correct
connections of all electric or pneumatic switches are also checked.
Calibration:
The Contractor’s instrument personnel calibrate the equipment. This calibration when
possible is done with the instrument or system in place, otherwise calibration prior to
installation or removal for calibration is done. The Contractor generally provides written
results of all instrument calibration in prescribed format.
Testing:
In general, all tests simulate, as closely as possible, design process conditions by use of
manometers, potentiometers, deadweight testers, test pressure gauges, etc. utilizing
hydraulic and pneumatic suppliers. Three (3) point calibration refers to the input signal
to an instrument equivalent to 0, 25, 75 and 100 per cent of the instrument range upscale
(rising) and 75, 25 and 0 percent of the instrument range downscale (falling). All
instruments are generally calibrated in upscale and downscale directions and, if
necessary, adjusted until their accuracies conform to those limits stated by the
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manufacturer. Upon completion of these tests, the instruments are drained, the
components removed and the shipping stops replaced.
Reporting:
The Contractor is required to provide written results of all above tests and if required by
the Company, provide reasonable evidence of the satisfactory condition of test
equipment.
All errors of faulty workmanship discovered during this testing are to be corrected to the
satisfaction of the Company
5.3.7
INSTRUMENT SPARES PHILOSOPHY:
For all major equipment, normal commissioning spares are included as a part of the
equipment. The Contractor also furnishes separately, list of recommended spares for two
year’s trouble free operation along with the prices for purchaser’s review.
5.3.8
PHILOSOPHY FOR FUTURE FACILITIES:
Provision is made in all control systems such as control room instrumentation,
pneumatic shutdown panels and local panels etc to operate and control future facilities
shown in P&ID. All panel / cabinet mounted instruments and accessories required for
this purpose are also supplied and installed by the Contractor.
5.3.9
LIST OF CODES & STANDARDS FOLLOWED BY INSTRUMENTATION:
The Codes & Standards followed by the Instrumentation discipline in generating design
documents are as follows:
American Gas Association (AGA)
AGA Report No. 3
Orifice Metering of Natural Gas
AGA Report No. 8
Compressibility and Supercomressibility for Natural Gas and
other Hydrocarbons.
AGA Report No. 9
Measurement of Gas by Multipath Ultrasonic Meters
American National Standards Institute (ANSI)
ANSI B 2.1
Pipe Threads
ANSI B 16.5
Steel Pipe Flanges, Flanged Valves and Fittings
B 16.10
Face to Face and End to End Dimensions of Ferrous Valves
B 16.34
Hydrostatic body and leak testing of isolation valves.
B 16.37
Hydrostatic Testing of Control Valves
B 16.104
Control Valve Leakage
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FCI 70.2
Leak Testing of Control Valves
ANSI C 96.1
Temperature Measurement Thermocouples
ANSI B 1.20.1
Pipe Threads, General Purpose
MC 96.1
Temperature Measurement Thermocouples
American Petroleum Institute (API)
API 6D
Specification for pipeline valves
API 6FA
Fire Test for Valves
API RP 14C
RP for Analysis, Design, Installation and Testing of Basic Surface
Safety Systems on Offshore Production Platforms.
API RP 14F
RP for Design and Installation of Electrical Systems for Offshore
Production Platforms
API RP 14G
RP for Fire Prevention and Control on Open Type Offshore
Production Platforms
API RP 500
Classification of Locations for Electrical Installations at
Petroleum Facilities Classified as Class 1, Division 1 and
Division 2
API RP 520
Sizing, Selection and Installation of Pressure Relieving Devices
in Refineries, Part I and Part II
API RP 521
Guide for Pressure Relief and Depressing Systems
API RP 526
Flanged Steel Safety Relief Valves
API RP 527
Commercial Seat Tightness of Safety Relief valves with Metal to
Metal Seats
API RP 550
Manual on Installation of Refinery Instruments and Control
Systems (out of print)
API RP 551
Process Measurement Instrumentation
API RP 552
Transmission Systems
API RP 554
Process Instruments and Control
API RP 555
Process Analyzers
API 598
Valve Inspection and Testing
API Standard 2000
Venting Atmospheric and Low Pressure Storage Tanks: Nonrefrigerated and Refrigerated.
API 1101
Measurement of Petroleum Liquid Hydrocarbons by Positive
Displacement Meter
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API RP 2001
Fire Protection in Refineries
API 2534
Measurement of Liquid Hydrocarbons by Turbine Meter
Systems
API Manual of Petroleum Measurement
Measurement of Crude Oil by Coriolis Meter
Standards
–
American society of Mechanical Engineers (ASME)
ASME PTC 19.3
Performance Test Code Temperature Measurement
American Society for Testing and Materials (ASTM)
ASTM A269
Stainless Steel Tube
ASTM A276.316L
Stainless Steel Fittings
ASTM 370
Standard Test methods and definitions for Mechanical Testing of
steel products
General Requirements for Carbon, Ferritic Alloy, and Austenitic
Alloy Steel Tubes
ASTM 450
British Standards
BS 1904
Specification for industrial platinum resistance thermometer
sensors
BS 4937
International Thermocouple Reference Tables
BS 5501
Electrical Apparatus for Potentially Explosive Atmospheres
BS EN 60529
Specification for degrees of protection provided by enclosures
(IP) codes
International Electrotechnical Commission (IEC)
IEC STD 801
Part 3 – EMI and RFI Immunity
IEC 60092-373
Shipboard flexible coaxial cables
IEC 60092-359
Specification for insulation and sheath of electric cables
IEC 60227
Polyvinyl chloride insulated cables of rated voltages up to and
including 440/750 V
IEC 60331
Fire resisting characteristics of electric cables
IEC 60332-1
Tests on electric cables under fire conditions Part I: Tests on
single vertical insulated wire or cable
Tests on electric cables under fire conditions Part II: Tests on
single small vertical insulated copper wire or cable
IEC 60332-3
IEC 61508-1-7
Functional safety on electrical / electronic / programmable
electronic safety-related systems
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IEC 61000-4-2
Electromagnetic Compatibility (EMC) – Part 4: Testing and
Measurement Techniques – Section 2: Electrostatic Discharge
Immunity Test
IEC 61000-4-3
Electromagnetic Compatibility (EMC) – Part 4: Testing and
Measurement Techniques – Section 3: Radiated, RadioFrequency, Electromagnetic Field Immunity Test
IEC 61131-3
1993 Programmable Controllers – Part 3: Programming
languages
Institute of Electrical and Electronic Engineers (IEEE)
IEEE STD.472
Surge Withstand Capabilities
IEEE C37.90.1
IEEE 730
Standard Surge Withstand Capability (SWC) Tests for Protective
Relays and Relay Systems
Standard for Software Quality Assurance Plans Revision of IEEE
Std 730-84 and Redesignation of IEEE 730.1-89; IEEE Computer
Society Document
IEEE 828
Standard for Software Configuration of Management Plans
IEEE 1042
Guide to Software Configuration management IEEE Computer
Society Document
Instrumentation Systems and Automation Society (ISA)
ISA 5.1
Instrumentation Symbols and Identification
S 7.0.01
Quality Standard for Instrument Air
ISA/ANSI-S 84.01
Application of Safety Instrumented Systems for the Process
Industry
ISA 912.13
Part I: Performance Requirements, Combustible Gas Detectors
Part II: Installation, Operation and Maintenance of Combustible
Gas Detectors
ISA S 71.01
Environmental Conditions for Process Measurement and
Control Systems: Temperature and Humidity
ISA S 71.04
ISA S 75.01.01
Environmental Conditions for Process Measurement and
Control Systems: Airborne contaminants
Flow equations for sizing control valves
S 75.03
Face to Face Dimensions for Flanged Globe Style Control valves
International Organization for Standardization (ISO)
ISO 5167
Measurement of Fluid Flow by means of Orifice Plates
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National Association of Corrosion Engineers (NACE)
NACE MR 0175
Sulfide Stress Cracking resistant metallic materials for oilfield
equipment
National Electrical Manufacturers Association (NEMA)
NEMA 250
Enclosures for electrical Equipment (1000 Volts maximum)
National Electric Code (NEC)
National Fire Protection Association (NFPA)
NFPA 70
National Electrical Code
NFPA 1
Fire Protection Code
NFPA 72 E
Automatic Fire Detectors
NFPA 496
Standard for Purged and Pressurized Enclosures for Electrical
Equipment
Other Bodies
Report EE170E.98 ER & E Version 1.0, Alarm Management Guidelines
Engineering Equipment Materials Users Association (EEMUA) publication No. 191,
Alarm Systems – a Guide to Design Management and Procurement
5.4
PIPING:
GENERAL:
This refers to the basic requirements of material selection, corrosion philosophy, piping
design parameters to be considered during fabrication, hook-up & pre-commissioning
activities and safety, health & environmental aspects. International codes governing
design are given in clause 6.0 of the manual.
5.4.1
CORROSION PHYLOSOPHY:
Corrosion implications for process components consist of the five process stream
components contributing to the corrosiveness of the fluid are water, carbon dioxide,
hydrogen sulphide, chlorides and organic acids in crude oil. The opposing components
are oil films and any inhibitor additions or scaling chemicals contributed from the
produced water. The Contractor carries out such calculations to demonstrate that the
design life will be achieved.
Free Water:
In piping and vessels filled with liquids, the metal surfaces may be protected by scales
from corrosion products or formation deposits, oil films or deliberately added inhibitor.
Use of carbon steel may be acceptable provided that the combination of corrosion
allowance and inhibited corrosion rate can deliver the design life and that downstream
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contamination by corrosion products is not a concern. In a gas stream after water
separation or after compression, corrosion will only occur if there is produced water
carryover or the gas stream is condensing and there is no other control measure such as
addition of a misting inhibitor. Standard calculations provide the dew point temperature
for given conditions although the dew point temperature predictions are most accurate
on smooth surfaces such as pipes. In crevices or in locations with deposits, condensation
may occur a few degrees below the dew point. The difference in corrosivity between
wetting with potentially scaling produced water and condensation of CO2 saturated
water are to be considered to assess the possible benefits of scaling on corrosion rates.
Carbon dioxide:
CO2 corrosion only occurs when the susceptible metal is wet and is the result of the CO2
reacting with water to form carbonic acid. CO2 corrosion is prevalent as pitting and
mesa type corrosion where water condenses out of the gas phase. CO2 is also prevalent
as general corrosion (often severe) where water gathers or flows even if it is beneath
liquid hydrocarbons. The corrosion mechanism may be self mitigated to some degree
due to the formation of a FeCO3 layer but in the presence of chlorides in the
formation/produced water, the FeCO3 layer will become unstable and will not
satisfactorily slow the corrosion rate. Hence, the severity of CO2 corrosion will depend
both on the temperature and pressure but will also depend on whether the water is
condensed or is formation water that frequently contains scale-forming components,
which reduces the corrosion rate.
Hydrogen sulphide:
Process streams containing hydrogen sulphide may cause sulphide stress cracking of
susceptible materials. The phenomenon is affected by a complex interaction of
parameters including metal chemical composition and hardness, heat treatment, and
microstructure as well as factors such as ph, hydrogen sulphide concentration, stress and
temperature. Material used to contain process stream containing hydrogensulphide are
selected to accommodate these parameter.
The Mumbai high oil is sweet oil i.e. no H2s content. However, there is possibility that
due to water injection in the formation, it may turn sour in future. The well platform,
process platforms and well fluid pipeline etc. designed earlier, were based upon sweet
oil, however, facilitates being designed now, from Infill Platforms onwards are based on
230ppm of H2S in well fluids. As such in a process complex like SH older platform
SHP/SHQ, design was based on sweet oil where as design of new platform like SHG,
which is bridge-connected, is based on 230 ppm H2S in oil.
Chlorides:
Any austenitic stainless steel vessel or pipe work that is internally heated so its external
temperature is above 550C and exposed to the atmosphere is at risk from stress corrosion
cracking unless it is painted or otherwise shielded to prevent chloride concentration on
surface that may be used or carbon steel components that are internally clad with 316L
stainless steel. However, the latter requires additional expertise in welding and
fabrication.
Organic acids:
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No Total Acid Number (TAN) data has been is reported although problems usually arise
at more elevated temperatures than those to which the process stream is heated on this
platform. Nevertheless, this corrosion mechanism requires consideration if carbon steel
is used in contact with water and high TAN oils.
Corrosion Inhibition and Monitoring:
Any inhibitor program is designed around the delivery points and techniques. A watersoluble inhibitor is selected from candidate materials by use of laboratory tests. The
timing of the dosing is selected by persistency trials reinforced by monitoring. In area,
which suffer from condensation but are not adequately wetted with inhibited water,
corrosion can be controlled by mist spraying of inhibitor. The only caveat is that mists do
not travel well around bends unless the flow is sufficiently turbulent. The inhibitor
evaluation includes possible environmental effects of any inhibitor dosing that is
discharged with the extracted water.
The design of the corrosion monitoring includes the three timelines philosophy, i.e. short,
medium and long term monitoring.
The routing process monitoring, which is carried out automatically (with operator
overview) provides the first level of monitoring to ensure that temperatures, pressure
and pressure drops, flow pH and conductivity are within expected limits. If they are not
then the process is to have an incremental response depending on the consequences of
the deviation and its magnitude. This requires sufficient automated instrumentation and
management software/firmware for proper analysis of the data.
The second tier is the regular testing programs where process samples are procured and
analyzed at set intervals. Corrosion coupons or, more probably electrical resistance
probes, are measured regularly. The final tier is the scheduled measurements of residual
wall thickness and general inspection possibly including internal surfaces of vessels
although the risks of process contamination inherent in opening vessels obviously limit
internal inspections.
Note that there has to be external inspection programs that will run in parallel with the
monitoring of the process side.
5.4.2
Utilities and Support Systems:
These include non-corrosive air, possibly corrosion inhibiting and biocide chemicals, oil
treatment chemicals and seawater for fire or deluge control. Heat exchangers are aircooled. Heating oil and the like are not critical as far as internal corrosion is concerned.
5.4.3
Chemical Delivery:
Such systems generally cannot be inhibited and cannot tolerate corrosion products so
they may be assembled from stainless steel. The fluids may include potable water or any
of the emulsion controlling, inhibiting or other chemicals, which are aggressive to carbon
steel. As indicated previously small diameter stainless steel tube may require external
coatings in the tropical marine environment to prevent staining, pitting and possibly
stress corrosion cracking. Whilst it is superficially attractive to specify an improved
surface finish (<0.5umRa) with its enhanced corrosion resistance the probability of
damage during the design life virtually dictates that an external coating is a more
conservative option.
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5.4.4
Sea Water:
If seawater is used for the firewater system then the material choice depends to some
extent on the operating philosophy, i.e. is it recalculating, left dry, left stagnant, etc.
Typically seawater is sterilized by oxidizing compounds and then is held stagnant for
some time. Oxidizing treatments will tend to increase corrosion rates in seawater. The
design must consider whether carbon steel (possibly with an internal coating) or even
316L is adequate or the preferred option of the more resistant materials such as CuNi or
glass reinforced polymer with fire resistant treatments. The 10-year design life is
addressed with plans to control the possible defects arising from fabrication or
subsequent operation.
5.4.5
Bolting:
It is generally not acceptable to use unprotected high strength carbon steel bolts in a
corrosive environment (such a marine exposure) because of the risk of corrosion causing
hydrogen embrittlement. Heavy galvanizing has proven satisfactorily in tropical marine
environments.
The use of stainless steel fasteners has its own difficulties especially if the fasteners are
required to be removed.
Austenitic fasteners tend to gall or cold weld, which often leads to fracture of the
fastener. The problem occurs if the mating surfaces are close in hardness (difference
<50HB) and is worse for surfaces outside the surface roughness range of 0.25 to 1.5um or
if the contact stress is high. It can be reduced if different materials are used, e.g. duplex
nuts and austenitic stainless steel bolts. A second best procedure is to use material for
nut and bolt with the addition of an anti-seize lubricant.
5.4.6
Fire Water And Deluge System:
Injection water are specified for the firewater and deluge system. The system will be
dosed with biocide and will remain stagnant except for the monthly tests required by
NFPA20.
The seawater will be oxygenated on ingestion but may steadily deoxygenate and rise to
ambient temperatures in the pipes
Cathodic protection provided by the bronze components.
5.4.7
Material Selection Philosophy:
This covers the minimum requirements for materials selection for offshore manned &
unmanned Platform. This refers the assessment of material requirements for various
services on offshore platforms for deck piping &, vessels in sweet, sour conditions &
offshore environment. The material selection logic has been based on a design life of 25
years, reservoir data, and environmental data, process simulation information that
provides pressure, Temp & fluid composition for various piping systems. The material of
construction is very critical to designing of oil & gas facility due to varying environment
& handling requirement. During initial stage of development well platforms in offshore
were provided with exotic materials viz. Incoloy, DSS & CS with cladding etc were also
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provided as extra measures of safety with due considerations of H2S & CO2 etc in oil/
gas fluid. Therefore these platforms provided relatively costly due to use of such
materials. Cost optimization exercise & gain in experience in exploitation less costly
materials.
Carbon steel materials are suitable for the majority of the piping system on production
platforms as per API-RP-E.Presence of process streams viz.water, carbondioxide
hydrogen sulphide, Chloride and organic acid as given in 8.3.1 influence material
selection.
However, for hydrocarbon service, material selection is based on the following
considerations:
Æ When the H2S exceeds the limits as prescribed in NACE-MR-0175, CS (Nace) is
selected.
Æ At high temperature, high partial pressure of H2S and CO2, SS(Nace) is selected.
Æ At high temperature, further higher partial pressure and in the presence of chlorides,
more catastrophic stress corrosion cracking can occur. In such cases application of
high alloy stainless steel and nickel alloy as such as Duplex – S.S. are selected.
Æ For seawater services the material selection is based on the following consideration:
Æ For Raw Sea water, Cu-Ni is a suitable material due to high corrosion resistance.
Æ For treated seawater, C.S. is widely used.
Further the material recommendation for various services are presented in the form of
table.
This specification will present information on most commonly used metallurgy for
process piping, firewater, sewage water, drain water, chemical injection services & other
services.
5.4.8
Material Recommendations:
Material Recommendations for various services for piping systems are listed below as
table 4.0 (A) & table 4.0 (B):
TABLE 4.0 (A)
SERVICE
Min CA in mm
Gas Lift
6.0
Well Fluid
Injection Water
6.0
PIPES
FITTINGS
FLANGES
CS (NACE)
CS (NACE)
CS (NACE)
CS (NACE)
CS (NACE)
CS (NACE)
3.0
CS
CS
CS
0.0
GRE (Glass
reinforced Epoxy)
GRE
GRE
Instrument Gas
1.5
SS316L
SS316L
SS316L
Closed Drain
6.0
CS (NACE)
CS (NACE)
CS (NACE)
Produce Water
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Open Drain
3.0
Sea/Saltwater
0.5
Chemical
1.5
CS
90-10 CU-NI
CS
CS
90-10 CU-NI
90-10 CU-NI
SS316L
SS316L
SS316L
0.0
CU
CU
CU
0.0
CPVC
CPVC
CPVC
Sewage
0.0
GRE
GRE
GRE
Acidisation
3.0
CS
CS
CS
Potable Water
(Drinking)
Sodium
Hypo Chlorite
TABLE 4.O (B)
VALVES
SERVICE
BODY
TRIM
Gas Lift
CS (NACE)
ASTM A 182 GRADE F 316L
Well Fluid
CS (NACE)
ASTM A 182 GRADE F 316L
Injection Water
CS
ASTM A 182 GRADE F 316L
Produce Water
CS WITH GRE LINING
ASTM A 182 GRADE F 316L
Instrument Gas
SS316L
SS316L
Closed Drain
CS (NACE)
ASTM A 182 GRADE F 316L
Open Drain
CS
ASTM A 182 GRADE F 316L
Sea/Saltwater
Al-Ni bronze
MONEL
Chemical
SS316L
SS316L
Bronze
Bronze
CPVC
CPVC
Sewage
CS WITH GRE LINING
ASTM A 182 GRADE F 316L
Acidisation
CS
ASTM A 182 GRADE F 316L
Potable Water
(Drinking)
Sodium Hypo
Chlorite
5.4.9
SOUR SERVICE REQUIREMENTS:
All sour service materials conform to NACE Standard MR0175 and so the materials
selected are restricted to those complying with the Standard.
Sour gas service materials are in accordance with NACE Standard MR-01-75. All sour
service material meet the special testing viz. HIC (as per NACE MR O1 77) and inclusion
count check (as per ASTM A45) and as specified below:
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Plate:
ASTM A-516 Grade 70
Forgings:
ASTM A-105
Pipe:
ASTM A-106 Grade B
Fittings:
ASTM A-234 Grade WPB
Flanges:
ASTM A-234 Grade WPB
Valves: Body- ASTM A-234 Grade WPB & Trim- 13% Cr alloy
Bolts:
ASTM A-193 Grade B7M (22 HRC max. hardness)
Nuts:
ASTM A-194 Grade 2M (22 HRC max. hardness)
Copper-based materials are prohibited from use in sour gas service. Stress relieving of
rolled plates, formed heads and pipe fittings is in accordance with NACE Standard
MR0175.
Threaded connections are not permitted on sour gas service.
5.4.10
DESIGN REQUIREMENTS:
All materials conform to project Specification and the identified API, ASME, ASTM, BS
and NACE codes and Standards.
All materials are new & unused. Materials older than one year from the date of
manufacturing are not be accepted.
Design and fabrication conform to this Specification and ASME B31.3, API RP14E & other
applicable codes.
Thickness and material for piping including piping components & specialties items from
reducer of barrel to hanger flange are same as that of riser in splash zone to maintain
constant ID to permit smooth pigging operations.
All cupro-nickel piping are supplied in 20-bar system.
Velocity in Cu-Ni piping does not exceed 1.6 m/sec for 2” NB and below and 3.3 m/sec.
for 3” NB and above. Design of Cu-Ni piping system is to be such as to avoid excessive
turbulence in the system. Monel is used at locations such as bends, reducers,
downstream of restriction orifices, downstream of control valves, downstream of check
valves, etc. wherever there may be a possibility of flow velocities exceeding the limits
given above, impingement of flow stream on piping, or excessive turbulence.
In all cases where Monel is used, it is in the form of spool pieces with electrical isolation
with Cu-Ni material for minimizing galvanic corrosion of Cu-Ni piping.
Wherever dissimilar materials are in contact, sacrificial spool piece of 600 mm or
insulating material is provided to avoid galvanic corrosion.
Pipe work, its supports and anchors, are designed to withstand the results of the
following combinations of loads and forces within the limits of stress set by ASME B31.3:
Æ Hydro-test Condition (The empty weight plus weight of water to fill the piping).
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Æ Operating and Design Conditions (The empty weight plus the weight of operating
fluid)
Æ Wind loading condition
Æ Dynamic Loading Condition
Æ Periodic Site Test Condition
Æ Any other condition that would affect the safety of the pipe work, e.g. cyclic loading
and slug forces, when identified on the Data Sheet
Piping general arrangement drawings/isometrics/support drawings etc. are prepared
using good engineering practices and as per guidelines furnished in project
Specifications.
As good engineering practices, piping in safe area carrying hydrocarbon and
toxic/hazardous chemicals are of continuous lengths with welded joints such that valves,
regulators, flanges etc. are not located in the safe area.
Thermal Insulation are provided wherever required as per P& IDs, and Bid-insulation
Specification. Acoustic insulation, wherever is necessary to limit the piping emitted noise
to the permissible values, follow API standards, and materials used are as per piping
specifications.
Piping schedule/thickness are calculated for each size, service & piping class including
corrosion allowance indicated in material of construction of piping specification as per
ASME B-31.3 for various services based on piping class conditions upto class 900 & actual
design conditions for 1500 class of the system.
All the piping on the bridge between two platforms are designed taking into account the
differential movement of the two structures under extreme (100 years) storm conditions.
Flexibility analysis of the piping system is carried out wherever required by the design
conditions/platform movements and provide necessary loops/supporting arrangement.
The piping connected to equipment is analyzed by the Contractor for flexibility and
maximum stresses developed, along with nozzle reaction on equipment, will not exceed
the permissible limits/values as specified in relevant codes & standards. Vendor data for
maximum permissible nozzle loadings is obtained while analyzing piping for flexibility
analysis. The above permissible limits are not exceeded in any case.
Piping is suitably supported, as necessary, to prevent sagging, mechanical stresses and
vibrations. In general, piping is fastened to pipe racks with appropriate sizes cadmium
plated U bolts (3/8” min.) and is double nutted.
The layout of equipment and piping is based on following principles.
Æ To locate all equipments identified on equipment list.
Æ To comply with standards, regulations, codes, piping specifications and sound
engineering industrial practices.
Æ To maximize safety of personnel, equipment and facilities.
Æ To ensure operatibility & maintainability of equipment.
Æ To provide means of escape & access for fire fighting.
Æ To satisfy all requirements indicated in process documents (P&ID’s)
Æ To minimize shutdown duration.
Æ To provide neat and economical layout, allowing for easy supporting and adequate
flexibility to meet equipment allowable nozzle load.
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5.4.11
DESIGN OF SPECIFIC COMPONENTS:
Pipes:
The pipes are designed as per applicable codes & standards. Piping thickness
calculations are performed as per ASME B 31.3.
Pipe dimensions are in accordance with ASME B36,10 for carbon steel pipe and ASME
B36.19 for stainless steel pipe and BS2871 Part 2 for 90/10 Cu-Ni pipe work up to DN 500
(20”).
Nominal pipe sizes DN 30 (1¼”), DN65 (2½”), DN85 (3½”) and DN 125 (5”) are not used
except where they are required for connections to equipment of standard design or
where specific velocities are to be maintained. When these sizes are used on equipment,
the connecting piping is increased or decreased to standard sizes as close to the
equipment as is practical.
The minimum nominal pipe size is DN20 (¾”) except for air, instrument air, water and
manufacturers’ standard equipment piping.
All nipples are made from pipe as specified in each piping specification.
Carbon steel pipe DN40 (1½”) and smaller used for process lines and other lines carrying
flammable or toxic fluids will have wall thickness at least Schedule 80.
Fittings:
Fittings are used as per the requirement of various fittings like elbows, tees, reducers,
sockolet, weldolets, nipple, swage, couplings, caps, plugs etc. The class of fittings like
ANSI 6000, 3000, 9000 are selected as per ASME B 31.3. The thickness of fittings are same
as that of connected piping.
All unions DN25 (1”) and larger comply with BS 3799.
No straight elbows or threaded bushings are used in piping. Hexagonal bushings (but
no flush bushings) only are used with tubing fittings for connection to instruments, or as
otherwise specifically approved by the Company.
The thickness or reducing fittings match with the wall thickness of the higher schedule
pipe wall. The fitting wall thickness is tapered on a 1:4 gradient to ensure that the
pipefitting wall thickness matches the lower schedule pipe wall.
Seamless fittings are generally used. The only acceptable alternatives are specified in the
Piping Material Specification.
Wrought fittings made from block forging and machined to the required dimensions can
be used only with specific approval from the Company.
All 90º-weld elbows are long radius, unless restricted by available space. If short radius
weld elbows are used, they are de-rated to 80% of the calculated allowable working
pressure if subject to pulsations.
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Fittings are at least the same nominal wall thickness as the pipe to which they attach.
Short radius elbows, which have been de-rated as specified above, may require a wall
thickness greater than that of the connecting pipe.
Welded fittings materials are compatible with the piping material.
Fittings DN40 (1-½”) and smaller are screwed or socket weld except as dictated by
individual material specification classes. Fittings DN50 (2”) and larger are butt welded
except where specified in an individual pipe class Data Sheet.
Mitred joints are not used.
Flanges:
Flanges are in accordance with ASME B16.5 for DN50 to DN600 and with ASME b16.47
Series B for flanges DN650 and larger. They are raised face unless otherwise shown on
the individual vessel data sheets and/or drawings. Non-standard size flanges are
calculated in accordance with ASME Code Rules.
Flanges on 90/10 Cu-Ni pipe work are drilled to ASME B16.5, Class 150#, but be
otherwise compliant with BS4504 Part 2.
API ring joint 5000-psi flanges comply with API 6A.
ASME ring joint (RTJ) flanges have octagonal grooves conforming to ASME B16.5. API
ring joint flanges conform to API specification 6A.
Flanges for orifice plates or spectacle blinds and all RTJ flange assemblies (DN100 (4”)
and larger) are provided with jackscrews (two, 180º apart) in one of each pair of flanges.
The bolt hole pitch circle diameter for orifice flanges DN50, DN80 and DN100 are 1.6 mm
smaller than specified in ASME B16.5.
Flat-face steel flanges are used in cases where piping flanges will mate with valves or
equipment, which have cast or ductile flat face flanges and full-face gaskets used.
Flanges in the piping are kept to a minimum. Flanges are installed only to facilitate
construction, maintenance and inspection and in cases where process conditions dictate.
Spectacle blinds rather than spade blinds are provided where required. Thickness of
blinds is calculated in accordance with ASME B31.3. Pairs of spacers and blinds are used
instead of spectacle blinds of size DN 350 and larger.
Valves:
Valve bodies, seals, etc., are in accordance with the design pressure and design
temperature of the applicable Piping System Specification. Valves may be supplied with
higher design pressure or design temperature trims in order to meet the service
requirements.
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Each valve is supplied with a stainless steel tag, attached to the gland bolting, or hand
wheel, with stainless steel wire, bearing the applicable valve identification, Tag Number
and Purchase Order number.
Ball valves comply with API 6D or BS 5351. All ball valves in hydrocarbon service are
fire-safe in accordance with the requirements of either API 6FA (for trunnion ball valves)
or API 607 (for floating ball valves). Ball valve body patterns are long pattern to ASME
B16.10 Carbon steel, stainless, and alloy ball valves, DN20 (¾”) and larger, are quarterturn design. Soft seals and seats for ball valves are suitable for the maximum applied
differential pressure, the service fluid and the specified pressure and temperature
ratings.
Check valves comply with BS1868 and BS5352. Swing type check valves have bolted
bonnets. Where check valves are placed in vertical runs, valves are equipped with
flapper stops. The stops are not connected to bonnet taps in any way.
Gate valves comply with API 600, 602 or 603 as applicable. Gate and butterfly valves are
used in “clean” non-hydrocarbon services only.
Globe valves comply with BS1873 and BS5352.
Plug valves comply with BS1873 and BS5353.
Steel and alloy valves are designed and tested in accordance with the following: Æ ASME 150# - Designed and examined in accordance with ASME B16.34 and tested in
accordance with API 598.
Æ ASME 300# through ASME 2500# - Designed and tested in accordance with API 6D.
Æ API 2000# through API 5000# - Designed and tested in accordance with API 6A.
All valves with non-metallic seats and seals are fire-safe, tested in accordance with API
607 or API 6FA and certified by an accepted third-party agency.
Valves specified with removable bonnets are of the bolted construction with a minimum
of four (4) bolts.
Gate, globe, angle, ball and check valves are supplied with replacement seats. Where
replaceable seats are not available, the valve seat is stellited and welded into the valve
body.
“LO” (Locked Open) or “LC” (Locked Closed) on drawings is provided with locking
devices. Valves are furnished with the locking tab hardware installed.
Open-ended valves are equipped with threaded plugs or blind flanges.
Full port (as opposed to regular port), ball valves are used where ever specified on the
drawings.
Every block valve is provided with a lever, handle, or hand wheel as necessary to operate
the valve.
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Gear operators are heavy-duty lubricated type and are completely housed in a
weatherproof enclosure.
Socket-weld valves are bolted body or top entry design, allowing removal of seats/seals
for heat protection, prior to welding, without loss of assembly orientation. Single piece
valve bodies, or valves bodies assembled by screwed-together components, are not used
with socket-weld ends.
Valve body thickness, wherever the minimum is not specified the relevant valve
standard, is in accordance with ASME B16.34. All fittings are seamless.
Steel castings for valves are radiographed in accordance with ASME B16.34 Annexure B,
to the following extents:Carbon Steel:
ASME 150#, DN600 or smaller
ASME 150#, DN650 or larger
ASME 300#, DN400 or smaller
ASME 300#, DN450 or larger
ASME 600# and higher
Carbon steel to NACE requirements
Stainless and high alloy steel
Other alloys
10%
100%
10%
100%
100%
100%
100%
100%
Socket-weld-end valves with non-metallic seats or seals are provided with 80mm long
nipples having materials and thickness equivalent to those specified in the relevant pipe
set specifications. These nipples are welded to the valves on both ends before the
packing, seats and seals are fitted. Welded nipples are subject to 100% radiography.
Stem protection is required for all carbon steel gate and globe valves where 13%
Chromium trims are specified. The stems are totally enclosed in sleeves, which are
packed with grease.
(Note: Details of Actuator selection for Valves are covered by the Instrumentation discipline in
Functional Specification No.3700)
Bolting:
Flange bolting are full threaded alloy steel stud bolts, each with two heavy hexagonal
nuts. Stud bolts have full continuous threads and have lengths in accordance with B16.5
with the provision that a minimum of one (1) thread and a maximum of three (3) threads
outside each nut.
Stud bolts are used for all piping closures except where tapped wafer valves dictate the
use of machine bolts.
Branch Connections:
The branch tables are listed. The lists show requirements for branches at 90º angles to the
header. Branch angles less than 90º, but not less than 45º, are allowed, and provided the
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connections are reinforced through the use of circular reinforcing pads or integrally
reinforced branch fittings.
5.4.12
PIPING SYSTEM DESIGN:
Design calculations for pressure/temperature, wall thickness requirements, acoustics,
vibrations, thermal expansion and contraction, pipe weights and flexibility are carried
out in accordance with ASME B31.3 and ASME VIII and API-RP-14E and submitted to
the Company for acceptance.
Piping components are located where they can safely be operated (where necessary) and
maintained. Access is provided to such components, which are located out of reach
from the platform deck. The use of extended hand wheel stems or chain wheels are
avoided.
Dead ends on distribution and collection headers are generally be blind flanged but
where sour or toxic fluids are being carried, spectacle blinds are provided. Where
erosive fluids are being carried, targeted tees are provided.
Long radius bends are generally used, but for pigged lines, 5D bends are required. Short
radius bends are avoided unless essential for clearances. Cold-formed bends are not
permitted. Fabricated mitre bends can only be used on gas turbine exhausts.
5.4.13
PIPE ROUTING:
Piping are routed so as to have the short runs and minimize pipe supports whilst
providing sufficient flexibility for thermal expansion and contraction and mechanical
movement. Expansion and swivel joints are avoided.
Large bore piping are designed to minimize pressure drops. Smaller bore piping are
routed in groups where practical along main pipe racks.
Piping are kept within the deck boundaries.
The number of flanges and unions are minimized. Pipe work carrying hydrocarbons or
other hazardous materials through safe areas do not incorporate flanged connections,
except for those at the associated equipment connections.
Piping are routed to avoid trip and overhead hazards.
Consecutive elbows in different planes are avoided.
Pipe routing allows sufficient space for bolting up flanges or for line-up clamps to be
used for field welds. Refer to 10.5 “Piping Clearances”. Piping routing to ensure that
clear head clearance of 2.3 meter is available on decks.
Piping passing through firewalls are sealed with fire-retarding sleeves.
Primary process and gas connections on piping are DN25 (1”) or larger through the first
block valve.
Primary utility (air, steam and water) connections on piping are DN20 (¾”) or larger
through the first block valve.
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All instrument air and fuel gas connections are from the top of the associated headers.
The angle between any branch and its header is less than 45º.
Scraper tees are provided for lines which are to be pigged wherever branches are larger
than DN50 (2”).
Dimensional rules for piping design are as follows:
Minimum pipe diameter for thermo-well connection on straight run pipe DN 100.
Minimum pipe diameter for thermo-well connection on 90º elbow
Pipe racks to be sized to allow for the future equipment
DN 80
+20%.
Minimum run size of piping in racks
Spacing of instrument air take-offs along pipe rack headers
areas.
DN 50
>3000 mm in process
Minimum slope of HP and LP flare headers
1:100
Minimum slope of open drain header
1:100
Minimum slope of closed drain header
1:100
Minimum slope of pump suction lines where vapour may be present 1:50
5.4.14
PIPE SUPPORTS;
Piping are suitably supported to prevent sagging, mechanical stresses vibrations and
consequent fatigue, while allowing for thermal and structural movement. Piping are
adequately supported for the weight of piping filled with water, with attached
components unsupported, subject to wind, seismic, insulation and any other applicable
loads. The supports prevent excessive stresses in the piping and in the nozzles of the
equipment to which it is connected.
Small bore instrument tubing and piping are adequately supported and protected from
impact damage.
Bracing is provided for small bore branches in piping adjacent to vibrating machinery.
5.4.15
PIPE WAYS:
The piping is routed in either platform north/south or east/west in established pipe
ways. All lines running platform north/south are on different elevation from lines
running platform east/west, as far as practical. A minimum of 600 mm or more
clearance between pipes at the time of changes in elevation of pipe runs in pipe ways to
be ensured.
5.4.16
PIPING CLEARANCE:
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The minimum access clearance for maintenance access shall be 750 mm. The following
design constraints shall also apply.
Minimum height from underside of pipe or insulation to high point of deck level or
platform: 200 mm. Piping routing to ensure head clearance of 2.3 metres is available on
deck.
Control valve arrangement:
Preferred bottom of pipe (BOP) of control valve above deck level or platform: 400 mm
For meter runs, the minimum clearance between BOP and deck is
760 mm
Pipe spacing:
Minimum space between pipes without flanges (after allowing for insulation and lateral
movement): 100 mm
Minimum space between pipes with flanges (largest
allowing for insulation and lateral movement)
100 mm flange to pipe) (after
Minimum distance from pipe to face of steel work (after allowing for insulation): 50 mm
Minimum distance from flange to face of steel work, 50 mm etc.
Valve installations and access:
Preferred height of hand wheel from deck or platform:
Horizontally mounted valves
Vertically mounted valves
1000/1350 mm
1100/1300 mm
Maximum height from local deck or platform level to center line of horizontal hand
wheel without platform (or chain wheel)
Vertically mounted valves (DN100 and larger) 2000 mm
(DN 80 and smaller) 2250 mm
Maintenance or isolation
3000 mm
(Except where temporary platforms can be used and at pipe racks)
Use of chain wheels and extension stems shall be kept to a minimum. Chain shall clear
operating level by: 1000 mm
5.4.17
FLANGED CONNECTIONS:
Flanged connections are minimized, being used only where frequent dismantling is
required, where specific flanged spools are needed, where needed to provide clearances
for equipment removal, or for piping class or material changes.
5.4.18
THREADED PIPE WORK:
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Threaded piping is not used to carry hydrocarbons.
Ping DN40 (1½”) and smaller, when used for services upto 1900 kPag (275 psig), may be
threaded.
Screwed fittings are rated at least 20.7 Mpa (3000 psi).
Bushings, close nipples and street elbows are not used.
Pipe threads conform to ASME B1.20.1.
Cu-Ni pipe work are not threaded. Adapters can be used at valves or equipment.
5.4.19
CHANGES IN MATERIALS:
Where dissimilar piping metals connect, sacrificial pipe spools are provided. These are
of anodic material and at least 600 mm or 3 times the relevant nominal pipe size long,
whichever is greater.
Where this is not practical, electrical insulation joints are provided to prevent galvanic
corrosion.
5.4.20
VENTS, DRAINS AND BLEEDS:
High points on all lines are provided with DN20 (¾”) minimum plugged or flanged
connections for venting during hydrostatic tests. For lines carrying hydrocarbons or
other toxic fluids, the vents are be piped to the nearest vent header.
Low points in lines are provided with drain connections of nominal sizes as follows:Line Size
Drain Size
DN15 (½”)
DN15 (½”)
DN20 (¾”0 TO dn100 (4”) DN20 (¾”)
DN150 (6”) to DN250 (10”) DN25 (1”)
Dn300 (12”) and larger DN25 (1”) to DN 40 (1½”)
Drains on lines other than fire water are provided with valves and plugged. Fire water
drains do not need valves.
All hydro-test vents and drains in hydrocarbon service are DN 20 with valves and steel
plugs unless noted otherwise.
A hydrostatic vent and drain philosophy are developed during detail design and shown
on the isometrics.
5.4.21
CORROSION INHIBITION AND MONITORING PIPE WORK:
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Corrosion monitoring fittings are located as close as practical to the pipe work being
monitored, where servicing access is easy and away from sources of vibration. Clearance
is provided for the removal of the injection quills and monitoring probes motoring
probes, suiting each nozzle orientation and the length of the associated probe. Corrosion
probe nozzles are mounted on the underside of the pipes.
5.4.22
RELIEF VALVES:
Relief valve assemblies are installed in the vertical position, as close to the pressure
source as possible, and are provided with permanent platform access. Relief valves are
bolted directly to vessel and equipment nozzles.
Relief valve piping are designed to withstand reaction forces and moments caused by the
valve discharging.
Piping from relief valves to closed systems slope toward the headers and enter them
from above, or, where that is not practical, have DN20 (¾”) drains in safe areas. Headers
have at least 1:100 slopes toward downstream.
5.4.23
CONTROL VALVES:
Control valves are preferably installed in horizontal lines, with the actuator in the vertical
position. Each valve is located as close as possible to the item of plant under control and
is easily accessible from the deck or permanent platform.
Where control valves are less than line size, reducing spools are made long enough to
permit bolt removal.
Consideration is made for removal or withdrawal of valves or part of valves for
maintenance.
5.4.24
ISOLATIONS:
Piping is designed, so that the connections to equipment and vessels can be isolated for
safe maintenance. This may be accomplished by providing for the insertion of blind
flanges at strategic points or removable spools if blinding is not practical due to line size.
All vessels containing hydrocarbons or other hazardous fluids and which involve
personnel entry during maintenance require such blinds.
Blinds are located so that insertion can be made from the deck or permanent platforms or
access ways. Permanent hook eyes are provided above blinds, which weigh more than
25 kg. Where blinds are not required for isolation, valves are provided for safe isolation.
Double block and bleed isolations are provided where shown on the P & IDs.
5.4.25
CUPRO-NICKEL PIPEWORK:
Cupro-Nickel or Copper-Nickel (Cu-Ni) piping are used for fire water deluge systems.
Fluid velocities in Cu-Ni piping are not to exceed 1.6 m/sec. For DN50 (2”) and smaller
and 3.3 m/sec for DN80 (3”) and larger piping. The piping is designed to minimize
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turbulence. Monel is used where turbulence or impingement are likely – at bends,
reducers and downstream of restriction orifices, control valves, check valves, etc. Monel
piping are in spool pieces and these are electrically isolated from Cu-Ni spools.
Supports for Cu-Ni piping are lined with soft packing pads, neoprene or similar, which
are free of ammonia compounds.
5.4.26
COPPER PIPING:
Copper (Cu) piping are used for potable and other clean water systems. Fluid velocities
in copper piping are not to exceed 1.5 m/sec.
5.4.27
GRE PIPING SYSTEMS:
Glass-Reinforced Epoxy (GRE) or Fibre glass-Reinforced Plastic (FRP) piping are used for
water services where there is little risk of physical impact, typically for overboard lines.
When a GRE pipe penetrates a fire rated wall or floor, the GRE is substituted by a flanged
metallic spool piece, fabricated from a material suitable for the proposed service.
5.4.28
PIPING ON THE BRIDGE:
The design of the piping on the bridge takes into account the differential movement
between the two structures under extreme (100 years) storm conditions and thermal
expansion and contraction. Flexibility analysis of the piping systems is carried out.
5.4.29
PIPING AT THE EQUIPMENT:
Piping at equipment are arranged so the equipment can be removed without the need to
dismantle the equipment, adjacent equipment or piping.
Equipment is not used to anchor piping. Forces transmitted to equipment at tie-in points
is within the Equipment Contractor’s recommended limits.
Piping connected to rotating equipment are designed and supported to minimize the
transmission of vibrations from the machines. The Contractor carries out flexibility
analysis of this pipe work to prevent exceeding allowable nozzle loads as defined by
Contractors of the equipment.
5.4.30
PIPING AT HEAT EXCHANGERS:
Cooling water piping to shell & tube exchangers are arranged so that water does not
drain from the outlet when water supply fails.
Exchanger piping is arranged so that the exchanger can be removed as one unit and so
that the tube bundle can be pulled after disconnecting channel piping.
Piping connections to exchangers are designed and properly aligned to allow for hot &
cold service and to limit the stress on exchanger nozzles to within allowable levels.
Filters are provided in lines to cooling fluid inlets.
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5.4.31
PIPING AT PUMPS:
Piping at pumps are designed and supported so that equipment can be dismantled or
removed with a minimum number of temporary supports and without dismantling
valves and piping other than the spool that connects to the pump. Clearances permit
installation of blind flanges against block valves when the service is hazardous and the
removal of pump rotating elements.
Pump suction lines end with at least four diameters of straight pipe with the same
nominal size as the suction flanges. If reducers are required on suction lines, they are to
be eccentric and installed flat side up.
Recycle lines are provided to allow minimum flows required for pumps.
Pressure relief lines are to be provided for positive displacement pumps.
Valves are located as close as possible to the pump nozzles as practical. Isolation valves
on pump suction lines are full-bore ball type. Isolation valves on discharge lines are
located downstream of check valves.
Pump suction lines in which vapour may be present are inclined downward towards the
pumps with slopes of at least 1:50.
Strainers are provided in all pump suction lines. Permanent Y-type or basket strainers
are provided for reciprocating and rotary pumps. The open area of strainer is at least
300% (HOLD) of the cross-sectional area of the pipe. The piping is arranged so that the
filter or strainer element can be removed from the flanged joints without altering the
piping, supports or pump alignment.
5.4.32
PIPING AT TURBINES:
Air Inlet and Exhaust duct termination are positioned away from hazardous areas, and
areas frequented by personnel or any open ended or filtered inlet ducts.
Fuel gas piping within the turbine enclosure is subject to strict control with respect to the
number and type of flanged joints, fully welded being preferred. Flanged joints are
provided only for connection to the equipment and for isolation and shut down valves.
5.4.33
PIPING AT DIESEL ENGINES:
All piping connected to diesel engines are arranged in such a manner that adequate
flexibility is maintained so as to effectively isolate the piping from any engine vibration.
Piping is not routed directly over diesel engines.
Fuel lines are not run over exhaust piping or any location where leaks would cause fuel
to impinge on to hot surfaces. Fuel lines incorporate local isolation valves.
The fuel oil header is not dead-ended.
Silencers, where installed in suction and discharge piping, are located as close as possible
to the engine.
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Air intake openings are located away from any hazardous area, face toward the
prevailing wind direction and be in such a position as to limit the ingress of dust (e.g. salt
crystals) and moisture.
5.4.34
PROTECTIVE COATINGS:
Painting, protective coatings and the procedures used for the preparation of surfaces as
per protective coating specification given in the bid document.
Flanges are painted on the flange edges, inside boltholes, and up to the gasket surface.
Piping are insulated where indicated on drawings. The piping to be insulated is grit
blasted and given one coat of primer, only then insulation applied as per relevant BidSpecification.
5.5
MECHANICAL:
Mechanical design broadly covers the following areas:
♦
♦
♦
♦
♦
♦
♦
♦
♦
♦
General design requirements
Material handling
Pumps
Personnel protection equipments
Fire fighting equipments
Process gas compressor
Emergency generator
Gas turbine
HVAC Package
Instrument / Utility air compressor
The detail design requirements are as follows
5.5.1 GENERAL MECHANICAL DESIGN REQUIREMENTS
Unless otherwise stated all equipment shall be designed for location on outdoor area and
must be able to operate in highly saline corrosive atmosphere in condition of high
relative humidity.
All equipment shall be designed to meet the area classification defined in the job
specification.
Maintenance and operational access requirements on all four sides and also over head /
underneath shall be examined while engineering the platform facilities.
All package units shall be furnished as skid mounted equipments totally assembled,
piped, wired and tested on a structural steel base frame. Drip pan with suitably
connected drains shall be provided to avoid spillage of fluids on deck.
Structural design of the base shall allow for:
Æ Static and dynamic equipment loads
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Offshore Design Manual
Æ The design wind load
Æ Seismic loads
Æ Hydrostatic test loads
Æ Lifting, shipping and installation loads.
The quality assurance programme of the vendor (BS EN ISO9001) shall be submitted to
company for approval to ensure that all work is performed in conformity with
specifications & good engineering practices.
The equipment shall be designed and selected for continuous duty unless otherwise
specified.
Fly wheels, sheaves, shafts, coupling and similar hazards shall have removable safety
guards which shall be sufficiently rigid to prevent deflection and shall be constructed
from non sparking material.
Surfaces operating in excess of 60ºC and located within a distance of 2 m above floor shall
be insulated.
Unless otherwise specified the offered equipment or equipment of similar design shall
have been type tested and shall have been in continuous satisfactory service on offshore
for a minimum period of 2 years.
The Design of various Mechanical / Rotary equipments shall conform to the principles
described herein.
5.5.2
MATERIAL HANDLING FACILITIES
Æ Adequate facilities shall be provided on the platform for the following:
ÆHandling and transfer of equipment / sub-assemblies during routine maintenance
Æ Handling and transfer of consumables like chemicals drum etc., between barges and
respective consumption areas shall be in the most convenient matter requiring
minimum time.
Æ Movement of operating personnel through personnel basket
Æ Material handling facilities are broadly categorized as follows:
A. Deck crane
B. Electric operated monorail hoists.
C. Chain pulley blocks.
A.
DECK CRANE
The deck crane is utilized for handling of equipment, materials, drums and
personnel baskets from offshore platform to barges & supply vessels and vice
versa. The capacity of the crane is decided based on the design of the platform in
the concerned project. The equipment shall be designed as per API 2C as
evidenced by the placement of API medallion on the crane.
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The offered equipment model shall have been type tested and shall have been in
continuous satisfactory service on offshore for a minimum period of 2 years. The
crane shall be suitable for operation under the wind and ocean condition for the
given project.
Codes & Standards
The applicable codes & standards are as follows:
Æ API SPEC 2C
Specification for Offshore Cranes.
Æ API RP 9E
Recommended practice on Application, Care & Use of
wire rope for Oil Field Service.
Æ API RP 2D
Recommended practice for Maintenance & Operation of
Offshore Cranes.
Æ NEC
National Electric Code.
Æ IEC
International Electro Technical Commission.
Æ NEMA
National Electrical Manufacturers Association.
Æ ISO 3046
Reciprocating I.C. Engine.
Æ EEMUA 107
Engineering Equipment & Materials User Association.
Æ OSHA
Occupational Safety & Health Act.
Æ AGMA
American Gear Manufacturers Association.
Boom
Boom shall be constructed of structural steel of ASTM A-36 or A 500 Grade B.
Boom shall be of lattice construction and be of sufficient length to reach the areas
of platform which required lifting of equipment / material for maintenance
purposes.
Boom rest shall be so provided so that the boom tip is easily accessible for
maintenance of hoist pulleys.
A cat ladder shall be provided to enable reaching the tip from boom base.
Hoist & Ropes
•
•
•
The crane shall have main hoist, and boom hoist winches driven by
hydraulic motors and fitted with automatic braking system.
Hoist shall employ power load lowering counter balance valve and shall not
lower against brakes.
Each hoist shall be equipped with brake of fail-safe type.
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Offshore Design Manual
•
•
Wire rope for main and auxiliary hoist shall be non twisting type.
Wire ropes shall be suitable for use in marine environment.
Swing
•
•
•
The crane shall be capable of rotating 360º.
Adjustable stop switches shall be provided to enable limiting of crane
rotation, if required.
A lever operated parking brake shall be provided in the cabin, the same shall
be held off hydraulically during swing motion.
Mounting
•
•
The crane shall be mounted on a pedestal support designed and furnished by
the contractor as per requirement of API 2H.
Crane cabin shall be approachable from the deck / intermediate working
platform at all angles of crane position. A swing platform with ladder
approach shall be provided all around the crane pedestal at a height such
that it is 5 Ft below the swing mechanism for ease of maintenance and
approachability of crane from platform in any direction.
Cab
•
•
The cab shall be fully enclosed and equipped with shatter proof glass
windows and shall be mounted in such position so as to provide operator
with full view of boom at all times.
Stainless Steel load charts (one dynamic and other static) based on vendors
ratings shall be placed inside the cabin.
Prime Mover
•
•
•
•
•
•
The primary power shall be supplied by a heavy duty preferably naturally
aspirated industrial type diesel engine for driving the hydraulic pump.
Flame trap in air intake and exhaust to be provided.
There shall be two starting systems Air and Hydraulic.
The hydraulic staring system shall include a manual hydraulic pump in
addition to the engine shaft driven hydraulic pump and accumulator.
The site rating of the engine shall be worked out considering de-rating in
accordance with ISO 3046.
For process platform where utilities are available, multiswivel connection for
power (paging and intercom), fuel and water shall be provided.
Electrical
ƒ All the equipment shall be selected in accordance with the area classification
requirements.
ƒ The lighting system shall include two 400 W swivel type flood lights on the
boom along with a red aircraft warning blinker light on tip of the boom and
another on top of the crane frame.
Controls
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Offshore Design Manual
ƒ
ƒ
ƒ
ƒ
All controls shall operate in a fail safe mode. Brakes shall engage
automatically when any control is placed in the neutral position and also in
the event of engine power failure, loss of hydraulic pressure or control
failure.
Provision shall be made of a hydraulic emergency stop to stop all functions
of the crane without stopping the engine.
Control shall be designed so that one operator can conveniently perform all
maneuvers and speed control.
An automatic safe load indicator shall be provided to give the crane operator
a clear and continuous warning when the load being carried exceeds a
figure not less than 90% of the safe working load of the crane at that radius.
Testing
•
•
•
B.
Operability test of crane at yard and at offshore after completion of
installation.
Rated lifting load operational test with boom at minimum and maximum
working radius. Both main hoist and auxiliary hoist shall be so tested.
All protective equipment and devices shall be tested.
MONORAIL ELECTRIC HOIST
Monorail Electric Hoists are utilized for removal of heavy equipment subassemblies such as rotors for Emergency Generator, Gas turbine, Process Gas
compressor, Main Injection Pumps, etc. for overhaul / maintenance purpose.
The equipment supplied shall include monorail hoist with drive motors, flexible
power supply cable with support rail, Pendant type push button control panel,
limit switches, brakes etc.,
Codes and Standards
Applicable Codes & Standards are as follows:
IS 3938
BS 4465
NEC
NEMA
Monorail Electric Hoist
Electric Hoist
National Electric Code
National Electric Manufacturers Association
Testing
Load test shall be carried out at vendors work, fabrication yard and at offshore.
Load test at 125% of safe working load shall be carried out in presence of the
company / its authorized representative or certifying agency.
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C.
CHAIN PULLEY BLOCK
Chain pulley block are widely used on process / well platforms to meet the
material handling / maintenance requirements.
Codes and Standards
The applicable codes and standards are as follows:
IS 3832
BS 3243
Chain Pulley Block
Chain Pulley Block
For chain pulley blocks operating in hazardous area. The material of rubbing
parts shall be of non-sparking type.
Material for load hook shall be forged brass or aluminum bronze. Load chain
shall be of alloy steel duly galvanized.
Testing
Load test shall be carried out at vendor’s works, fabrication yard and at offshore.
5.5.3
PUMPS
5.5.3.1 CENTRIFUGAL PUMPS :
Centrifugal pumps are the most commonly used equipments on offshore platform and
cover a wide range of applications such as main injection pumps, Booster pumps, Sea
Water Lift pump, Utility water pump, etc. The pumps shall be designed to latest edition
of API 610. The vendor shall have produced at least 2 pumps of comparable type, rating
and design from the proposed manufacturing plant and shall provide evidence of
satisfactory operation of at least 8000 hrs when operating in similar conditions.
Codes & Standards
The applicable codes and standards are as follows:
API 610
Centrifugal pumps for petroleum, heavy duty for the chemical and gas
industry service.
API RP500
Recommended practice for classification of location of Electrical
Installations at Petroleum facilities.
API 670
Non contacting vibration and axial position monitoring system
API 682
Shaft sealing systems
NEC
National Electrical Code
API 671
Special purpose coupling for refinery service
API 614
Lubrication, shaft sealing and control oil systems for special purpose
applications
ASTM
American Society for Testing & Materials
ISO 1940
Balance Quality of Rotating rigid bodies
ISO 518
Hydraulic performance standard
ASME B 16.20 Metallic Gaskets
General
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Offshore Design Manual
• The equipment shall be designed and constructed for a minimum service life of 25
years and for an uninterrupted period of 5 years.
• Balancing of axial thrust shall be achieved by means of individually balanced
impellers, opposed impeller arrangement or the use of balance pistons, however
balance pistons shall not be used for applications involving the pumping of liquids
containing abrasives.
• Net Positive Suction head available shall exceed the Net Positive Section head
required by at least 1 m across the entire operating range, from minimum
continuous flow to 125% of the rated capacity.
• Suction side of all pumps handling hydrocarbons shall be designed for full
discharge pressure unless otherwise specified.
• The flexible coupling shall be designed for the maximum driver power and
maximum speed and torque.
MAIN INJECTION PUMP
• Pumps shall be designed to meet the operating conditions of the water injection
service of the platform with the pumps operating in parallel and any one of the
pumps as a standby pump.
• Pumps shall be HT motor driven and shall normally take suction from Booster
pumps.
• Bearings of the pump shall be hydrodynamic type with force feed oil lubrication.
• Lube oil system shall be common to driver and pump in accordance with API 614.
• Main lube oil pump shall be shaft driven or separate AC motor driven. The
auxiliary lube oil pump shall be of same capacity and shall be AC motor driven.
• An emergency D.C motor driven pump shall also be provided.
• Lube oil shall be cooled with air fin type cooler.
• All shutdown/interlocking, sequential start/stop shall be relay/PLC based and
shall be located in the unit control panel in the central control room.
• Vendor shall provide all the alarms and shutdowns such as high vibration, high
bearing temperature, high motor amperage, low lube oil pressure, etc. required for
safe operation of the pump.
• The key process parameters and machine parameters shall be made available on
the DCS normally envisaged for the process platform
Testing
Æ Performance & NPSH test shall be carried out with parameters recorded at rated flow,
two intermediate points, minimum continuous stable flow and shut off (Performance
only).
Æ Full load mechanical test shall be carried out for the complete module including all
contract equipment for at least 4 hours.
Æ Sound level test.
Æ A continuous 72-hour run test at site shall be conducted for each pump.
BOOSTER PUMP
Æ Booster pump shall supply water to main injection pump to provide adequate NPSH
required by MIP’s.
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Æ Pumps shall be designed to meet the operating conditions as specified on the bid
package with pumps operating in parallel.
Æ The pump casing shall be axially split design for ease of maintenance.
Æ Pump shall be fitted with mechanical seals.
Æ Vendor shall provide High Vibration (Motor & Pump), High bearing temperature and
High motor winding temperature alarms and shutdowns for safe operation of the unit.
Æ Various operating parameters including alarms and shutdown shall be available at the
DCS normally envisaged for the process platform
Testing
♦
♦
♦
Each pump shall be tested for performance & NPSH test with parameters recorded at
rated flow, minimum continuous stable flow. Two intermediate points, shutoff head.
Full load Mechanical run test of the complete package shall be conducted using all
contract equipment, auxiliaries and controls at rated flow for a minimum period of
four hours.
Sound level test shall be carried out
SEA WATER LIFT PUMP
Æ Seawater lift pumps shall be motor driven vertical shaft type pumps for pumping raw
seawater into de-oxygenation towers through filter.
Æ Pumps shall be designed to operate in parallel with any pump being kept as standby,
standby pump shall start automatically when any of the operating pump fails.
Æ Non-reverse ratchet shall be provided to prevent reverse rotation of pump.
Æ Line shaft bearing shall be self-lubricating type, bearing material shall be suitable for
dry running during startup.
Æ Pump assembly shall be such that it can be lifted/dismantled for repair/maintenance
in the space available over mounting floor.
Æ Vendor shall provide alarm and shutdown signals for High vibration (Motor &
pump), High temperature (Motor bearing & Motor winding) and high motor
amperage.
Testing
Æ Each pump shall be tested for performance at rated speed preferably with full column
length assembly.
Æ Mechanical run test of the entire package shall be carried out with all contracted
equipments
FIRE WATER PUMP
Firewater pump installed on Offshore Platforms are Diesel Engine Driven vertical shaft
type. The packager shall have engineered, manufactured, packaged, installed &
commissioned at least two packages of similar or higher sizes for fire water services for
offshore platforms and same shall have been operated successfully/satisfactory for a
period of at least 3 years with out any major overhaul. The offered pump and diesel
engine model shall be one from existing regular production range of the vendor.
The major codes & standards applicable are as follows:
NFPA 20
National Fire Protection Association.
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Offshore Design Manual
API 610
ISO 3046
EEMUA
NEC
NEMA
API RP 14C
AGMA
Centrifugal Pump for General Refinery Service
Reciprocating Internal Combustion Engine.
Engineering Equipment & Material Users Association (Publication
No. 107)
National Electrical Code
National Electrical Manufacturers Association.
Analysis, Design, Installation and Testing of Basic Surface Safety
Systems on Offshore Platform.
American Gear Manufacturers Association.
Complete package shall be designed and manufactured for continuous duty operation
even though operation of the pump is intermittent.
Pump
♦
♦
♦
♦
♦
Pump assembly shall be such that it can be lifted and dismantled for
repair/maintenance in the space available over the mounting floor.
Pump column shall be furnished in flanged section.
Pump shall be installed in a caisson pipe.
Thrust bearing shall be provided in the gearbox to withstand thrust load caused by
the pump.
Line shaft bearing shall be self lubricated type and shall be suitable for dry running
during pump startup.
Right Angle Gear Box
♦
♦
Gear Box shall be furnished with heavy-duty thrust bearing.
Non-reverse racket arrangement shall be provided in gearbox to prevent reverse
rotation of pump.
Engine
♦
♦
♦
♦
Diesel Engine Driver shall be in accordance with NFPA 20 & ISO 3046
The engine site rating should be at least 10% higher than the maximum power
required by the pump.
The capacity of engine fuel tank should be sufficient for 24 hours continuous
operation at full load.
Engine shall have two starting systems air and hydraulic starting.
Controls
♦
♦
Pump control system shall be designed for single push button start of the auxiliaries,
driver and pump in proper sequence from a locally mounted push button station,
remote control panel and console of DCS.
Control system shall also include automatic starting by any of the following
situations:
o
o
Activation of low-pressure switch in the firewater header.
Melting of fusible plug in the pneumatic loop or activation of manual FSD
Station served by pressure switch mounted on vendors local control panel.
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o
o
o
On receipt of signal from Fire and Gas Detection System, if the primary fire
water pump fails to start after six cranking of the diesel engine or the
primary pump is under maintenance an automatic signal shall start the first
standby fire water pump if available on a bridge connected platform.
Vendor shall furnish an Automatic type controller as per NFPA 20.
The Local Control Panel shall conform to NEMA 4 & 7.
Testing
♦
♦
♦
The performance test and mechanical running test for pump, gear and engine shall
be carried out as per the respective codes.
Sound level test at equipment manufacturers shop shall be carried out for each
equipment to verify the estimated noise level. Sound level test of the package shall be
carried out during package test.
A package test shall be conducted using the contract equipment, auxiliaries and
control for a minimum of 4 hours.
5.5.3.2 ROTARY GEAR PUMP
Rotary Gear Pumps are used for varied application on Offshore Platforms. Rotary Gear
Pumps are used as diesel transfer pump, chemical transfer pump for oil corrosion
inhibitor, gas corrosion inhibitor, demulsifier, pour point depressant and for any other
similar use in accordance with data sheets.
Codes and Standards
API 676
NEC
NEMA
IEC
Positive Displacement Pump – Rotary
National Electric Code
National Electrical Manufacturer’s Association
International Electro Technical Commission
Design Requirements
♦
♦
♦
Pump shall be designed, manufactured and tested in accordance with API 676. (latest
edition)
Integral Pressure relief valve shall be provided with each pump.
Vendor to provide pulsation dampeners, if required.
Test Requirement
Besides the test mentioned in API 676 following tests are carried out:
♦ Relief Valve Set Test
♦ Performance Test
5.5.3.3 CONTROLLED VOLUME RECIPROCATING PUMP
The pumps covered under this specification shall be used to inject chemical corrosion
inhibitors in well heads to outgoing flow line.
Codes and Standards
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The following codes (latest edition) are made part of pump specification.
API 675
NEMA
NEC
IEC
Positive Displacement Pumps – Controlled Volume
National Electric Manufacturer’s Association
National Electric Code
International Electro Technical Commission.
Design Requirements
Pump is to be designed, manufactured and tested as per latest edition API 675 and to suit
saliferous environment.
All electrical equipment selected for hazardous area shall be certified by BASEEFA, UL
or equivalent international testing agency.
The pump shall be lightweight, compact and containing minimum number of working
parts for maintenance.
In case of gas driven pump the exhaust gas from pump driver shall be collected and
taken to common header.
All parts of the pump/pump driver coming in contact with utility gas shall meet the
requirements of NACE as per MR-01-75. Also all valves, piping, fitting and instrument
on the utility gas line shall meet NACE MR-01-75.
Pulsation Dampener shall be designed as per ASME Section VIII Part VI.
Pump to be provided with manual capacity control.
Test Requirement
In addition to all tests as under API 675 the following tests have to be carried out.
Æ Flow repeatability and linearity test
Æ Noise and vibration
Æ Relief Valve Test
PERSONNEL PROTECTIVE EQUIPMENT
As the safety hazard cannot be fully eliminated controlled or isolated by engineering
means in the offshore environment, the use of personal protective equipments is enforced
through various equipments described below ; all life saving equipment need approval
by Statutory Authority & a certificate has to be submitted to company for approval.
Codes and Standard
Following codes and standards (latest edition) are followed for all life saving
equipments.
ƒ Specifications to the international convention on safety of life at sea (SOLAS) and its
amendments.
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ƒ USCG-CG-320 “ Rules and Regulations for Artificial Island and fixed structure on the
outer continental shelf.
SURVIVAL CRAFT
Survival Craft forms an essential part of the safety equipment on Offshore Process
Platform and provides a safe means of personnel evacuation from platform in case of
emergency. The survival craft shall be of totally enclosed type.
Codes and Standards
The applicable codes and standards are as follows:
SOLAS
NEC
NEMA
International Convention of Safety of Life at Sea
National Electrical Code
National Electrical Manufacturers Association
Equipment Design
Æ Survival Craft shall be constructed from fire retardant fiber glass reinforced plastic.
Æ Craft shall be sea worthy for 100 years storms condition.
Æ The survival craft shall be powered by suitably sized diesel engine of marine duty.
Æ Diesel engine shall be provided with:
Æ Hydraulic powered starting system with manual pump override
Æ Manual starting with hand cracking
Æ Complete radio system shall be supplied.
Æ Launch platform shall consist of cantilever type structure to hold and support the
craft.
Æ The winch shall be electric motor driven. The system shall be so designed to control
the descent without the aid of electric power.
Æ The equipment furnished shall have approval of statutory authority.
Æ Vendor shall give an on site demonstration of the craft including launching and
recovery operation correspondence to full capacity.
Æ Survival craft shall have approval of a Statutory Authority.
INFLATABLE LIFE RAFTS
Æ Each life raft shall be self-inflatable type installed in self launching mode
(inclined at 45º).
Æ It shall confirm to SOLAS specification Chapter III.
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Æ Material used for life raft shall be suitable for saline and corrosive atmosphere.
Æ At least one life raft is provided on each cellar and main deck.
Æ Inflatable Life Raft should not inflate in air.
Æ Inflatable life raft shall have approval of Statutory Authority.
LIFE PRESERVERS (LIFE JACKET) AND MARINE WORK VEST
Æ Life preserver shall provide 16 kgs (38 pounds) buoyancy in fresh water for 24 hours.
The buoyancy shall not be decreased by more than 5% after 24 hours of submergence in fresh water. It shall be bright orange in colour.
Æ Each life jacket shall comply with regulation of Chapter III of SOLAS.
Æ Marine work vest shall comply with regulations of chapter IV of SOLAS – Marking
and labeling shall be screen-printed in water resistant, vinyl ink.
Æ Life preserves and marine work vest shall be approved by Statutory Authority.
LIFE RING BUOYS
Æ Life Buoy shall be capable of floating in fresh water for 24 hours, with a weight of 16
kg iron suspended from it.
Æ It should be capable of withstanding a drop test into water from a height of at least 38
metres.
Æ Life buoy shall have self igniting light.
Æ Life ring buoy shall also meet the requirement of SOLAS regulation , Chapter III.
Æ Life Buoy shall have approval of Statutory Authority.
FIRST AID KIT
The contents of kit shall include the following item as minimum.
a)
b)
c)
d)
e)
f)
g)
h)
i)
j)
Triangular Bandages 90 cm (wide) x 127 cm (base)
First Aid Dressing
Burn Dressing
Roller Bandages
Water Proof Adhesive Tape
Pre-medicated Adhesive Dressing Strips
Cotton Wool (Sterilized)
Ophthalmic Pads
Antiseptic & Burn Ointment
Mouth to Mouth Resuscitation consisting of a short oral
airway with NRV
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08 nos.
06 nos.
03 Nos.
04 Nos.
01 Roll
10 nos.
03 nos.
2 nos.
1
1 nos.
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Offshore Design Manual
The container shall be weatherproof box.
Personnel Basket and Scramble Net
Æ Each personnel basket shall be suitable for a minimum of six (6) men.
Æ Scramble net shall support a minimum of twenty four (24) men simultaneously.
Miscellaneous Items
Æ Eye goggles – cup type, rubber framed
Æ Self contained open circuit compressed portable air breathing pack.
Æ H2S & Safety Information Chart
Æ Portable eye wash bottles.
5.5.5
FIRE FIGHTING EQUIPMENT
DCP SKID
Dry chemical fire extinguishing system is means of applying dry chemical powder that
can be automatically or manually activated to discharge through a distribution system
onto the protected hazard. Dry chemical powder is composed of very small particles
usually sodium bicarbonate, potassium bicarbonate based with added particulate
material suspended by special treatment to provide resistance to packing, resistance to
moisture absorption (baking) and proper flow capabilities.
Codes and Standards
NFPA
National Fire Protection Association. Standard No. 17 – Dry Chemical
Extinguishing System.
Boiler and Pressure Vessel Code. Section-VIII, Div. I
ASME
The offered DCP skid or DCP skid of similar design manufactured by the same supplier
shall have been type tested and UL listed and shall have been in continuous satisfactory
service on offshore for a minimum period of 2 years.
General
The type of hazard and equipment that can be protected using dry chemical
extinguishing system consists of flammable liquid/gases/solids and electrical hazards.
Dry Chemical Skid consists of following minimum equipment:
Æ Nitrogen system
Æ Chemical Storage vessel
Æ Actuator system
Æ Hose Reel assembly
Design Requirement
Æ A dual actuation (Manual/pneumatic) control system is provided for the DCP skid.
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Æ DCP system to have capability of nitrogen cylinders and cartridges being replenished
on the platform from indigenous source.
Æ The amount of dry chemical in the system shall be at least sufficient for the largest
size Hazard protected, or for the group of hazard that are to be protected
simultaneously.
Æ The capacity of nitrogen cylinder is such that its adequate for the full time of discharge
of powder at required pressure.
Æ The hose shall be non-collapsible type with all weather neoprene covering,
conforming to NFPA requirements. Hose to be UL listed for their intended use.
Æ Corrosion allowance for the dry chemical container shall be minimum 3 mm.
Æ The nozzle shall be push lever type with pull pin designed for dry chemical service.
The nozzle should have an effective range of not less than 8 meters.
Æ Number of DCP skid on process platform is finalized during detailed engineering
based on equipment layout and safety norms. On well platform a DCP skid is placed
on each cellar deck, main deck and helideck.
Tests
Æ Operational test of each skid is conducted at fabrication yard and at offshore.
FIRE BLANKET AND FIREMAN’S OUTFIT, STRETCHER
Æ Fire blanket shall be processed with fire proofing chemical. Complete set of fireman’s
outfit shall be furnished in accordance with SOLAS.
Æ Stretcher shall be rigid, in which injured person can be securely and comfortably
strapped and hoisted. It shall be of bright orange type.
Æ Fire blanket and Fireman’s outfit and stretcher shall have approval of Statutory
Authority.
Helicopter Rescue Kit
Helicopter rescue kit shall contain:
a)
b)
c)
d)
e)
f)
g)
h)
Crow bar
Fire Axes
Bolt Cutter
Fire Blanket
Hand Safety Lamp
Protective Clothing
Hack saw
Rescue Knives
-
2
2
1
2
2
2 sets
2
2
PORTABLE FIRE EXTINGUISHERS
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•
All fire fighting
codes/standards.
NFPA
API RP 14G
API RP 2G
ISI
♦
♦
♦
♦
♦
equipment
shall
be
designed
according
to
following
National Fire Protection Agency
Recommended Practice for fire prevention and control on
offshore production platform.
Recommended practice for production facilities on offshore
structures.
Indian Standards Institution standards
All extinguisher have to be ISI stamped.
Extinguisher shall be suitable for Class B,C & E fire as per IS:2190.
Dry Chemical shall be potassium bicarbonate based with properties confirming
to IS:4308.
CO2 extinguisher shall be as per IS 2878
Fire extinguisher used on offshore platform are generally:
Æ 10 kg dry chemical extinguisher
Æ 4.5 kg CO2 extinguisher
Æ 3 kg CO2 extinguisher
•
All extinguishers shall be portable type with a carrying handle and wall hook or bracket for
mounting when not in use. Each extinguisher to be installed in weather proof box.
PROCESS GAS COMPRESSOR
The centrifugal compressor is used to compress associated gas or free gas produced in
offshore platform for transmission to onshore terminals. The compressor design is based
on API-617 and the codes referred therein. The basic input data relating to the design of a
compressor are obtained from the project conceptual report.
Codes & Standards
The major codes & standards associated with Process Gas Compressor are as follows:
API 617
Centrifugal Compressors for General Refinery Service.
API 616
Combustion Gas Turbine for refinery service.
API 614
Lubrication, Shaft Sealing & Control Oil System for special
purpose application.
API 670
Vibration & Axial position & Bearing Temperature Monitoring
Systems.
API 671
Special purpose coupling for refinery service.
API 661
Air cooled heat exchangers for refinery service.
API 613
Special purpose gear unit for refinery service.
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API RP 14C
Analysis, Installation & Testing of surface safety systems on
offshore production platform.
API 676
Positive displacement pump rotary.
ASME PTC 10
Test code for compressors and exhausters.
ASME SEC VIII
DIV. 1
ANSI
Pressure vessel code.
ISO 1940
Balance Quality of Rotating rigid bodies
American National Standard Institute.
Compressor & Module Design:
•
•
P&ID furnished in the bid are the preliminary estimates based on ideal gas. This is
indicative of the compressor module vendor’s scope at the battery limits.
Based on the above parameters the compressor manufacturer shall carry out the process
design based on real gas, preferably using the BWRs relations.
•
Performance Guarantee shall be provided at the rated conditions as provided in the
specification.
•
Vendor data requirements, including performance curves for different sections and also
composite curves, shall be as per the API 617 code.
Vendor is required to furnish a single lift compressor module capable of fitting in the
space allocated for module in tentative layout drawing of the platform.
Safety requirement for module design are as per API-RP-14C, 14G and 14F and OSHA.
Structural analysis shall be as per API 617 and codes referred therein shall be complied.
Fire detection system based on UV and thermal detectors and a fire suppression facility
consisting of CO2, water sprinklers and clean agent system (control room) shall be
provided.
Sealing System
Compressor sealing system may be gas seals or liquid seals as specified in the bid
specifications.
Seal oil system shall be designed as per API 614.
For oil shaft seal provision shall be made for an overhead tank having sufficient capacity
to last for total period of run down and isolation of compressor train.
Seal oil chosen shall have a life of over 12 months.
Knock out Drum (KOD)
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The KOD shall be ASME coded vessel. The sizing follows from the inter stage pressures
and volumes arrived from the process design by the vendor.
Coolers
•
•
•
•
Design shall be based on 14 deg. C approach to maximum ambient site temperature
specified in the project specifications
The mechanical design shall be based upon ASME code.
Air cooled design shall be employed unless specified otherwise.
The material of cooler shall be selected to provide for a cooler life of 25 years.
Piping
All gas piping shall be of 316L. The vendor shall ensure low pressure drops by adequate
sizing as per good engineering practice.
Instrumentation System
The control system is designed for automatic remote control start up and shut down.
The compressor train shall be provided with suitable antisurge protection and load
sharing system (if required)
Gas Turbine Driver
•
•
Gas turbine driver shall be simple cycle , preferably heavy duty industrial type,
having adequate track record in offshore experience as specified in the bid package.
The site rating shall be base continuous with 105% margin over the power required at
site ambient temperature specified for the project.
Fuel System
Gas turbine shall be equipped with dedicated fuel gas treatment system capable of
handling saturated gas as a measure of protection against failure of gas turbines.
The complete fuel conditioning system construction shall be of SS316L.
Inlet Air system
The air filtration system
washable/disposable type.
shall
be
3
stage
marine
type
having
filters
of
The minimum design life of filter elements shall be 6 months for the condition prevailing
at site. The construction of inlet system shall be of stainless steel.
Lube oil system
A combined lube oil system based on API 614 for compressor, turbine and gearbox (if
any) shall be provided.
Exhaust System
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The exhaust stack shall be preferably straight up type . the material shall be selected to
ensure the design life of the platform.
Testing Requirements
For the major components the following are the tests:
Æ Performance Test of Compressor as per ASME PTC 10
Æ Mechanical Run Test of Compressor as per API 617
Æ Performance and Mechanical Test of Gas Turbine based on ASME PTC22 and
API 616 respectively.
Æ Gear unit test for load
Full Module Tests:
Æ Full Load Full Speed String Test of the module
This test shall be conducted for 4 hours. This test is conducted with all auxiliary
contract equipment.
Æ 72 hour site commissioning test
This is the final test before handing over the unit in the platform and is a non stop 72
hour test to establish the equipment performance in actual conditions
EMERGENCY GENERATOR
Emergency Generator is a diesel engine driven generator used for emergency power
generation and supplies power to motors, communication equipments, lighting and
utility loads on the platform during periods when the main generating sets are
shutdown and during platform start-up. It takes emergency and critical load of platform
and is also used in Black Start of platform.
Codes and Standards
ISO 3046/ BS-5514
ANSI
ASTM
NEC
NEMA
IEEE
IEC
EEMUA
API RP 14C
Reciprocating IC engines
American National Standard Institute
American Society of Testing of Materials
National Electric Code
National Electrical Manufacturer’s Association
Institute of Electrical and Electronic Engineer’s
International Electro-technical Commission
Engineering, Equipment and Material User’s Association
(Publication No. 107) “Recommendation for the protection of
diesel engines operating in hazardous area”.
Analysis, design, installation and testing of basic surface, safety
system in offshore production platform.
Prime Mover
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Prime mover is diesel fuel operated, water cooled, naturally aspirated or turbo charged
engine.
Diesel engine is designed for continuous duty indoor location on an offshore platform.
The offered diesel engine shall be one of regular production models of the manufacture
for offshore industrial application and already type tested. In case the proposed engine
model has not been type tested, vendor to furnish a reference list of its existing
installation and atleast two of these engines should have completed 8000 hrs (each) of
continuous running on offshore installation.
The engine is rated to continuously develop net electrical power equal to the specified
generator continuous rating (in addition to the electrical power requirement for
emergency generator auxiliaries) under the worst site condition as indicated in generator
data sheet. The engine shall also be capable of providing an overload power of 110% of
the continuous rating at the same crank shaft speed for one-hour with or without
interruption, within a period of 12 hours of operation.
De-rating of engine to be done in accordance with ISO-3046 / BS-5514.
The engine shall have positive displacement, gear type lubrication oil pump for
supplying oil under pressure.
The engine shall be equipped with an air motor starting system. Diesel engine driven
compressor along with suitably sized air receiver for black start condition. Additionally,
the engine has hydraulic start system with provision of priming by engine or hand.
Generator
Generator rating indicated in the data sheet shall be the net output of the set after
accounting for all auxiliaries for the prime mover and generator. Generator voltage to be
415 v.
Generator shall be suitable for operating in parallel with normal power supply of the
platform.
Generator to operate satisfactorily under sudden load rejection and sudden load
application. In case or sudden application of full load at rated power factor, the voltage
drop shall not exceed 15% of the rated voltage. The rated voltage shall be restored within
0.5 to 0.8 secs.
The voltage regulation of the machine shall be within ±2% of the nominal voltage. The
generator shall be suitable for continuous operation at rated load for a frequency
variation of ±3% of rated value.
The generator shall be capable of withstanding 10% overload for one hour and 50%
overload for one minute.
The control of emergency generator shall operate in fail safe mode. The generator set
shall function as per one of the following scheme:Æ Auto main failure scheme (AMF)
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Æ Manual start in service mode
Æ Manual test mode
Testing of Emergency Generator
Æ String Test
String test is carried out on complete diesel engine generator as per electrical
specification.
Æ Site Test
The complete emergency generator set shall be tested at site in accordance with IEC46.
Æ Shop Test
Engine to be tested separately at engines manufacturer’s shop as per diesel engine
data sheet and ISO 3046.
The engine generator set shall be run at synchronous speed non-stop for two(2)
hours, at it rated capacity.
GAS TURBINE
The Combustion Turbine employed in Offshore projects is a simple gas cycle machine to
be designed in accordance with API 616 (latest edition). The turbine may be Industrial
or Aero-derivative type. Turbine Driver for Mechanical drive requirements e.g. Process
gas compressor are two shaft machines whereas turbine for Power generation
requirements may be single or two shaft designs. The turbine shall be capable of
supplying the power requirement with the specified power margin on a continuous duty
basis based on the stated site and environmental conditions specified in the bid package.
The power ratings shall include all site and operating allowances such as inlet and
exhaust losses (including losses discharging through the Waste Heat Recovery Unit if
specified for the project).
As the process facilities are designed for a life of 25 years the gas turbine shall be
designed and constructed for a period of 25 years. The gas turbine and auxiliary
equipment shall be suitable for at least three years of uninterrupted continuous full load
duty.
Codes and Standards
Some of the major codes and standards associated with the Gas Turbine are as follows:
API 616
API 614
API 613
API 671
API 670
API 661
Gas Turbine for refinery service
Lubrication, Shaft sealing and control oil systems for special
Purpose applications
Special purpose gear units for refinery services
Special purpose coupling for refinery services
Vibration and Axial position and Bearing Temperature
Air cooled Head exchangers for General Refinery Services
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ASME PTC22
ASME B31.3
API RP500
ISO 1940
Performance Test Code for Turbine
Codes for Chemical Plant & Petroleum Refinery Piping
Classification of areas for Electrical Installations
Balance Quality of Rotating rigid bodies
The other project specifications for Instrumentation, Piping fabrication & Installation,
Insulation, Pressure Vessel, Specification for welding, etc. are made a part of specification
for Gas Turbine.
Gas Turbine Selection
The Gas Turbine catalogue ratings are at ISO conditions which are :
Ambient Temperature
Attitude
Relative Humidity
Ambient pressure
Driver Catalogue rating =
conditions
-
15 deg.C
0’
60%
101.3 kpa
Driver Site rating + Power loss due to environmental
Driver Site rating = Driven equipment power requirement + Drive loss in gearbox &
coupling + Power margin
While making power calculations various losses are considered on following account:
Gearbox loss – around 2%
Electrical Generator loss – around 2%
Inlet and exhaust loss – around 1%
Loss on account of humidity as per standard curve
Loss on account of elevation as per standard curve
Loss on account of suction air temperature as per standard curve
Based on the power calculations with losses on above basis, the gas turbines with
proven offshore track record may be selected. As per existing criteria turbine models
having completed satisfactorily at least 8000 hrs. of continuous operation on the offshore
installation under similar operating conditions are considered.
The following
Performance guarantee are taken from the vendor with no negative tolerance:
Æ Gas Turbine site rated power output (MW)
Æ Gas Turbine heat rate at rated output (KJ/KW-hr)
Gas Turbine enclosure
The Gas turbine shall be enclosed in a weather proof and noise attenuating housing. The
auxiliary system like lube oil system requiring routine maintenance shall be housed
outside the enclosure.
Enclosure ventilation shall be provided with electric driven fans with 100% standby
capacity.
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For power generation application the enclosure shall be maintained at a pressure of at
least 5mm of water less than atmospheric and for Process gas Compressor at a positive
pressure of at least 5mm of water by operation of only one ventilation fan.
An interlock shall be provided such that in the event any enclosure door of the turbine is
not properly closed/gets opened due to any reason the turbine should automatically
shutdown/its start blocked.
Fire and Gas Detection
The enclosure shall be designed with gas (Hydrocarbon & H2S) detection, fire detection
and fire suppression system.
The detectors shall provide a two step alarm (20% and 60% LEL, 10ppm & 50ppm of
H2S) of rising concentration of gases before the hazard level (100% LEL/100ppm H2S) is
reached.
The coincident detection of the 60% LEL of gas or 50ppm H2S shall ensure shutdown
with cut off of fuel gas supply.
The manifestation of fire is sensed by either Ultraviolet light detectors or Fixed
temperature thermal detectors.
Fire extinguishing in the enclosure is by CO2 or clean agent fire extinguishing type.
Fire suppression system shall be so designed that it can be activated automatically by
receiving a signal from coincidental UV detection or thermal detection or can also be
manually activated by an operator.
Lubrication system
The lubrications system of turbine and it’s driven system shall confirm to API-614.
Lube oil may be cooled with air fin fan type of coolers with standby fan sized for 100%
capacity. The main and standby lube oil pumps shall be powered by AC motor if main
lube oil pump is not shaft driven as per vendors standard.
An emergency pump powered by a DC motor to provide lube oil for coast down and
cooling period. A common portable lube oil purifier and a trolley mounted lube oil
pump for filling/draining out from reservoir are also included in turbine system.
Coupling and Gear Box
The couplings shall be flexible non lubricated type as per API 671 with a non sparking
guard.
The gearbox if required between the gas turbine and driven equipment shall conform to
API 613. Performance test shall also be conducted on gearbox at full speed and full load
in accordance with API 613.
Fuel Gas System
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The fuel gas treatment system for the gas turbines shall be designed for ISO rating of the
gas turbine or shall meet the turbine starting acceleration requirements whichever is
higher.
It shall consist of twin knockout pots for removal of condensate with level indication and
auto drain taps, fuel strainers/filters with differential pressure indicator and alarm and
fuel gas super heater.
All liquid/gas fuel piping and valves shall be in 316L stainless steel or higher grade as
required.
Air intake and exhaust system
The intake air system including ducting, intake filter frames, plenum and hardware shall
be manufactured from SS316L material suitable for withstanding the corrosive marine
environment.
The filter system shall be designed to meet the mandatory filteration standards
prescribed by the turbine manufacturer but as a minimum shall meet the following
requirement:
Æ Removal of 99% particles greater than 5 micron
Æ Removal of sodium or potassium chloride concentrations greater than 0.01ppm
Æ Average synthetic dust weight arrestor as per BS6540.
The air filter shall be 3-stage marine type described as under:
1st stage:
Washable type Pre filter for maximum solids/salt removal and water
coalescence. It should be possible to remove the 1st stage filter cartridge
during turbine operation for maintenance.
2nd stage:
High efficiency type filter to remove smaller particles passing through 1st
stage.
3rd stage:
Inertial vane separator bank to remove water particles retained in the air
flow.
•
•
•
Filter elements shall be washable type and minimum expected life shall be 5 years.
The Air intake filter shall be oriented in such a way that no exhausts/vents are re
circulated in the gas turbine intake system.
The exhaust system shall be so designed so as to preclude the possibility of
heating of other equipments, causing hinderance in Helicopter flight paths and
crane operations.
HC gas detectors shall be provided inside the air intake system.
General Mechanical Requirements
a.
Noise level of any point of package including ducts shall be such as to restrict the noise
level to within 88 dBA at any point located 1m away from surface.
Surface temperature of any exposed part likely to come in contact with humans shall not
exceed 60 deg.C.
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Vendor shall include a crank detergent/water wash cleaning system including one set of
common portable washing equipment.
Access to the turbine and associated auxiliary equipment on the skids for operation and
maintenance is of utmost importance. The contractor shall include all lifting points,
monorail electric hoists, overhead cranes, etc. necessary for handling maintenance lifts till
the designated material handling area on the deck.
Controls
All the turbine controls shall operate in a fail safe mode.
The control system shall be designed for local and remote startup and shutdown.
The control system shall be distributed microprocessor based consisting of redundant
microcomputer section with video display and membrane keyboard for operator
interface. The system shall be provided with sufficient level of redundancy such as
processor and power supply so that a single failure would not cause total shutdown.
The system shall have self diagnostic feature to card/module level so that in case of
failure of the concerned card/module can be removed, repaired and returned to service
without interrupting operation of unit.
The system shall have non volatile memory or shall have battery backup.
A programming unit shall be provided for the system to enter/alter program.
The critical parameters of the machine shall be duplicated in the DCS ( Distributed
Digital Control System normally envisaged for the process platform ) operators
monitoring, event/alarm logging, trending and periodic logging through serial digital
communication interface.
The local control panel and local gauge panel shall be mounted locally on the skid
whereas the UCP shall be in the CCR.
Startup and shutdown
The turbine drivers shall be equipped with AC motor driven starting system.
The system shall be designed to provide reliable programmed starting, acceleration and
full load operation of the unit along with shutdown of the system .
Vendor shall provide suitable alarms and shutdowns such as over speed, high
temperature, high vibration etc for safe operation of the unit.
Testing
The turbine shall be subjected to a mechanical running and performance test (ASME PTC
22) to confirm its performance, power generation, fuel consumption, vibration levels etc.
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A mechanical string test (full load, full speed) for not less than four continuous hours
shall be carried out with all contractor supplied driven equipment including gearbox,
lube oil system, control system, etc. specific to the project.
The test shall include but may not be limited to verifying the performance of such system
as :
Æ Run down without AC power
Æ Package control & instrumentation system
Æ Package safety systems such as shutdowns, alarms, sensors and monitors.
Noise test shall also be carried out on the gas turbine during testing.
Tools and spare parts
The contractor shall provide a recommended spare part list to cover the commissioning
and one year operations. The contractor shall provide special tools for the erection,
operation and maintenance of the gas turbines including boroscopic tools with camera.
HVAC PACKAGE
The HVAC system shall be used to maintain desired environmental conditions inside the
living quarter module, switchgear module, TG control room, etc. on the offshore process
platform. The system shall comprise of two components namely:
A.
Chilled water type centralized air conditioning system comprising broadly:
♦
♦
♦
♦
♦
♦
B.
Compressors with drivers
Condensers
Chillers
Air Handling Units (AHU’s)
Chilled Water Pump
Network of Refrigerant Piping, ductwork and controls.
Ventilation system comprising:
♦
♦
♦
♦
Supply air fans with drivers
Exhaust fans
Duct work with dampers
Associated instruments & controls.
The offered equipments or equipment of similar design manufactured by the same
supplier shall have been type tested and shall have been in continuous satisfactory
service on offshore for a period of 2 years.
Codes & Standards
The major codes and standards to which the equipment shall comply are as follows:
ASHRAE
American Society of Heating, Refrigeration & Air Conditioning
Engineers
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NEMA
NEC
SMACNA
AMCA
ARI
NFPA
ASTM
National Electric manufacturers Association.
National Electric Code.
Sheet Metal & Air Conditioning Contractors.
Air Moving & Conditioning Association.
American Refrigeration Institute.
National fire Protection Association.
American Society for Testing and Materials.
Air Conditioning System
♦
♦
♦
A centralized air conditioning plant working on chilled water system or Direct
Expansion (DX) shall be provided.
Outside air for air conditioning, ventilation and pressurization shall be taken from a
safe area as classified in the area classification drawing. The exhaust of ventilated
areas shall be let into safe area.
Areas to be air conditioned shall include as a minimum the following:
¾
¾
¾
¾
¾
¾
¾
¾
¾
♦
Areas to be spot cooled are as follows:
o
o
o
♦
Kitchen / Tea Room
Laundry & Wash Room
Toilets & Shower Room
Areas to be ventilated shall include:
o
o
o
♦
♦
Living quarter accommodation (except those requiring spot cooling)
Switchgear Room
Control Room
RTU Room
Recreation room
Lounge/Library
Conference Room
Radio Room
All workshops including Machine shop, Electronic/Electrical shops, stores
Battery Room
Emergency Generator Room
Transformer Room
No return air is to be taken from laboratories, dining hall and infirmary.
All areas which are air conditioned shall provide guaranteed inside conditions as
specified in the project conditions and all equipment shall be suitable for meeting the
worst outside ambient conditions as specified for the project.
Chilled Water Package
• Chiller package shall comprise of compressors, driver, chiller, air cooled condenser,
associated hookup piping and fittings.
• There shall be 100% standby for chilled water packages.
• Separate chilled water pump set shall be provided with each chiller package
(working or standby).
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• The system shall provide adequate interchangeability so as to operate any chiller
package with any chiller pump of the system under consideration.
• Refrigent utilized for chilled water package shall be environment friendly (non zone
depleting).
Air Handling Unit (AHU)
• Air handling unit shall comprise air filters, dampers, chilled water coils, electric
heaters, centrifugal fans etc.
• Each AHU shall be equipped with two nos of centrifugal blowers each of 100%
capacity.
• In the event of failure of air conditioning system the blowers would continue to run
to maintain the specified positive pressure.
Pressurization
• Positive pressurization of around 5mm of water gauge shall be maintained at all
times in the areas specified in the project.
• A purge cycle shall occur upon startup and upon a loss of pressurization.
• Humidity and temperature control are not necessarily maintained during purge
cycle.
• Non-explosion proof electrical equipments shall be energized only after the purge
cycle is complete.
Ventilation
• The areas shall be ventilated at the rate of 12 air changes/hour or based on maximum
room temperature rise of 5ºC whichever gives higher air change/hr.
• For emergency generator actual dissipated heat rejection of generator at full load to
be considered for ventilation requirement of emergency generator room.
• Ventilation for battery room and emergency generator shall be by means of forced
filtered air supply and forced air exhaust system.
Control System
•
•
•
The control system should incorporate basic controls in the control panel to maintain
constant room temperature, humidity and positive pressure as specified in the
project specifications.
Room conditions shall be controlled with the help of room mounted thermostats and
humidistat.
Control circuit and interlocking shall be provided so that compressor shall not start
unless:
o
o
o
The AHU fan motors are switched on
The condenser fan motors are switched on
The chilled water pump motors are started
Testing
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•
•
•
All the equipment shall be performance tested at the manufacturers works as per the
relevant code and standards. The chilled water piping shall be checked for proper
insulation and leakage.
Dry & wet bulb temperature of the various constituents of the system shall be
checked.
The building pressurization (5 mm of water column ) shall be checked.
I/U AIR COMPRESSOR
The instrument & utility air requirement of the process platform are met through the
Instrument & Utility Air Compressor cum Air Drier Package. The compressor can be
reciprocating type complying with API 618 or screw type designed in accordance with
API 619. The system broadly comprises of Electric Motor Driven Compressors, Air Inlet
Filter & Silencers, Moister Separators, Intercoolers & After Coolers, Twin Tower Heatless
type absorption air driers, Control System etc.
Codes & Standards
API 618
API 619
API RP 500
API 661
ASME SEC. VIII
ASME 31.3
NEMA
ASTM
NEC
Reciprocating Compressors for General Refinery Service.
Rotary type positive displacement compressors for petroleum,
chemical & gas industry service.
Recommended practice for classification of locations for Electrical
Installation at Petroleum facilities.
Air cooled heat exchangers
Pressure vessel and boiler code
Process piping
National Electrical Manufacturer Association
American Society of Testing Material
National Electrical Code
Compressor Design Requirement
•
•
•
•
•
The compressor package capacity shall be selected after taking into account the losses
due to air drier purging and leakage losses.
Reciprocating type compressors shall be Non-lubricated, heavy duty industrial,
water cooled type with closed circuit cooling tower.
For screw compressors each compressor shall be fitted with an oil separator for
provision of oil free air of a maximum contamination of 5 ppm.
Each compressor shall be fitted with a relief valve (for each stage) that can not be
isolated, sized for full compressor (stage) capacity.
The package shall be provided with an automatic capacity control system which shall
function by suction throttling (screw compressor).
Air Dryer
•
•
•
A dual air drier set shall be installed downstream of utility air receiver.
The air drier assembly shall be a heatless, solid desiccant type with twin tower each
sized to supply dry air continuously and meet the rated capacity of package.
Regeneration shall be by means of compressed air.
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•
•
•
•
The unit shall be arranged for automatic change over such that one tower is always
under drying and the other under regeneration. Visual indication shall be provided
on local panel to indicate the state of each vessel (drying / regeneration).
The desiccant shall be activated alumina or equivalent.
Adequate openings shall be provided on each dryer vessel to enable the loading /
unloading of desiccant without dismantling the vessels or pipe work.
Sampling provision for air dew point measurement shall be provided.
Vessels
Æ ASME code stamp shall be provided on all pressure vessels.
Æ Corrosion allowance of 3 mm shall be applied for C.S. parts of vessels.
Filters
•
•
Upstream and downstream of the dryer assembly shall be a set of pre-filters and after
filters respectively.
Both filter assembly shall consist of two 100% capacity units each arranged in parallel
& provided with an automatic drainer.
Controls
•
•
Local panel shall have alarm and shutdown devices for high vibration, high
condensate level, low lube oil pressure, high discharge temperature etc. for safe
operation of the unit.
Various process and machine parameters shall be available at the platform DCS.
Testing
•
•
5.6
Compressor shall be performance tested at manufacturers works at their rated speed,
capacity and pressure in accordance with the relevant codes.
All pressure containing parts shall be hydrostatically tested to 1.5 times their
respective design pressure.
STRUCTURAL:
The concept and design of offshore structures are based largely to suit process
requirements, design service life, space and weight of equipments and utilities, water
depth, environmental parameters and geo-technical parameters etc. and the cost of the
structural system is significantly governed by the cost of fabrication, transportation and
installation.
At present in our country in offshore operational areas, fixed offshore platforms are
being constructed for the water depth ranging between 40m & 90m.These fixed
platforms, consists of a large multilevel deck structure supported on template, usually
called a Jacket, is three dimensional welded frame of tubular members and is rigidly
connected to sea bed by means of the piles. The decks provide necessary facilities on
wellhead platforms and for support buildings, compressors, generator, storage tank,
equipment module and related facilities.
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In order to establish the design criteria, the following codes and standards (latest
amendments) are adhered and are globally acceptable:
API RP 2A
Recommended practice for planning, designing and constructing fixed
offshore platforms- Working stress design of American Petroleum
Institute.
AWS D1.1
Structural Welding code of the American Welding Society (AWS)
provides the design guidance for structural welding of tubular members
& joints.
AISC, 9TH Edition
Manual of steel construction, Allowable stress design of
American Institute of Steel Construction.
On the basis of operational philosophy, the platforms are classified into two broad
categories:
The unmanned platforms are those platforms where operator’s intervention is required
normally occasionally for carrying out well testing and maintenance/checking of
facilities. These platforms are of smaller sizes and a conventional platform is having fourlegged jacket sub structure, two major decks (cellar and main) with defined well head
area and building module below the helideck.
The manned platforms are basically process platforms with facilities for processing of
oil/gas gathered from number of well platforms. As such, the process platforms of
multiple facility providers cover large space and heavy structural loads of different
modules installed over decks .In general, these platforms of multilevel deck structure
installed on 6-8 legged jacket structures.
Structural Design Philosophy
The In service analysis consists of In place and fatigue analysis and is performed in order
to find the structural response of the structure during operating life of the platform. The
In-place analysis covers the environment loads response due to extreme loading &
operating loading conditions applied to check the soundness of the structure along with
self, live loads and accidental loads. Loads acting on an offshore structure are added up
in different logical combinations to arrive at the maximum possible loads, which are
likely to occur during the service life. The Fatigue analysis of jacket tubular joints
subjected to repetition of stress due to the cyclic nature of wave loading is analyzed for
fatigue endurance. The deterministic fatigue analysis as outlined in API RP 2A is
performed for the platforms.
The Pre service analysis covers the following activities, which are required from
fabrication yard till the installation is completed.
Load out analysis, (Either by skidding or by trailers). The structure shall be checked for
adequacy for the proposed load-out operation and for the effects of the localized
loadings.
Transportation analysis: The jacket and topsides are checked w.r.t transportation loads
exerted during towing from fabrication yard to the installation site. A dynamic motion
response analysis of barge/ structure system is carried out to determine the maximum
loads imposed on the structure and the sea fastening members during the course of
voyage from fabrication yard to off shore side.
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Lifting analysis: The topside is analyzed for installing by direct lifting from cargo barge.
Jacket will also be analyzed for lift condition during various upending stages for final
installation.
Launching analysis: Monitors the jacket behavior and to check the structural integrity
while launching.
Floatation and upending analysis: Flotation analysis of jacket is carried out using static
interactive approach to calculate the stable equilibrium position of natural floating.
Calculation of individual sling loads, hook loads and ballasting requirements at
successive stages to raise the jacket from its free floating position to an upright position
till the jacket finally set into the sea bed
On bottom stability analysis: For checking the jacket stability and mud mat for
structural integrity, when it is seated prior to piling and during initial piling on defined
Environmental parameters and installation conditions.
Pile drivability analysis: The analysis consists of three definite steps. First, the driving
resistances that can be overcome by a particular hammer- pile –soil system
determination, second the pile wall thickness is adequate & Third, the sectionalistion of
the pile (add-on lengths) from dynamic and static stress considerations.
BASIC LOAD CASES AND LOAD COMBINATIONS:
Load parameters: The design loads for the analysis are considered in the following
categories.
o
o
o
o
o
o
o
o
Dead loads:
All permanent structured modeled as well as non-modeled
structural items of permanent nature come under this category.
Live loads:
The design live loads for local beam/plate design and global
design (truss/framing) are defined in terms of uniform distributed loads over the
areas.
Equipment and piping loads: The dry, operating and hydro test weights of
equipments, piping including pipe supports, electrical cables and trays, and
other machines are covered in this category.
Operating loads:
Covers vessels designed with full of liquids/water,
vessels for gas, gas lines, and liquid lines in full conditions.
Environmental loads complies the following parameters, which are applied on
all structural components during detailed Engineering.
Wave and Current forces: The design wave is treated as a regular wave ‘STOKE’
fifth order theory and is used to compute water particle kinematics, using
apparent wave period computed as per API RP 2A.
Wind forces: The wind forces are calculated taking into consideration shielding
shape coefficients and variation of wind velocity with height as specified in API
RP 2A.Wind are assumed to act simultaneously and collinearly with wave and
current forces. Sustained wind and gust of appropriate duration are used as per
API RP 2A for different global and local analysis of platform components.
Earthquake loading: The earthquake loading on the platform structure shall be
calculated using response spectrum method in accordance with the provisions of
API RP 2A. The response spectrum data for this analysis follows the guidelines
of Zone IV earthquake as given in Indian Standard IS-1893.
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On the basis of environmental parameters, the wave, astronomical tide, current profile
and wind velocities are taken into consideration for design. Defined contingencies are
allowed for any weight variation or inaccuracy in load data during early stages of
detailed engineering. The In place integral-structural analysis of the idealized decksubstructure (jacket)- soil system is performed on different load combinations for
substructure, deck and building modules.
The major loads which are taken into account for combinations are Environmental loads
(Extreme storm wind, wave & current, Operating storm wind, wave & current),
Structural dead loads, Equipment & piping weights, open / UDL live loads, crane dead
and operating loads, riser dead loads, and reaction from modules.
A typical load combination for substructure analysis is as under:
Load combination no. 1 Extreme storm condition with operating loads
Load combination no. 2 Operating storm condition with operating loads
Load combination no. 3 Extreme storm condition with empty equipment to check the
capacity of the piling under the max. Uplift force.
Load combination no. 4 Earthquake with operating load.
Load combination no. 5 Modular rig load with extreme & operating storm
A typical load combination for deck structural and Building frame analysis is as under:
Load combination no. 1
&2
Load combination no. 3
&4
Load combination no. 5
Load combination no. 6
Load combination no. 7
Extreme storm condition with operating loads
Operating storm condition with operating loads
Normal operating loads plus crane operating load.
Earthquake with operating loads.
Modular rig load with extreme & operating storm
Individual panels of jackets and decks are separately analyzed as required to check their
integrity. Stresses and deflections up to Allowable limits are permissible in confirmation
to those allowed in API RP 2A or AISC. The structures are designed safe for all stages of
in service, and pre service stages (viz. load out, transportation, floatation and upending,
on bottom stability, pile drivability) and fabrication.
Seabed Features:
The Jackets are designed for seabed slope and to meet the installation tolerances. If the
seabed slope is such as to tilt the Jacket by an angle exceeding 25 minutes, the slope is
considered in design. Design of the Jackets also considers mudslide, if any. If the slope in
seabed is such as to tilt the structure by an angle exceeding 1 in 100, the detail design
takes into account the slope in seabed in the form of adjustment in framing and/or
mudmat elevations.
Platform Configuration:
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The platform is sized and designed in accordance with the approved equipment layout
and arrangement. The equipment weights, sizes, clearances, and space requirements for
personnel movement and maintenance purposes, are considered for the determination of
platform size and equipment arrangement, and necessary provision is kept in the layout.
The consideration in HAZOP study is incorporated.
Installation Philosophy:
Generally, the Jacket and Topside modules are installed offshore by derrick barge. Such
type of lift installation is highly economical.
Water Depth:
For the design of substructure appurtenances, a provision for the variation of ±1.0m in
the actual water depth is usually allowed.
Marine Growth:
All the framing braces between the jacket level and the first horizontal level are fitted
with an ocean powered marine growth prevention system. The design of platforms
generally includes full allowance for marine growth on all members of the jackets and
appurtenances including risers, caissons etc.
Geometrical Considerations:
The top horizontal framing of the substructure is designed to be at a minimum elevation
above chart datum level, so as not to be in wave splash zone. Minimum air gap
requirement as per API RP 2A is also considered.
Structural Analysis:
All structural analysis is performed using a suitable structural analysis computer
programme. The datum for the axes is the Platform Datum. The modeling techniques
used are chosen appropriate for the structure, the analysis being undertaken and normal
industry practice. All analyses utilize the same base model. That is, the in-place model
forms the basis for all the other analyses to be performed.
The in-place analyses includes a combined Jacket and Topsides model to ensure the
correct soil pile-structure stiffness interaction.
Non-linear pile foundations to the Jacket are considered for the analysis and design of the
jacket.
The Jacket model considers the effect of environmental loads on the appurtenances
including anodes, boat landing, barge bumpers, conductors, risers and riser guard etc.
All structural analyses are performed using a suite of programs applicable to the design
of offshore structures. The analyses demonstrate the adequacy of the structures under all
envisaged phases and anticipated loading. Analyses generally include, but are not
limited to:
IN-SERVICE CONDITION
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•
•
•
•
•
In-place operating and extreme storm
Foundation Design- Pile Analysis & Design
Fatigue
Seismic
Accidental loads (The scope is of which is generally determined by the Contractor
and approved by the Company following the Platform Safety studies)
PRE-SERVICE CONDITION
•
•
•
•
Fabrication
Loadout
Trsnportation
Installation
a. Jacket structures (launch, flotation and up-ending, OR lift)
b. On Bottom stability
c. Piles (stick-up, drivability)
• Topsides Lift
Seismic Data:
The earthquake loading on the combined jacket and topsides structure is calculated using
the response spectrum method and in accordance with the provision of API RP 2A. The
response spectrum data for this analysis generally follows the guidelines for Zone-IV
earthquake area as given in Indian Standard IS-1893.
Corrosion Protection:
All structures are designed to resist corrosion in different zones. As per API RP 2A,
additional material thickness as corrosion allowance for structural members and other
components in the splash zone are provided as follows:
Item
Submerged Zone
Splash Zone Barge Bumper
Boat Landing
Other
Atmospheric Zone
Corrosion Allowance Thickness (mm)
0.0
6.0
6.0
13.01
0.0.
Note: All structure, caissons, pump casings, etc. the corrosion allowance shall apply over
the entire component.
All steel surfaces in the submerged zone are protected against corrosion by a sacrificial
anode system. The design is as per specification for cathodic protection. All pipelines
and risers shall be properly insulated from CP System.
All steel surfaces in the splash zone and atmospheric zone are painted in accordance with
the respective project specification. All equipment, stairways and appurtenances such as
barge bumpers, boat landings, riser protectors etc. including their stabbing guides are
painted irrespective of the applicable zone.
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Areas and joints, which are inaccessible for maintenance and thereby susceptible to
corrosion, are suitably sealed by methods such as boxing with plates etc.
Design Loads:
The design loads generally applicable to Jacket and Topsides are as follows:
1.
Structure Dead Loads
The structure dead loads include the weight of all deck plate, grating, and
secondary steel, deck beams, girders and trusses.
2.
Equipment Loads
Equipment loads include the weight of all equipment, bulks, piping. These loads
are to be developed based on equipment layouts. Two basic load conditions are
considered for global design. These are:
•
•
•
3.
Equipment & Piping Dead Weight
Equipment & Piping Operating Contents Weight
For local design, hydrostatic test weights shall be considered where
applicable.
Crane Loads
On the basis of the Crane requirement and the data provided by the crane
manufacturer, the static and dynamic crane loads are determined. The dynamic
crane load cases generally consider a range or boom direction to ensure all
possible lifting scenarios are adequately checked. A minimum of eight boom
directions are considered.
4.
Live Load for Local and Global Design:
Local and global live loads are used in the in-service analysis. The magnitudes of
local and global live loads to be used vary from project-to-project, and these are
specified in the bid package of every new platform.
5.
Open Area Live Load:
The Open Area Live Loads are applied to all clear unoccupied areas of deck and
internal areas of the Utility and Equipment rooms. The Open Area live loads are
used in conjunction with equipment and crane loads for the design of primary
and major secondary steelwork. Open Area Live Loads are generally combined
with equipment weight data, from the weight control report and/or when
provided by the Suppliers.
6.
Wind Loads:
Wind loads are calculated according to the requirements of API RP 2A. The
wind areas for global design of the Topsides are calculated assuming that the
area between the decks is fully enclosed. Wind areas are also included for
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equipment items on all decks. The following are considered in the calculation of
wind loads:
a) A minimum of eight storm directions is considered for each load case for the
extreme storm and operating storm conditions.
b) Wind is assumed to act simultaneously and collinearly with wave and
current forces.
c) Wind speeds are adjusted for elevation and gust duration, in accordance
with API RP 2A
7.
Wave & Current Loads:
Environmental parameters, specific to a location are applied to maximize loading
on all structural components. Analysis is performed for wave approach along
grid directions and selected diagonal directions. For each direction of approach,
the more severe of the environmental parameters of directions adjacent to it are
selected. A minimum of eight storm directions is considered for each load case
for the extreme storm and operating storm conditions. Waves and current shall
be considered concurrent with wind.
The design wave is treated as a regular wave. 'Stokes' Fifth Order theory’ is
used to compute water particle kinematics, using apparent wave period
computed as per API RP 2A. Wave kinematics factor, as given for each project,
is used to account for wave directional spreading or irregularity in wave profile
shape.
The current speed in the vicinity of the platform is reduced by the current
blockage factors.
The wave particle kinematics multiplied by the wave
kinematics factor and the current velocities, adjusted for blockage, are added
vectorially to obtain total velocity vector at any point. The given current profile
is treated as applicable to water depth equal to still water level. For any other
water level at different points along the wave, the velocities are calculated based
on linear stretching of the current profile. Morison's equation applied to only
the normal components of velocity and acceleration is used to compute normal
wave forces on the individual members. The coefficients of drag and mass
(inertia), Cd and Cm values are considered as per API RP 2A.
8.
Fabrication Loads:
All structures are checked for the loads applied during fabrication. Details of
such loads and the structure support points are generally determined during the
fabrication. Consideration is given to the support points used for weighing and
load out. Wind loads are included with this load condition, appropriate for the
site location.
9.
Load-out Loads:
All structures are checked for the loads applied during load-out. The proposed
method of load out is generally skidded, trolleyed or lifted. The following is,
however, considered:
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a) Dry loads are only used, together with weights for all preinstalled lifting
gear, sea-fastenings, loose ship items, etc. The loads are based on the Weight
Control Report.
b) For lifted Load out, Lift Installation Loads as described below are used.
c) For skidded or trolleyed load out:
•
•
•
A minimum horizontal racking load of 15% of the total load on one
skid rail is applied.
Total loss of vertical support at one support location with the structure
being supported by the remaining support locations only. The vertical
deflection at the un-supported leg need not be more than 25 mm
Wind loads for a return period of 1 year are included appropriate for
the site location.
Structures are loaded out onto the transportation barge by means of launch
ways, continuous or discrete skids or wheeled dollies. The structures are
checked for adequacy for the proposed load out operation and for the effects of
the localized loadings resulting from change in slope of launch ways / tracks and
the change in draft of the transportation barge as the structure moves on to it.
For substructure structures loaded out on launch cradle this analysis covers the
front end of launch cradle unsupported for various distances (barge moves
downward), and two ends of the launch trusses supported (barge moves
upward).
For structures loaded out on discrete skids or wheeled dollies, the analysis covers
cases due to loss of support of one or more supports, including three point
support conditions.
For other means of load out the analysis is based on the support conditions likely
to be experienced.
If the support conditions envisaged during weighting of the deck/module are
different from those considered for loadout analysis, a separate analysis is
performed with appropriate support conditions to ensure adequacy of the
structure during weighing operations.
10. Transportation Loads:
Preliminary transportation Analysis:
All structures are checked for the inertia loads applied during sea transportation.
Consideration is given to the support points used for sea fastening.
The
following points are also considered:
•
•
Dry loads only, are used, together with weights for all preinstalled lifting
gear, sea fastening, loose ship items etc. The loads are based on the Weight
Control Report.
For the preliminary transportation condition, in lieu of a detailed
transportation and barge motions analysis, the following inertia loads are
used:
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Barge Type
Small cargo barge (76 m
LOA or 23m beam)
Large barges
•
•
•
Single Amplitude (in 10 Sec. Period)
Roll
Pitch
Heave
25º
15º
1.0g +/- 0.2g
20º
12.5º
1.0g +/- 0.2g
The center of rotation is assumed to be 60% above barge keel at longitudinal
midship of the transport barge.
The transportation inertia loads are combined as roll ± heave and pitch ±
heave. Quartering seas are generally not considered.
Wind loads for a return period of 10 years (1 minute mean) are included with
this load condition.
Detailed Transportation Analysis
The design of all structures is done so as to accommodate the forces imposed
during transportation. The computer analysis is performed in accordance with
the ABS or any other International Certifying agency rules along with the
provisions given therein.
The final transportation analysis consists of the following:
Static Stability of barge/structure system:
a) Intact condition
b) Damaged condition with at least any one compartment of barge flooded.
Sustained wind speeds of 148 kmph and 93 kmph are considered for
calculating the wind forces on the barge freeboard and cargo’s surface area
for Intact and Damaged conditions respectively. Wind forces are calculated
as per ABS Rules.
Dynamic motion response analysis for barge/structure system:
In order to determine the maximum loads imposed on the structure and sea
fastenings during the course of voyage from fabrication yard to offshore site an
analysis of the dynamic motion response for the structure/barge system is
performed. This analysis generally includes the following phases:
The following are considered for the route specific dynamic motion analysis:
a) Wave direction: Beam, Head and Quartering Seas.
b) The maximum sea state to be considered depends upon route of tow and
season of tow.
c) The environmental conditions to be considered are based on an average
recurrence period of not less than ten years for the season of year when the
tow will take place.
d) In order to obtain the maximum acceleration response, at least three sets of
periods are chosen for the maximum sea state for each direction of approach
depending upon the dynamic characteristics of the barge/structure system
and the towing speed of barge.
e) A reduced wave height (less than the maximum)/period combination, if
that is likely to result in near resonant response conditions.
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After obtaining the maximum response for various sea states, the structure is
analyzed for the corresponding maximum inertia/gravity forces.
Based on the above analysis, the Contractor carries out the design of sea fastening
and the preparation of detailed sea fastening drawings.
11. Lift Installation Loads:
All structures are checked for the loads applied during lift installation off the
barge and into position in accordance with API RP 2A. The following points are
also considered:
Æ Dry loads are only used, together with weights for all preinstalled lifting gear,
sea-fastenings, loose ship items, etc. The loads are based on the Weight
Control Report.
Æ A dynamic factor of 2.0 is applied to the lift weight of the item for the design
of lifting frames, pad eyes and adjacent members.
Æ A dynamic factor of 1.35 is applied to the lift weight for all other members
transmitting lifting forces.
Æ Where a four sling arrangement is used to lift the item, the analysis is carried
out in two cases, one assuming all slings equally effective i.e. each diagonal
carries 50% of the static lift weight and another with one diagonal sling
carry 75% and the other diagonal sling carry 25% of the static lift weight.
Æ Rigging is designed to limit the swing of the lifted objects to within 2 degrees
from horizontal about any axis. Static equilibrium during the lifting
operation is ensured.
Æ Structural deflections are limited for deflection sensitive equipment, buildings
and other items.
A complete three-dimensional idealized mathematical model of the structure is
analyzed for the stresses developed during lifting operation to comply with the
provisions of API RP-2A.
During Detail Engineering the contractor performs a lift study to establish that
the modules as conceived are liftable with the proposed barge crane. This study
includes adverse combinations of variation in centre of gravity and weight. The
lifting scheme including requirements of spreader frame is finalized based on
this study. The weight control report generated forms the basis of the study.
A three-dimensional space frame lift analysis is also performed for all structures
to be lifted.
The lifting analysis is carried out as per provisions of API RP 2A. The load
combination includes appropriate skew load distribution between the two
diagonal pair of slings to account for sling length variation.
If the subsequent weight control reports / actual weighing of the module
indicate a weight increase of more than 5% and / or a shift in centre of gravity of
more than 2% of the corresponding linear dimension, a revised lift analysis is
carried out to ensure that the permissible stress are not exceeded due to the
revised weight / centre of gravity. The analysis is also repeated if the framing
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arrangement of lifting scheme, spreader frame arrangement or components to be
lifted is revised to an extent to affect the stress distribution in the structure.
Deflections are to be limited for structures with deflection sensitive
appurtenances.
12. Other Installation Loads:
All structures and structural components are checked for all of the loads likely to
be imposed during all phases of the installation. The imposed loads are
considered appropriate to the method of installation.
Jacket Launch: Three dimensional launch trajectory analyses consider the
following variation in basic parameters:
Æ Launch Weight -3% to + 5% of the weight defined in the Weight Control
report
Longitudinal Centre of Gravity is offset to 1% of length of jacket towards top of
jacket
Æ Barge Trim is –50% to +50% of the selected trim
Æ Coefficient of Friction for skid rails is (+) 25% of estimated value
Æ Higher values of variation in the above parameters may be studied if so
required
Æ Sufficient combinations of the above basic parameters are analyzed to produce
the worst-case launch scenario.
Æ A minimum mudline clearance of 10.0m at both top and bottom of the jacket
shall be ensured during the entire launch operation.
The Jacket member and joint stresses are checked for code compliance during all
phases of the launch
Members with longitudinal axis, which enter the water within 15 degrees of
horizontal, are checked for slam effects using predicted velocities from the
launch analysis.
Jacket Flotation and Upending: Flotation and Upending analyses are performed
to investigate the stability, bottom clearance, derrick vessel hook loads and
buoyancy requirements at successive stages of the Jacket installation. A
minimum bottom clearance of 3.0 m is maintained throughout the upending
operation. A minimum reserve buoyancy of 12% over the estimated weight is
ensured in the design. With any one buoyancy component fully flooded, the
reserve buoyancy is designed to be a minimum of 6%.
Jacket on Bottom Stability: A rigid body stability analysis is performed for the
Jacket to ensure stability before pile installation. Both still water and installation
environmental conditions are considered. The Still Water Level is considered as
LAT + 50% of Astronomical Tide. For the on-bottom weight the jacket is
considered in all its applicable set down ballast and stabbed hanging pile
configurations. The steel mudmats are sized to provide bearing and sliding
resistance. Any slope in the seabed is taken into account. The ultimate bearing
capacity of the mudmats under combined vertical and horizontal loading is
calculated using the methods in API RP 2A. Pile sleeve extensions or skirts,
where applicable may be used to enhance the mudmat capacity. Critical wave
heights are determined and checked against installation environmental
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conditions for jacket. API safety factors of 2.0 for bearing failure and 1.5 for
sliding failure are applied.
13. Stab-in Guides and Installation Aids:
All stab-in guides and bumpers are designed for the following loads, as a
minimum:
•
•
Horizontal impact force = 10% of the static weight of the item.
Vertical impact force = 50% of the static weight of the item.
14. Earthquake Loads:
The earthquake loading on the combined Jacket and deck structure is calculated
using the response spectrum method and in accordance with the provisions of
API RP 2A. The response spectrum data for this analysis follows the guidelines
for Zone-IV earthquake area as given in Indian Standards IS-1893. The
importance factor is taken as 2.0 and the coefficient to account for the soil
foundation system is taken as 1.2. Contribution of the marine growth in the
added mass is also considered in the analysis.
For building / equipment / modules, an equivalent static analysis is carried out
with a horizontal seismic coefficient of 0.12.
Earthquake Forces wherever applicable are taken as occurring in both the
direction and 50% in the vertical direction.
Equipment Support & Services
All equipment supports, pipe supports and other services support steelwork are
designed to withstand the operating and hydrotest loads specified on the
Supplier documents.
For the transportation condition, in lieu of a detailed analysis, the following
inertia loads are used as a minimum design case:
Horizontal acceleration = 0.7 g
Vertical acceleration= 1.0 g +/- 0.20g
Barge Bumpers
The Barge Bumpers and their associated connections to the Jacket are designed
for the following loading:
a) Vessel impact directly in the middle 1/3 height of post. Energy to be
absorbed in the system is 30.4 tonne-metre.
b) Vessel impact lateral in the middle 1/3 height of post. Energy to be absorbed
in the system is 11.0 tonne-metre.
Boat Landing
The Boat landing and its associated connections and local framing are designed
for the following load combinations:
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i.
ii.
iii.
iv.
Dead load + Live Load of 5.0 kPa on each landing
Dead Load + Boat impact load at different points on the berthing face
Dead Load + Extreme environmental load.
Installation Loads.
The energy to be absorbed in the system from vessel impact is 3.0 tonne-metre.
Wave Slam:
Horizontal members in the wave zone are designed for wave slam forces in
accordance with API RP 2A. Bending stresses due to both horizontal and vertical
slam forces are investigated. One-third increase in permissible stress is allowed.
However, the current velocity components are not included in the wave
kinematics when calculating wave slam loading. For X-braces, members are
assumed to span the full length. Member lengths are reduced to account for
Jacket leg ratio.
Permissible Stresses & Factors of Safety
The permissible stresses and factors of safety are generally as recommended in
API RP 2A.
Load Contingencies, Mill Tolerance & Weld Metal
It is required to accurately calculate the pre-service and in-service design loads
consisting of dead loads, piping and equipment loads (empty and operating),
topside modules, utilities and any other loads to which the system will be
subjected during fabrication, transportation, installation and operation etc.
A minimum of 3% weight allowance to account for mill tolerance and weld metal
is applied for all analyses. This allowance is added to the estimated substructure
and superstructure dead weight.
In the preliminary analysis stage and till the accurate estimation of loads is
arrived, the platform in-service and pre-service design loads, applied either
globally or locally, includes contingencies estimated over and above the
estimated loads.
Jacket Fatigue Design
The tubular joints of the Jackets are analyzed for fatigue endurance in accordance
with API RP 2A. A deterministic fatigue analysis using Palmgren-Miner’s Rule
is used to predict the fatigue lives of structural connection.
Dynamic analysis is carried out to predict the fundamental periods of the
platforms in order to confirm the sensitivity of the structure to wave induced
excitation. The fundamental sway periods are used to derive the dynamic
amplification for the in-place analysis loading conditions.
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Fatigue analysis is performed for the Jacket structures using methods
appropriate to the sensitivity to dynamic loading. A deterministic approach is
deemed adequate for platforms with fundamental period less than 3 seconds.
Fatigue Life: The in-service fatigue design life of the joints is designed to be at
least two times the service life of the platform.
Analysis Procedure: The fatigue analysis is performed for all joints, which
determine the safety and reliability of all the steel work of the structure.
Particular attention is paid to joints in the top one-third of the substructure
structure including deck legs and the bottom horizontal brace level. For each
joint and type of failure under consideration the stress range spectra is computed
at a minimum of 8 positions around the joint periphery to ensure that the point
of maximum damage and hence lowest fatigue life is considered. For
computation of fatigue damage, the stress range versus wave height diagram for
each wave approach direction is divided into (a minimum of 10) blocks (of 15
cm) and the damage computed for each block and summed up. For each circular
tubular joint two types of failure are considered, using the appropriate stress
concentration factors - Brace to weld failure and chord to weld failure. For joints
other than those between tubular members, individual detailed consideration is
given with due regard being paid to publish, reliable experimental data.
Stress Concentration Factors (SCF): The hot spot stresses ranges at the joints on the brace
and chord side of the weld, used to estimate the fatigue lives, are determined from.
Hot spot stress range = Fra, SCFa + FRi.SCFi + FRo.SCFo
Where, FRa, FRi and FRo are the brace nominal axial, in-plane bending and out-of-plane
being stress ranges and SCFa, SCFi and SCFo are the corresponding stress concentration
factors for axial, in-plane bending and out-of-plane bending stresses for the chord side or
the brace side.
The fatigue life on both the brace and chord side of the weld is calculated with one of the
following methods for obtaining the stress concentration factor applied to the brace
nominal stresses:
For K Joints: Formula proposed by J.G. Kuang et al “Stress Concentration in
Tubular Joints” (Society of Petroleum Engg. Aug. 1977).
For T, Y and X Joints: Formula proposed by A.C. Wordsworth and G.P. Smedley
“Stress concentration in Unstiffened Tubular Joints” select seminar on European
Offshore steel Research, November 1978.
S.N. Curves: The basic S-N curves to be used in the evaluation of fatigue life are the API
X-prime curve. The thickness correction effect as specified in API RP 2A is applicable.
The use of X-curve, with corresponding joint preparation as per API RP 2A is acceptable
for joints that do not have a computed fatigue life greater than half the required fatigue
life when the X-prime curve is used.
Marking of Joints: The joints are to be identified with the computed in-service fatigue
life less than four times the service life of the platform. These joints are marked with
neoprene based Cupro-Nickel embedded sheets for future inspection purposes.
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Identification marking is designed to be easily accessible for divers and a minimum gap
of 250mm is maintained between the identified joint and the marking.
MISCELLANEOUS DESIGN
Structural design generally conforms to the relevant codes in particular API RP 2A and
AISC. Structural design is based on working stress methods. Where code checks are not
applicable, allowable stresses are computed using rational procedures and appropriate
factors of safety. Major rolled shapes are designed as compact sections as defined by
AISC. The minimum thickness of structural plates and flange/web thickness of sections
are generally 6mm. All deck plate is chequer type with a raised pattern surface and the
minimum thickness is 8mm. The minimum thickness of Jacket tubulars is 10mm except
in the splash zone where 25mm is used. The minimum thickness of deck truss tubulars is
8mm. Clear span of plating and grating is designed not to exceed 1200mm. Vibration is
considered for any structure supporting major rotating machinery. The structure is
designed so that the natural frequency of the supporting structure is less than 70% or
greater than 140% of the equipment operating frequency. Member stresses due to aspects
which are not specifically covered in the computer structural analysis are investigated by
manual calculations and results combined with computer results to ensure that the stress
and deflection limitations are not exceeded. All major structural members are designed
to meet the following guidelines:
a.
Member slenderness ratio: K1/r <100. The buckling coefficient K, is chosen for each
member in accordance with API RP 2A recommendations.
b. Tubular member diameter to thickness ratio: 20 < D/t <60.
c. Pile diameter to thickness ratio: D/t <60.
d. Use of sections back-to-back, battened and lattice type built up sections is not
permitted, in order to avoid areas difficult for maintenance.
Connections: All connections are designed as welded joints. The joints required for
removable type structural members are generally considered as bolted joints.
Tubular Joints: Tubular joint design and detailing for both pre-service and in-service
conditions are in accordance with API RP 2A and are designed and detailed as simple
joints. Where overlap cannot be avoided, the minimum overlap is determined as per API
RP 2A.
Non-Tubular Joints: Hybrid joints, combining rolled wide flange sections with tubular
sections as used in module trusses, plate girder or wide flange joints are designed in
accordance with AISC using rational engineering methods. Truss brace to chord joints
are designed for transfer of axial loads from one brace to another across the truss chord
in shear. The web stiffeners are designed to carry in compression the permissible axial
tensile load of the brace.
Ring Stiffened Joints: Appropriate closed ring solutions are used to design launch leg
ring stiffeners at deck leg/girder intersections as per the provisions of API RP 2A. Cross
joints, Launch leg joints and other joints in which the load is transferred across the chord
are designed assuming an effective width of the chord equal to 1.25 times chord
diameter, on each side from the centerline of the extreme incoming braces, or length of
the can whichever is less.
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Deflections: Deflections are limited to criteria, based on equipment operating
requirements, specified by equipment suppliers or the following, whichever is less:
•
•
•
Deflections are checked for the actual equipment live loads and casual area live loads
Pattern loading shall be considered.
Deflection of members supporting deflection sensitive equipment is not greater than
1/500 for beams and L./250 for cantilevers.
Deflection of other structural members are designed not to be greater than L/360 for
beams and L/180 for cantilevers, where “L” is the effective span of the member.
Design Philosophy:
The Jacket and Topside are designed to withstand the extreme storm and operating
storms that occur in the Mumbai High South area of the Arabian Sea. Structure Analysis
and design is generally in accordance with the requirements of API RP 2A and/or AISC
using working stress design methods.
Primary and major secondary steelwork for the Topsides modules and Jacket (including
foundation) are proportioned to ensure adequate strength and serviceability throughout
all facets of installation and in service conditions.
Primary steel includes:
Topsides – All truss members, deck girders, crane pedestal (if specified) and deck legs.
Jacket – All legs, vertical / inclined bracing, horizontal bracing, launch truss (if required)
and piles.
Topsides secondary steel includes deck plate, grating, deck beams/stringers, equipment
support beams, walkways, stairs, and hand railing.
Jacket secondary steel includes cathodic protection, boat landing, barge bumpers,
walkways, casings and caissons, appurtenances and their supports and mud mats.
Deck Plate and Grating Design: The local design of deck plating and grating is based on
the applicable loads. Spans of plate and grating shall not exceed 1200mm. Plates are
reinforced if concentrated loads are directly placed on plating. Grating Design is for a
maximum deflection restriction of L/200 or 6 mm whichever is less. Bearing member is
minimum 30 mm X 5 mm serrated type spreader at 30 mm center to center. Steel cross
bar is minimum 8 mm diameter high strength deformed bar spaced at 75 mm center to
center. Each bearing member is serrated by making a hole of 10 mm dia. at 15 mm center
to center at top end and depth of hole shall be 8 mm to match with 8 mm dia. bar top.
Gratings are galvanized as per project protective coating specification.
Beam and Plate Girder Design: The local design of beams and plate girders is based on
the applicable loads defined for the project. These are designed in accordance with
AISC’s specification and incorporate the following guidelines.
Æ All plate girders are compact sections as defined by AISC.
Æ Web, Top and bottom flanges at a given section are of the same grade of steel and
symmetric about the beam’s axes.
Æ These are also checked for loading due to hydro test conditions.
Æ Deflection is limited to the criteria listed above.
Handrails, Walkways, Stairways and Ladders: Handrails, walkways, stairways and
ladders are designed as specified below:
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Æ Handrails are provided around the perimeter of all open decks and on both sides of
stairways.
Æ Handrails around the perimeter of laydown areas, loading and unloading areas are
removable type.
Æ The top rail of the handrail is supported at maximum 1500 mm intervals.
Æ Handrails are designed to withstand 100 kg concentrated load acting vertically or
horizontally at any point.
Æ Handrails in the wave zone are designed to withstand extreme storm maximum wave
loading.
Æ Walkways, stairways and landings are designed for the following load combinations.
i. Dead load + live loads
ii. Dead load + extreme storm three second wind gusts and/or extreme storm
maximum wave whichever is applicable
Æ Stairways are made of structural steel, double runner with serrated bar grating treads
and handrails.
Æ The minimum clear width of stairways and walkways is 1000 mm.
Æ Walkway and stair tread grating are designed to be replaceable.
Handrails: Handrails of height 1100 mm height with three horizontal tubular and one
100 mm X 6 mm kick plate are provided around the perimeter of each deck (except the
helideck), both sides of stairways, sides of walk ways in Jacket level and side of helideck
walk ways. Handrails around loading/unloading areas are made removable to allow
loads on hoists to pass.
The preferable types of handrails are as follows:
SL. NO
1.
2.
3.
4.
TYPE
Type - I
Type – II
Type – III
Type - IV
Detail of hand rail type
HR below Cellar deck (wave zone) fixed type.
HR on and above Cellar deck fixed type.
HR on and above Cellar deck removable type.
HR with safety chain.
The preferable member size for different handrail are as follows:
MEMBER
Type –I vertical post and top
horizontal member
Type –I other horizontal member
Type –II, III, IV vertical post and
horizontal member
Type – III Socket, Collar
Kick plate
Coaming angle
Safety Chain
INDIAN
STANDARD
--48.3Φ X 5.08
INTERNATIONAL
STANDARD
60.32 X 5.54 , 80s
ASTM A316L
48.26 X 5.08 , 80s
ASTM A316L
1.9” X 0.2” XS
60.3Φ X 3.91
100 X 6
100 X 100 X 8
6 mm
2.5” X 0.154” Std
100 X 6
100 X 100 X 8
6 mm
---
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Removable type handrail is fitted with Socket/Collar. The Socket/Collar is fitted with
Kick plate. Fixed handrail is fitted with kick plate at lower level. Kick plate 100 x 6 mm
ASTM A316L is provided at lower level for handrail Type –I.
Walkways, Stairways and Landings: Stairways are designed with adequate width to
maneuver a stretcher up and down the stairs. Preferable riser height is between 200 mm
to 230 mm and width of trade is 230 mm. Trade is generally of 30 mm thick grating. All
stairs extending to the substructure walkway level are adjustable in length to suit site
conditions. Handrails are provided on both sides of the top of the substructure walkways
Handrails, kick plates, walkways, stairways, and landings and grating for the Boat
Landing and Sea Deck Walkway are of ANSI 316L stainless steel. This includes gratings
for treads and handrails of staircase from Boat Landing to Spider/Sea Deck and
Spider/Sea Deck to Cellar Deck. These are fastened to the structure by a bolting system
carefully designed for the salt-water corrosive environment and not welded. Stainless
steel bolts are not used for this duty. Rough edges on the stainless steel grating are
removed to avoid hazards to personnel.
Access Platforms: Access platforms are provided, where required to allow personnel
easy and safe access in elevated locations. Access platforms are designed for live loads
and any piping or other imposed loads.
Cranes: Based on the scope of work, the crane pedestals and the supporting structure are
designed in accordance with API RP 2A and API SPEC 2C except that the impact factors
conform to design requirements for the cranes. The supporting structure is defined as
the pedestal and all members directly connected to the pedestal. The deflection of the top
of pedestal from the supporting deck is limited to H/200 under design loads, where H is
the height above the deck. The material for pedestal is selected to meet or exceed the
requirements of API Spec 2H Gr.50 steel
Fire Walls: Firewalls for Utility Room walls, ceilings and floors shall be determined
following the platform safety case/risk assessment studies. The fire protection system
for firewalls is designed to comply with the specification Passive Fire Protection for
Structural steelwork on offshore platforms.
Skid Shoe Design: The skid shoes are designed such that the module reaction forces are
spread evenly onto the skid rail. The skid shoes are designed to meet the dimensional
requirements of the skid rails in the construction yard. At the tugging points, a safety
factor of 2.0 is applied to the attachment points and the structure local to the attachment
point. Consideration is given to the effects of any eccentrically applied loads. For
design, the friction breakout coefficient for the shoe wearing timber on a steel skid rail is
assumed to be 0.5 and the coefficient or sliding friction is 0.25. No increase in basic
allowable member stresses is permitted.
Sea fastenings: The design of sea fastenings accommodates the anticipated loads during
Transportation.
Hydrostatic Collapse: All buoyant member including buoyancy tanks are checked for
hydrostatic collapse during the pre service conditions for higher of the two following
cases:
Æ Maximum water depth reached during pre service operations, with a factor of safety
of 2.0
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Æ Accidental complete submergence condition i.e. hydrostatic pressure at mud level
with a factor of safety of 1.5
Tubular members are checked for in-service condition for hydrostat pressure and in
service stress interaction as per API RP 2A. The factor of safety for axial compression
case is taken as 1.5 and 2.0 for extreme and operating environmental conditions
respectively. For earthquake condition the factor of safety for axial compression case is
taken as 1.2
Jacket & Topsides Installation Aids: Installation aids are designed to suit the proposed
method of installation for the anticipated function and leads and the requirements of API
RP 2A
Substructure Installation Aid:
Flooding System
Flooding system is made suitable and reliable for the jacket legs or buoyancy chamber for
controlled flooding of the jacket during upending and placing on bottom.
Grouting System
Pressure grouting system or Single stage grouting system with packers/grout seals is
used. The system is designed as a fail-safe system to cater for all possible
contingencies/eventualities such as failure of any of the components. Each of the
grouting systems adopted has provision for alternate means of grouting in case of failure
of the planned system. In case substructure leg extensions are provided in design, the
grout inlet is taken below mudline just above the packer and the grout line is designed to
have a protective casing upto mudline. Only inflatable grouting packers of proven
design are acceptable. Properly sized air supply lines extend from each of the grout seals
to the substructure top level. All inflatable packers are provided with a rupture disc
installed above the inflating connections to prevent premature inflation of the packer by
hydrostatic pressure in the event of inflation line getting damaged during substructure
installation. Passive Grout Seals of proven design are also sometimes used as an
alternative to inflatable grout packers. Two seals are provided at each location. Suitable
arrangement is provided for collection of return grout from the annulus, in case the
pressure grouting system is not utilized.
Buoyancy Tanks: Buoyancy tank’s supports are designed to withstand the effect of
maximum hydrostatic pressures and slamming forces during dive.
Skirt Pile guides: Skirt Pile guides are designed for the loads imposed during the
installation of the skirt piles. As a minimum, following criteria are considered for the
design of the skirt pile guide and the supporting framework:
a) Top Level:
1.5 times the weight of the lead pile section. The total weight of all pile add-on
sections supported at this level during piling operation. 0.25 times the weight of the
lead section applied lateral to the plane of the supporting frame.
b)
Second Level: The weight of the pile, which will initially pass this level.
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c)
Subsequent Level: 0.5 times the weight of the pile, which will initially pass these
levels.
d) Pile Stabbing Guides: Stabbing guides are designed to facilitate centering and
alignment and to provide effective support to pile add-on sections.
e) Chaser Pile and Pile Connections: Adequate pile connectors are used to assemble
chaser pile segments and ensure a sound connection of the chaser with the skirt pile.
Positive type of connectors is used to drive skirt piles.
f) Upending Pad eyes: Upending pad eyes are designed for the maximum sling load
computed during the upending operation. A lateral load of 5% of the static sling
load is applied in addition to the lateral load computed during the upending
operation. This load is applied at the edge of the outer check plate. A load factor of
2.0 is considered for all the above loads. The orientation of the lower set of padeyes is
fixed by taking into account the variation of the angle of sling with rotation of the
substructure during successive stages of upending operation.
g) Lifting Padeyes: Lifting Padeyes are designed as per API RP 2A. The substructure
legs are designed to have ring stiffeners at these locations to prevent ovalising of the
tubular.
Design of Installation Aids for superstructure: All installation aids are designed to suit
the method of installation for the anticipated function and loads.
Applicable
requirements of API RP 2A are followed.
Lifting Eyes / Trunnions: Trunnions are used for lifting points with a static sling load of
over 600 tonnes. Lifting eyes are designed as per requirements of API RP 2A. The
design sling load is computed based on an assumed tilt of 2º in the most adverse
direction. The lifting eye / trunnions design includes sufficient reserve strength to allow
for future weight growth, load distribution changes and final selection of rigging.
Spreader Frames: Spreader frames are generally connected to the modules by slings. If
rigid legs are provided, then they are adequately braced to carry sway forces.
Bumper Guides: Bumper guides are provided on superstructure to arrest the sway of the
module being installed over it and to position the module accurately. The guide system
configuration and design are such that the guide system elements fail prior to any
damage to the module or the support structure, and the connections to the support are
stronger than the guide elements. The guide system is designed for a Normal load of 10
percent of the module weight in the direction of guide support and a friction force of 3
percent of the module weight in the lateral direction acting simultaneously. Basic AISC
permissible stresses are used in the design.
Boat Landing: Boat landing is provided in minimum three steps with minimum
stepping of one-meter between high and low tide variation with suitable ladder. Boat
landings associated connections, and local framing are designed for boat impact loads,
environmental loads, uniform live loads and dead loads. For structural design the load is
treated as a concentrated load. Mooring bollards are provided near each end of the boat
landings for supply vessel mooring. Two swing ropes are provided near the mid point of
each landing, one at the face of the landing and the other 1 metre seawards of the landing
face and about 1 meter apart horizontally. Swing ropes are supported from the lower
deck structure. Proper arrangements for replacing the swing ropes are provided. The
boat landing is detailed such that there is no interference with other items of substructure
such as risers, barge bumper etc. during installation of operation. In case of boat landing
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designed to be field installed, it is designed to allow a +/- 1 .0 m elevation adjustment to
compensate for variation in the installed height of the jacket. The boat landing is
designed as removable and readily replaceable. Members are allowed to form plastic
hinges under design impact forces.
Barge Bumper: For structural design the load is treated as a concentrated load. Local
denting of the vertical post is neglected. Members are allowed to form plastic hinges
under the design impacts forces. The barge bumpers are designed as removable and
readily replaceable. It is permissible to integrate the design of Boat landing and barge
bumper systems into a single unit. Analysis of jacket framing members is carried out for
the boat impact loads on Barge bumper for this purpose the force equal to the rated load
of the shock cell is applied at the shock cell support points. No one-third increase in
permissible stress is allowed in Jacket framing member for this analysis. However, onethird increase is allowed for a vertical member supporting the barge bumpers / shock
cells.
Riser Protector/Conductor Protector: All riser / conductor protectors are designed to
absorb a concentrated impact energy of 100 tonne metres (TM) applied any where on face
at any point. Plastic collapse analysis may be performed for this purpose. Any point on
the deflected structure is at least 300 mm clear from any present or future riser /
conductor. Vertical member is grout filled. The support of the riser / conductor
protector, which are welded to the jacket is designed elastically. No increase in basic
permissible stresses is considered.
Conductor Guide Framing: The support for Curved Conductor is designed for elastic
bending forces in combination with extreme storm design environmental conditions. The
designs of Conductor guide framing also consider the load imposed during and after the
installation of Conductors. As a minimum the following criteria are considered for the
design of Conductor guide framing:
iii. Top Level: Weight of all the Conductors (Straight and Curved) installed in the
substructure prior to drilling of 1.5 time the weight of the Conductor which will
initially pass this level, whichever is applicable.
iv. Second Level: 1.5 times the weight of the Conductor, which will initially pass this
level.
v. Subsequent Level: 0.5 times the weight of the Conductor, which will initially pass
this level
Conductors: Curved Conductor is generally pre-installed in the substructure before the
substructure load out. Curvature of curved conductors is taken 3° per 30.5m of arc
length. The minimum clearance between any two Conductors is not less than 600 mm
below mudline and 150 mm above mudline.
ARCHITECTURAL DESIGN CRITERIA
The Architectural Design Criteria is to specify requirement to size the Building module.
The requirement are stated below:
Æ Occupancy
Æ Type of living room required
Æ Provision of kitchen, dining, frizer, chiller, dry-storage-food lay down area
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Æ Requirement of entertainment room like TV / DVD room, recreation room, games
room, gymnasium room
Æ Infirmary
Æ Provision of number of office, conference room, library, document room
Æ Radio room, battery room, control room, switchgear room
Æ Water heater-HVAC / AHU, chiller
Æ Laboratory
Æ Any other requirement of room varying from project to project.
The safety requirement aspect is also specified in the Architectural Design Criteria like
provision life boat, life raft, fire extinguisher, smoke detector, fire hose reel, dry chemical
fire extinguisher etc. It also specifies the requirement like type of flooring required for
different type of room, wall paneling, false ceiling, requirement of fire integrity of wall
etc.
CLAMP-ON STRUCTURES
In clamp-on structure 3 additional wells for drilling are installed on the existing well
platform. Main and Cellar Decks with well conductor guides are extended towards
north side of existing well platforms by welding structural members. Since welding
below water is difficult, therefore, well conductor guides are attached with a tubular
frame and this frame is fixed to the existing jacket horizontal members with the help of
clamps. Vertical and curved conductors are installed after installation of well conductor
guides. To protect the well conductors, conductor protector is also installed at water
level.
Following codes as followed in platform structure are also followed for establishing
design criteria for clamp-on structure:
API RP 2A
AWS D1.1
AISC, 9th. Edition
DNV RP B401/NACE RP-01-76
Structural Design Philosophy for Clamp-On Structures
The in service design analysis consist of in place analysis which determines the sizes of
structural members. The extreme and operational environmental loads combined with
dead weight and elastic bending forces of curved conductors are analysed for
determination of design loads for each structural member.
Structural analysis and design as followed for platform structure is also followed for
clamp-on structure except analysis for load out, transportation, seismic/earthquake
loads. Since piles are not involved, therefore, pile drivability analysis and grouting are
not done in clamp-on structure.
Basic Load Cases and Load Combinations
Like platform structure basic load cases with contingencies for variation of dead load
with following load combinations are considered for in-place analysis:
Load Combination -1
Dead Load + Live Load + Extreme Storm + Elastic Bending Force
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Load Combination -2
Load Combination -3
Dead Load + Live Load + Operational Storm + Elastic Bending Force
Dead Load + Installation Wave Load + Elastic Bending Force +
Installation Load
Dead Load + Installation Wave Load + Elastic Bending Force +
Installation Load
Dead Load + Installation Wave Load + Elastic Bending Force +
Installation Load
Load Combination -4
Load Combination -5
Conductors for Clamp-On Structures:
Vertical and curved conductors are installed after completion of installation of guides,
main deck and cellar deck installation.
5.7
ELECTRICAL:
The offshore platforms are having their own generating source of electrical power to
meet the requirements of process utilities and other electric drives, living quarters,
platform illumination system, communication and annunciation system, fire and gas
alarm system, etc. The Electrical Design Criteria broadly outlines the minimum
requirements for the design, selection, sizing and installation of the electrical equipment
and associated system on the platform. The philosophy being followed for the above is
described in the following sections.
5.7.1
SALIENT FEATURES OF ELECTRICAL DESIGN PHILOSOPHY:
The electrical system on an offshore platform is designed to provide
Æ Safety to personnel, equipments and marine life
Æ Reliability of service
Æ Minimal fire risk
Æ Ease of maintenance and convenience of operation
Æ Automatic protection of all electrical equipments through selective relaying system
Æ Adequate provisions for future expansion and modification
Æ Maximum interchangeability of equipments
Æ Fail safe features
Æ Hook-up provisions with existing facilities, wherever required
5.7.2
CODES AND STANDARDS:
The specification of design documents, material and system performance is based upon
the requirements of the latest versions of all applicable International Standards, Codes,
Regulations and Code of practice being followed by the Industries world-wide. Some of
them are listed below IEC
NEMA
ASTM
NFPA
IALA
-
International Electro Technical Council
National Electrical Manufactures Association (USA)
American Society for Testing of Material (USA)
National Fire Protection Agency (USA)
International Association of Light House Authority
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BIS
ANSI
API
NEC
RIIS
SOLAS
NESC
DNV
NACE
-
British Standard Institute
American National Standards Institute
American Petroleum Institute (USA)
National Electric Code (USA)
Research Institute of Industrial Safety, Japan
Safety of life at sea
National Electric Safety Code
Det Norske Veritas
National Association of Corrosion Engineers
In the event of conflict between codes being used, the most stringent one is followed.
The electrical design documents are generally drafted on the basis of International
Standards or equivalent Indian Standards. However, Indian Standard is used only
Æ Where required by regulation or Indian law and
Æ Where they are more stringent than international Standards or
Æ Where there is no suitable international Standard
If Indian standards are legally required, but are less stringent than the corresponding
International Standards, the international standard is followed. The definition of most
stringent is that approved by Company.
5.7.3
GENERAL REQUIREMENTS:
Site Conditions
All electrical equipment and accessories / material are suitable for installation and
operation under extremely saline, humid, corrosive and hostile marine environment with
specified degree of hazards.
General Safety
The electrical system employs safety margins to ensure that platform is safe under all
operating conditions, including those associated with the start up and shutdown of
equipment and throughout intervening shutdown periods. The emphasis in equipment
specification is on operability, prevention of accident / fault and functionality for the
intended design life. All insulating materials specified for the equipment are non toxic.
Fire Integrity
All cable penetrations through firewalls, switchgear room walls and between safe and
hazardous area are sealed using multi cable transits to maintain fire integrity and
prevent gas migration.
Evacuation
All services required for safe evacuation of the facility are designed to operate for
sufficient time after loss of both main and emergency power at the platform. The
support duration is in line with the risk assessment study.
Material, workmanship & suitability
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All material used in the construction of electrical equipment, cables, mounting and
fastening devices, etc., are to be of latest specifications, new and in manufacturer’s
current production. Material scheduled for modification are not be used, unless
approved by Company. Should any material proves unsatisfactory it is to be rejected
notwithstanding any previous satisfactory examination on test of similar material or of
equipment.
5.7.4
ELECTRICAL LOADS:
Definitions
The following definitions are applied in the preparation of load schedule.
Brake Power ( KW ) – Power transmitted along the shaft to the mechanical equipment
Nominal power – Name plate rating of motors or load absorbed by non- motor load.
Efficiency ( % ) - As per vendor data
complying with IEC Std
the ratio of output power to input power
Load classifications
Electrical loads are classified as Normal, Emergency or Critical.
Normal
Critical
Emergency
-
Loads in service for full production application
Load required for life support and occupancy purpose
Loads required for personnel safety/safe shutdown and
abandonment purpose
Utilization Category
Load are divided into following three classes according to use.
Continuous load
Intermittent load
Stand-by load
- which draws power at continuous rate
- which draws power as per duty cycle for small time
- which are connected with power supply and ready to act
as and when required.
Load assessment
All Electrical loads are developed by contractor based on estimated load identified in
mechanical equipment list. The data sheet is issued to specify maximum power
requirement. In evaluating load summary, utilisation category is applied as follows Total Load
i) Continuously operating equipment - 100% of operating load
ii) Intermittent load
- 50% of the total intermittent load or the
largest intermittent load whichever
is greater
iii) Stand-by equipment
10% of total ‘standby’ load or largest
stand by load, whichever is greater
iv) Margin for future load growth
10% of estimated load
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The total load shall be sum of i), ii), iii) and iv).
5.7.5
GENERATION AND UTILIZATION VOLTAGE LEVELS:
Generation Voltage
The generation voltage on a process platform is usually 6.6 KV and in some cases 11 KV.
Utilization Voltage ( Nominal )
i) 6.6 / 11 KV AC, 3 Ø, 50 Hz - For motors rated 160 KW and above
ii) 415 V AC, 3 Ø, 50 Hz
- For motors rated at 0.37 KW upto 160 KW,
Battery chargers, UPS, Platform Illumination
system ( Normal Lighting ), HVAC, Bulk AC loads (
like Process heaters ), etc.
iii) 240 V AC, 1 Ø, 50 Hz
- For motors rated below 0.37 KW,
Platform communication system, Radio
Equipment, Anti- condensation space
heaters,Convenience oulets, Level gauge
illumination, etc.
iv)
110 V DC, 2 wire
- Critical lighting, Switchgear & Generator
controls, DC motors for Emergency lub oil
pumps, etc.
v)
24 V DC, 2 wire,
- Instrument supply, Fire & Gas detection
system, CP monitoring panel, etc.
vi)
12 V DC, 2 wire
- Navigational Aids system
vii)
110 V AC, UPS
- Distributed Control System
viii)
240 V AC, UPS
- Telephone Exchange, CCTV system,
Radio system, Paging & Intercom system,
Telemetry, telecom and computer system
5.7.6
CALCULATION METHODS:
Fault levels
As part of detailed engineering, initial fault current calculation is carried out based on
typical vendor data for machines parameter with specified design tolerance. The
calculations identify the maximum expected values of switch gear making and breaking
fault currents, including motor contribution. Calculations are to be done as per IEC
60909. Switch gears are to be designed such that actual fault levels are at least 20% below
the switch gear ratings, considering transient, fault break, fault make and peak fault
levels.
Cable Sizing
During detailed engineering all power and control cables are identified and sized
according to the requirement of Indian and International standards. The sizing
calculation takes into account following factors –
•
•
Connected load
Current carrying capacity
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•
•
•
Voltage drop
Short circuit temperature rise
Laying conditions
Wherever possible, power cables and control cables are to be run separately or with
adequate spacing to minimize the effects of de- rating. Motor cables are generally
selected from a standard 415/600V AC Motor Cable Selection chart. For branch circuits
and feeders, conductor current rating is to be established on the basis of 125% of design
load current at an ambient temperature of 40ºC and de-rated for grouping and method of
installation. Final sub-circuits are sized from standard 240 V AC cables selection charts
based on circuit breaker rating and voltage drop limit.
The voltage rating of cables is as follows –
High Voltage cables
Power & Control cables
Instrumentation cables
DC cables
-
6.6 / 11 KV
600 / 1000 V
250 V
150 V DC
Voltage drop
•
The maximum allowable voltage drop in any feeder under steady state condition
is to be maintained as follows –
Motors
Switch Boards / Distribution
Boards, Lighting / Power Panels
Lighting Points
DC System
•
•
5.7.7
-
3%
-
1%
2%
3%
The voltage drop at the worst affected pre- loaded bus is not to be exceeded 15%
of nominal voltage during start –up of the largest motor.
The voltage available at motor terminals during start- up is to be sufficient to
ensure positive starting and acceleration to full speed by the
motor
(
even in motor fully loaded condition, if required ) without causing any damage
to the motor. However, under no circumstances, the voltage at motor terminals
during starting is allowed to fall below 80% of the nominal voltage.
SPECIFIC REQUIREMENTS FOR EQUIPMENT & ASSOCIATED COMPONENTS:
Environment
Electrical equipment, installation material, wiring and cabling etc. are suitable for overall
climatic condition, their position within the installation and the local environment. The
conditions are likely to encompass exposure to moisture and salt laden atmosphere, sea
spray, sunlight, extremes of temperature and humidity, fungal growth, abnormal
vibration and shock.
In general, all outdoor electrical equipment are to be designed for 40°C temperature and
maximum 90%RH while the indoor equipment are to be designed for 45°C temperature
and maximum relative humidity of 90%.
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Corrosion
For out door locations, corrosion resistant material are considered
for electrical
equipment. As a minimum material / equipment requirements are as follows –
Cable ladders and trays are fiberglass reinforced plastic and UV protected.
Associated accessories are SS -316.
Explosion- proof junction boxes, light fittings,
control stations, etc., are to be
manufactured from cast stainless steel or copper -free aluminum with an epoxy finish.
ƒ Cable glands are nickel plated brass or equivalent.
ƒ
ƒ
ƒ
Proof of material suitability is required to ensure that the chosen material is suitable for
the intended design life of the equipment/ facility.
Degree of Protection
The degree of protection against dust and water ingress, necessary for individual
electrical items is determined by the equipment duty, its environment, its location and
the hazardous area classification. The equipment located outside or subject to deluge
from fire water system are to be specified weather proof construction and protected
against the most adverse conditions that are anticipated. These enclosures are to be
classified to IP-56 as a minimum degree of protection, increased as necessary where the
location/situation demands. Indoor equipment will be a minimum of IP-42 protection
and accessible equipment within enclosures will be a minimum of IP-22 degree of
protection. Where indoor has specific ventilation requirements lower ingress protection
rating will be considered subject to evaluation.
Hazardous area Requirements
The hazardous area classification is carried out in accordance with API-RP-500.The
hazardous area classification drawings form the basis for layout of electrical equipment
for various locations. All equipment selected for use in hazardous areas are to be certified
by internationally recognized certification agency.
Equipment shall have certification of CENELEC, BASEEFA, UL or FM or equivalent
international testing agency for the area and service in which they could be used. All
outdoor electrical equipment on the platform handling oil and gas are , at least, suitable
for Class -I , Division - II , Gas Group - D area unless otherwise specified. However,
equipment / items installed in battery room are suitable for Class –I, Division -1, Gas
Group - B area.
Lighting
Normal lighting circuits are rated at 230 V, 50 Hz AC supply. The power for lighting is
made available through a lighting transformer installed in switch gear room and is fed
from 3 phase ,440 V , 50 Hz feeder coming from emergency switch board. Lighting
system has provision of dimmerstste to vary the illumination level from zero to 100%.
Normal lighting fixtures normally constitute 70 % of total luminaires and remaining 30
% fixtures are of emergency lighting. The external area of platform are fitted with
fluorescent luminaires rated for Class -I, Div.-I hazardous area and have an ingress
protection of not less than IP -56. Out door emergency lighting
fixtures are self
contained battery / inverter fluorescent lighting fixtures having duration of 90 minutes
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and are to be certified for Class – I, Division - I hazardous area. The temporary escape
emergency lighting fixtures are strategically located along stairways and walkways,
escape routes, switch gear room, battery rooms and boat landing area to provide
adequate illumination for personnel to evacuate in the event of emergency.
Emergency light fittings are designed in accordance with IEC60598 -2-22, thus the
specified battery autonomy of 90 minutes must be met after 4 years of continuous
operation. Battery for Navigational Aids have autonomy time of 7 days which is to be
met after 25 years of operation.
Exit lighting fixtures are provided on each door of equipment housing. Flood lights are
provided where illumination for large and open area is required, such as the main deck,
boat landing, etc. All light fittings are to be secured and fastened using SS - 316 fasteners
and accessories.The highest point on the platform is fitted with omni directional red
obstruction light. The required maintenance intervals for all light fittings in continuous
operation are not to be less than 3- 4 years.
Transformer for Normal Lighting.
Two nos. of lighting transformers are normally provided in switch gear room. Each
transformer is sized for 120% of the predicted distribution design load so that either
transformer can supply 100% of load. The transformer is to be sized , using natural air
cooling with the ambient condition of switch gear room.
The transformers are natural air cooled , cast epoxy resin dry type , suitable for indoor
installation. For stepless variation of lighting voltage, the motorised controlled
dimmerstate are to be provided to vary the illumination level of lighting system
Switchgears
Feeders for 400 ampere rating or more are provided with ACB. Feeders for more than 63
ampere rating and up to 400 ampere rating have MCCB. Feeders of up to 63 ampere
rating have MCB. However, all motor feeders have MCCBs regardless of ampere rating.
Bus bar and isolating devices are rated at 125% of design load. Bus bars are generally
identified as R, Y & B with phase coloured as red, yellow and blue. All the switch gears
are industrial grade equipment installed in free standing sheet metal
cubicles of
modular design. All the switch gears are to be installed in a closed naturally ventilated
room .
Air Circuit Breaker ACB
Incomer feeders are withdrawable air break type with charging motor , spring release
and close mechanism. Breaker close /trip solenoid are fed through 110 Volt DC .
Motor Starters / Contactor feeders, MCCB / MCB Feeders
Each starter unit have component designed for Type- 2 co-ordination as per IEC.
Switchboard and MCC have front access and the switch gear and starter components are
‘withdrawable’ type as per IEC - 60947 . Compartments are capable of withdrawing to
a test position. This test position isolates the motor power cables to allow the live
commissioning of control circuit. The LV switch boards are provided with a minimum
of 20 % fitted spare motor starters and feeder modules.
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Motor starters invariably have MCCB for short circuit protection regardless of ampere
rating.
Protection Equipment
The equipment defined
provides adequate safeguards against the effect of any fault
occurring on the system or component parts. All protective devices , including relays and
current transformers ( CTs ) etc. are to be adequately rated to withstand the prospective
short circuit current, which can flow or be induced. Where ever applicable, unrestricted
over current relays provided have IDMT characteristics of the standardised type.
Where ever applicable, the relay protection devices are such that a clear indication is
given of fault which caused a trip. Circuit breakers are not able to re-close without first
resetting the appropriate master trip relay.
Motor Protection
Contactor units used as
protective devices –
•
•
•
•
LV ( 600 volt)
motor starters
incorporate the following
MCCB for Short circuit.
Single phasing prevention relay for motors.
Earth fault protection for motors above 37.5 kw.
Overload relay.
AC Incomer & Outgoing Feeder Protection
ACBs used for 600 V Incomer & Outgoing feeders are to be provided with short circuit
and overload protection, as minimum.
DC Feeders ( 110V DC, 24V DC, 12 V ) Protection
MCBBs / MCBs used for DC incomer feeders and DC distribution feeders are to be
provided with short circuit and overload protection, as a minimum.
Transformer Protection
As a minimum the following protection shall be provided for transformers over current
with instantaneous trip.
Back up Protection
Time and time- current grading of up stream protective devices provide back up
protection. There are no specific back up protection for failure of primary protection to
clear faults. The design features are such as to clear a fault in a total clearance time of 0.5
seconds if the primary protection fails to clear a fault for any reason.
Bus tie Protection
There are no special protection and tie-breaker acts like a switching device.
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Socket outlets
Socket outlet are provided on the platform as 415 V, ,50 Hz, 3 wire plus earth 63 amp, 4
pin and 240 V, 50 Hz, 2 wire plus earth , 15 A, 3 pin certified for use in Class - I Division I. Sufficient socket outlets are specified to enable normal operation, maintenance, testing
and inspection of installation. Socket outlets are provided with earth leakage protection,
30 mA for 240 V, outlets and 300 mA for 415 V, welding outlets via dedicated distribution
board.
Junction Boxes
Junction boxes for use in outdoors are to be certified for use in Class – I, Division - I,
Hazardous area and fabricated from the following material - SS –316, Epoxy coated
copper- free aluminum suitable for 25 years of service life.
MOTOR START / STOP CONTROL STATION ( PUSH BUTTON STATIONS )
The push button stations are suitable for Class - I, Division - I hazardous area. They are to
be fabricated from copper- free aluminum alloy. The cable entry glands are nickel plated
brass material and of double compression type with EX(d) protection.
ELECTRIC MOTORS.
All the motors required by mechanical packages ( excepting those for Main Injection
Pump, Sea Water Lift Pump, Booster Pump, wherever applicable ) are designed for 415
V, 3 phase, 50 Hz. and meet the requirement of relevant international standards. Also,
all electric motors meet the requirements for the hazardous area classification indicated
on the respective data sheets.
All motors are totally enclosed fan cooled (TEFC) type with Class - F insulation,
temperature rise limited to class - B. All hazardous area motors are suitable for Class I, Division -I , Temperature Class T-3 and Gas group - D hazards. Hazardous area
protection technique is Ex(d). Any motor rated at 75 kw or above, are fitted with
positive temperature co -efficient thermistors. Motors rated 3.7 KW or above are to be
fitted with anti- condensation space heaters.
Motors for large equipment such as Main Water Injection Pump, Fuel Gas Compressor,
etc., if installed on the platform, are normally provided with variable frequency drive (
VFD starters ) in order to limit the stating inrush current, transient torques and starting
step load on supply source i.e. Turbine Generator.
All motors, as a minimum , are designed to have power rating at least equal to 110% of
the maximum shaft demand of the driven equipment for any of the specified operating
conditions.
NAVIGATIONAL AIDS
The navigational aids along with associated DC supply and battery is to be provided on
the platform.
CABLES
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Cable are heat and oil resistant, flame retardant (HOFR) type suitable for service in
environmental conditions described for the platform. All ( normal and emergency )
cables have flame retardant characteristics to IEC 60332-3 category A. Cables for DC
system including critical lighting system, navigational aids, etc.,are to be fire resistant
type to the requirement of IEC 60331. Cable joints via cast resin kit or other type are not
permitted on the offshore installations.
Special care is taken to the routing and separation of cables to minimize the effect of fire
on emergency and essential supplies and production operations.
All cables are identified with SS - 316 Tags.
In addition the minimum distance between power/control wiring and electronic signal
wiring on prolonged cable route will be as follows –
Power / Control cable
Minimum distance from electronic/ signal cable
Up to 125 V
Up to 300 V
Up to 1000 V
Above 1000V
150mm
150mm
300mm
450mm
Earth Conductor
Earth cable has 6 mm2, 16 mm2 , 70 mm2 or 240 mm2 stranded copper conductor with
CSP or EVA insulated and green / yellow insulation sheath.
Cable support System
The cable system comprises cable installed on cable tray or ladder with 25% spare
capacity for future extension. Intrinsically safe circuit cables run in separate trays. Cable
straps or ties are SS - 316.
Cable tray /Ladder
Two primary cable tray / ladder system are installed on the platform.
Æ Low voltage power and control cable ( normal and emergency )
Æ Instrumentation, control and ESD.
The cable trays / ladders are heavy duty type capable of being loaded to 120 Kg/m with
6 m support spans to NEMA 20B. Cable ladders /trays are to be manufactured from
FRP material with UV protection features.
Cable ladders are fitted with removable , ventilated covers where there is exposure to
chemical spillage, falling object or direct sunlight. The covers are suitable for cyclone /
monsoon conditions.
Cable trays are installed in accordance with manufacturer’s recommendations and
specifically supported at each elbow. The overhead cable trays are installed a minimum
of 2.5 meter above deck.
Cable Glands and Multi CableTransit ( MCT ) Frames
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Suitable size double compression type glands are supplied for all cables. For entries into
Ex(d) enclosures, barrier type ( or compound filled) gland are provided. All cable glands
and adaptors are made up of nickel plated brass and are fitted with soft sealing nylon
washer. Fibre washers are not to be used.Lock nuts are used for entry into sheet steel
boxes enclosures.
Industrial cable glands are not used on offshore platforms. All cable glands are to be
type tested and certified for use in specified hazardous area.
Cable transit frames are to be fitted where cables pass through Æ Decks and walls to open air,
Æ Fire walls,
Æ From safe to hazardous area.
Such cable transit frames are designed to include 25% spare capacity for future use.
Cable transit frames are to be supplied with test certificates from an accredited
independent test authority to confirm a fire rating adequate for deck or wall in which
they are to be installed.
Cathodic Protection
Cathodic Protection for Rigid Structures and Submarine Pipelines is to be carried out in
accordance with respective Equipment specifications.
5.7.8
ELECTRICAL EQUIPMENT/PRODUCT / MATERIAL SELECTION PHILOSOPHY:
All electrical equipment / product / material ( viz. motors, transformers, switch gears,
distribution system, cables etc.) offered by the vendor are to be as per relevant
standards, specifications, new and unused, of current manufacture and the highest
grade and quality available for the required service, and free of defects. The equipment is
to be protected from construction damage and damage in transportation. and damage
due to sandblasting and painting.
The selection of electrical equipment / product / material is generally based on the
following factors Æ Functional specifications and electrical design criteria in respect of each
individual equipment
Æ Applicable Standards , Codes & Recommended Practice
Æ Reliable & trouble free performance for 25 years of design life
Æ Safety
Æ General Operating / Site conditions
Æ Hazardous area classification
Æ Suitability for the specified requirement for use in outside pressurised rooms
and inside pressurised rooms
Æ Suitability for the corrosive effects of the saline and humid marine atmosphere,
galvanic action, etc.
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5.7.9
VENDOR PRE-QUALIFICATION:
All offered electrical product or equipment or equipment with similar designs and
construction features, manufactured by the same vendor -
5.7.10
•
Shall have been type tested by an authority approved by ONGC
•
Shall have been in continuous satisfactory service on offshore installation for a
minimum period of two ( 2 ) years and should be under manufacture at least for
the last three ( 3 ) years, unless otherwise specified
•
Shall have a current certification /approval /listing by UL or FM or by an
agency approved by ONGC.
ELECTRICAL EQUIPMENT CALCULATIONS:
Certified calculations, as listed below, for electrical equipments of process platform in
respect of size / rating / power / capacity, etc., are to be provided by the contractor for
approval of ONGC during Detailed Engineering –
Æ Turbine Generators
Æ Transformers
Æ Electric Motors
Æ Switch gear and control gear
Æ Power and control cable
Æ MCTs
Æ Area lighting fixtures
Æ Cable trays
Æ Battery & Battery Chargers for various system
Æ Earthing cable/conductor
Æ Lighting transformer
Æ Cathodic protection system
These calculations form part of the relevant Purchase Specification to be submitted
during detailed engineering.
5.7.11
REVIEW AND APPROVAL:
All Purchase Specifications along with list of deviations, calculation sheets, offers of the
vendor and all relevant documents are to be furnished for ONGC’s approval during
detailed engineering. Contractor is advised not to place order for purchase of any item
without obtaining prior approval from ONGC in writing.
Contractor prepares and furnishes the list of all drawings / documents enlisted in the
bid document for ONGC’s review. The category of drawings / documents ( i.e. whether
to be reviewed / approved by ONGC is generally decided in consultation with
contractor and ONGC’s consultant after award of Contract.
All vendors drawing are to be submitted for ONGC’s, review after the contractor’s
engineering consultant approves them.
5.7.12
TAGGING AND NAMEPLATES:
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All equipment ( Motors, push buttons, motor control centers , push button stations, pull
boxes etc. ) are provided with SS tag or nameplate of a permanent type with
identification number and service description.
The Contractor assigns individual tag numbers in accordance with ONGC’s established
system to all electrical equipment. The tag number that pertains to a electrical
equipment appears invariably on all drawings and documents.
Nameplates and identification tags are to
equipment and / or their component.
be
provided to properly identify each
All panel electrical equipment nameplates are to be made up of white laminated plastic
plates with black engraved lettering and securely fastened with SS -316 screws.
All front panel mounted equipment are to be identified with a metal or plastic nameplate
attached to the rear of the device and easily visible via the rear access doors.
All wiring, power and control cables, junction boxes and auxiliary equipment are to be
suitably identified as per applicable codes and practices. Plastic adhesive tapes are not
used for identification. All wirings are to be tagged with slip- on or clip-on wire marker
at both ends with the wire number specified on the drawing.
5.7.13
ELECTRICAL EQUIPMENT INSPECTION & TESTING PHILOSOPHY:
The Contractor’s quality plan includes a comprehensive fully documented inspection
and testing plan specific to the project and it is to be submitted to ONGC for review and
approval. The inspection procedures includes inspection specifically for compliance
with hazardous areas requirements.The Contractor is also required to provide suitable
workshop, equipment and all necessary tests for electrical equipment.
ONGC reserves the right to reject any or all test work, if found unsatisfactory / not upto
the mark.
In addition to yard testing of loop checking and setting for safety devices like overload
relays etc. and simulation testing of all interlock and shutdown systems,they are required
to be carried out in offshore also.
Insulation tests are to be carried out on all cabling by using a megger of 500 volt DC.
The IR value is required to be more than 10 M ohm for acceptance.
Correct connections of all electric equipment are to be checked.
All testing and pre-commissioning activities are required to be done by the Contractor.
The Contractor is also required to provide assistance for ONGC’s commissioning
activities.
The Contractor is required to provide written results of all above tests, if so required by
ONGC. Also, the contractor is required to furnish reasonable evidence of the satisfactory
condition of test equipments.
5.7.14
ELECTRICAL EQUIPMENT SPARES PHILOSOPHY:
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For all major equipment, the Contractor is required to include normal commissioning
spares as a part of the equipment. The Contractor is also required to furnish separately,
list of recommended spares for two year’s trouble free operation along with the prices for
purchaser’s review.
The spares requirement of individual systems shall be as per the relevant functional
specification.
5.7.15
TRANSPORT AND SHIPMENT:
All electrical equipment, cables and trays etc. are required to be securely anchored to the
skid. All equipments that could be damaged in shipment shall be removed, tagged and
crated in a weatherproof box. Weather proof box shall protect the equipment from
dynamic forces.
All openings, flange thread connections and cables exposed as a result of cable removal
are required to be protected in a manner to prevent damage during shipment.
5.7.16
WARRANTY:
Contractor is required to warrant that his equipments will satisfy the requirement of
intended use and it is free from latent defect.
The contractor is also required to assume responsibility for obtaining manufacturer’s
performance warranty for all equipment purchased by him. Contractor will then assume
this warranty in his guarantee to the company.
Contractor is required to agree to repair or replace any equipment which proves to
defective within 12 months after being placed in operation but not exceeding 18 months
from date of shipment.
5.8
PIPELINE:
5.8.1
DESIGN PARAMETERS:
Design Life: 25 Years
(a) Rigid Pipelines:
The design of pipelines, risers, tie-ins, pipeline crossings and free span corrections
follows the guidelines of Det Norske Veritas Rules for submarine pipeline system
1981 (DNV). The design and loading conditions and design criteria are as defined in
Section 3 & 4 of the above rules. Constants and coefficients to be used for the design
calculations are taken from these rules except as specified below:
i)
Maximum allowable steel
stresses during installation.
loading condition “b” (SMYSSpecified Minimum Yield Strength).
During Hydrotest:
:
85% SMYS
:
90% SMYS
ii) Zone-1
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Maximum allowable steel
stress during operation
Pipeline, load condition 'a'
Pipeline, load condition 'b'
iii) Zone-2 (upto a distance of
12.2M from bottom end of
the riser bend)
Load Condition 'a'
Load Condition 'b'
:
:
72% SMYS
85% SMYS
: 50% SMYS
: 67% SMYS
Von Mises Stress Hypothesis
is to be used for determination
of combined stresses in the
riser/pipeline
(b) Flexible Pipelines
The design of flexible pipelines and riser system, pipeline crossing, and tie-ins shall
follow the guidelines of API RP 17B “Recommended practice for Flexible Pipe” and
Specification for flexible pipe material as per Spec. 2020E Rev. 2.
Flexible pipeline is to be designed for hydrostatic collapse for a breached outer
sheath with the pipeline in empty condition. The different layers & sub layers in
each layer and thickness of layers required in the structure is finalized during
detailed engineering.
Environmental Parameters are defined on the basis of Glenn’s Report.
Pipeline sizes, design temperature/pressure, material (for rigid pipeline) etc. are decided
after basic engineering.
The geotechnical data is collected during pre engineering survey as per Spec. 2011 Rev. 1.
The soil data collected should be enough to determine strength and index properties
required for engineering, areas prone to scour and instability.
5.8.2
APPLICABLE CODES AND STANDARDS:
DNV 1981
ANSI B31.4
IP Part 6
ANSI B31.8
API Std.1104
API RP 1110
API RP 1111
-
United States
-
SIS 05-5900
-
Rules for Submarine Pipeline System(For rigid pipelines)
Liquid Petroleum Transportation Piping Systems.
Institute of Petroleum, Model code of safe Practice.
Gas Transmission and Distribution Piping Systems.
Standard for Welding Pipelines and Related Facilities.
RP for the Pressure Testing of Liquid Petroleum Lines.
Recommended practice for design, construction, operation and
maintenance of offshore hydrocarbon pipeline.
Minimum Federal Safety Standards for Gas Lines.
Part 191,192
Minimum Federal Safety Standards for Liquid Pipelines.
Part 195
Swedish Standards Institution for Surface Preparation.
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5.8.3
DNV RPB-401
NACE RP-06-75
-
API RP 5L1
-
API RP 2A
-
API RP 5L5
DNV OS-F101
API RP 17B
DNV TNA 503
-
Cathodic Protection System
Recommended Practices: Control of Corrosion on Offshore Steel
Pipelines.
Recommended practice for Rail – Road Transportation of Line
pipe.
Recommended practice for planning, designing, construction of
fixed offshore platforms.
Recommended practice for marine transportation of line pipe.
Submarine pipeline systems
Recommended Practice for Flexible Pipe
Technical notes for flexible pipes and hoses for submarine
pipelines system.
STABILITY ANALYSIS:
The stability requirement is evaluated by lateral and vertical stability analysis of the
pipeline during installation, testing and operation. The lateral stability analysis includes
all environmental forces such as drag, inertia and lift as well as frictional resistance. The
vertical stability analysis includes pipe buoyancy, an assessment of soil liquefaction
potential, trenching depth and backfill material requirements. The following design cases
are considered:
-
Pipe resting on the seabed
Pipe in a Trench (if applicable)
Pipe resting on seabed and stabilized by other means such as placing additional
restraints e.g. grout bags, blocks, etc.
Pipe crossing with pipe resting on supports.
The stability requirement is primarily met by increasing the submerged weight of the
pipe.
The required submerged weight of the pipe for the stability analysis is determined for the
following design conditions:
5.8.4
Pipe empty during installation
Pipe filled with product during operation.
STRESS ANALYSIS AND UNSUPPORTED SPAN:
The criterion for pipe stress analysis is to maintain all stresses during installation, testing
and operation within the allowable limits set by Section 1.0.
To keep pipeline stresses within the allowable limits, the unsupported spans shall not
exceed certain maximum values. The static allowable spans are calculated for the
following three pipeline conditions:
Æ Pipe empty after installation
Æ Pipe flooded during hydrostatic testing
Æ Pipe filled with product during operation.
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In addition, the pipeline is designed to avoid excessive vibrations due to vortex shedding
by limiting span lengths so that resonance does not occur. If this is not feasible, safety
against fatigue failure is analyzed.
For each of the three pipeline conditions mentioned above the shortest calculated span
length is used as the maximum allowable span length.
5.8.5
COLLAPSE AND BUCKLING ANALYSIS:
Wall thickness is checked against collapse in addition to hoop stress.
Local buckling due to external over pressure, bending and propagation buckling due to
external over-pressure are also analyzed.
5.8.6
CORROSION PROTECTION:
Pipeline external corrosion protection is provided by corrosion protection coating. This
coating shall be a double coat and wrap as per the specification 2012 Rev. 1 for rigid
pipelines.
5.8.7
CATHODIC PROTECTION:
The cathodic protection of pipelines is provided in accordance with the Specification No.
FS 4020B Rev 0.
5.8.8
ROUTE AND PROFILE:
Utilizing the survey information the pipeline alignment is finalized. The pipeline route
shall be selected such that the pipeline follows a smooth seabed profile, and avoid,
wherever possible, coral reefs, and soft or liquefied soils. Where it is not practical to
avoid seabed irregularities, capable of causing significant stresses in the pipeline, stress
levels shall be checked against the allowable stresses. In the event that the stress levels
exceed the allowable limit, the pipeline profile shall be modified such that the stress
levels are within the allowable limits. Unsupported pipeline spans shall not exceed the
allowable limits calculated.
5.8.9
OFFSHORE PIPELINE CROSSINGS:
The crossings is designed, such that the existing or proposed pipeline shall not be overstressed, either during installation or operation, according to criteria mentioned in
Section 1.0 and the resulting spans shall not exceed their allowable limits.
The stability analysis of the pipeline and supports at the crossing is based on maximum
wave heights/significant wave height at operating conditions.
Separators are provided to maintain physical separation of 350mm or more between the
existing pipeline and the proposed pipeline for the life span of the proposed pipeline.
5.8.10
PIPELAY ANALYSIS:
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The laying analysis is performed using the details of the proposed barge/laying method
to confirm that pipelines can be laid with proposed barge and the design thickness
without exceeding allowable stresses.
5.8.11
RISER DESIGN:
The design of riser is carried out in compliance with the requirements of Section 5.8.1 and
code & standards specified in Section 5.8.2 above.
5.8.11.1 Riser Location:
Riser location is finalized after pre-engineering riser face survey during detail
engineering. Flexible pipeline riser is enclosed in I Tube/ J Tube.
5.8.11.2 Stress Control (Rigid Pipelines):
The criterion for the riser stress analysis is to provide a safe and functional riser design.
Stresses during installation, operation and testing shall not exceed the allowable limits as
per Section 1.0. Expansion of pipelines and movement of jacket due to operational and
environmental load is also to be considered in the riser design.
For stress analysis of riser, the temperature decay along the pipeline is to be considered
for thermal expansion of the pipeline.
It shall be endeavored to absorb in the riser any expansion/contraction in the pipeline or
deflection of the platform caused by environmental and functional forces without the use
of expansion loop by locating the first riser clamp as high as possible from the seabed or
increasing the submerged weight of the pipe-line near the riser end, thus ensuring that
the stresses in the riser are below the allowable limits and the loads transferred from the
risers to the jacket are minimized. Flexibility analysis of the riser is carried out.
5.8.11.3 Clamps and Location:
Riser is supported by hanger flange and Riser (in case of rigid pipelines)/ I Tube- J Tube
(in case of flexible pipelines) is guided by non-frictional riser clamps attached to the
platform.
The clamp spacing shall be such that the risers are safely supported and that calculated
allowable spans are not exceeded. Number of clamps and their location shall be selected
to prevent the riser from becoming over-stressed during design storm conditions while
the pipeline remains in full operation. Spacing of riser clamps shall be based on risers
withstanding storm conditions, temperature stresses and vortex shedding criteria given
in Appendix-A to DNV rules for submarine pipeline system. Clamps shall be internally
padded with 12mm thick neoprene bonded to the clamps steel surface by adhesion.
Where adjustable clamps are provided, electrical continuity for cathodic protection of
clamps shall be provided between jacket and clamps. All bolting on the riser clamps shall
utilize fully tightened double nuts on each end of the struts. All nuts and bolts used for
clamping the risers shall be XYLAN coated.
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5.8.11.4 Coating of Risers and Bends (Rigid Pipelines):
All risers, including bends, are to be coated and wrapped with the corrosion protective
coating as described in the specification attached, from the sea bed upto the splash zone.
All risers are to be coated with a concrete weight coating upto splash zone. The minimum
thickness of concrete coating on risers shall be 30 mm. The field joint coating at the riser
to pipeline connection and on risers shall follow the guidelines set for pipeline field
joints.
Risers extending above the splash zone are to be painted in accordance with general
specification 2005 Rev.0 "Protective Coating".
"Monel Jacket" is to be applied on portion extending from (-) 2.0m w.r.t. Chart Datum
upto hanger flange or upto splash zone whichever is higher. A 5mm thick Monel sheet is
to be welded to the riser pipe at top and bottom to form a tight jacket, which should have
facilities for future testing for tightness. At onshore yard, the Monel jacket is checked for
tightness by an air pressure test to 1.5 kg/cm2.
Monel Sheathing shall meet the requirements of Clause 8.13 of Spec. No. 2015 Rev.1. All
the welds shall be coated with epoxy/resin to prevent corrosion.
5.8.11.5 Riser Bend:
Prefabricated shop pipe bends as described in the specification no. 2017 are to be used at
the bottom (only in case of rigid pipelines) and at the top of risers. Bends radius shall be
at least 5 times the outside diameter of pipe and should be suitable for pigging with a
fault detection/intelligent pig.
Transition from one pipe wall thickness to another shall be by internal bevel not
exceeding 1 to 4 taper.
Diagonal bracing shall be attached to the bottom riser bends by clamps during
fabrication. These bracing shall be removed or a 600 mm section cut out of the brace after
riser installation is completed and clamps are tightened. The brace shall not be welded to
the pipeline. The clamps shall be padded with 12 mm thick neoprene padding as per
Clause 8.10 of specification No. 2015 Rev.1.
5.8.11.6 Cathodic Protection of Risers:
Cathodic protection of risers is to be provided in conformance to Spec. No. FS 4020B
Rev.0 and Electrical design criteria.
5.8.11.7 Hanger Flanges:
All pipelines shall be provided with suitable hanger flanges for supporting the risers. The
riser hanger flanges shall be designed, manufactured and installed as per relevant Codes
and Standards.
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Flexibility analysis for all risers and connected deck piping is carried out to determine the
design loads.
5.8.11.8 I-Tubes/J-Tubes (in case of Flexible Pipelines):
I-Tubes/J-Tube along with other related appurtenances like bell mouth/seals, clamp
etc. is designed for all flexible risers. In case of alternative arrangement also, the same
shall be applicable.
The I-tube/J-tube assembly is designed as per structural design criteria and provided
with external Monel sheathing in the splash zone portion i.e. between elevation – 2.0
m and upto the bottom of hanger clamp or +5.5 m elevation, whichever is higher as
per Spec. No. 2015, Rev. 1.
5.8.12
DESIGN REVIEW:
Following reports are prepared during detail engineering:
Æ Pipeline Design Criteria Report
Æ Pipeline Design Report
Æ Riser Design Report
Æ Installation/Testing Method Report
Æ Specifications
Æ Cathodic Protection System design report
a)
Pipeline Design Criteria Report includes:
Æ Appraisal of Data (environmental, bathymetry, soils, etc.)
Æ Selection of the Pipeline Route and pipeline length
Æ Pre-engineering, pre-construction and post-installation survey reports
b)
The Pipeline Design Report includes:
Æ Pipeline wall thickness analysis
Æ Pipeline Stability Analysis
Æ Pipeline Stress Analysis.
Æ Pipe lay analysis
Æ Pipeline Buckle & Collapse Analysis
Æ Pipeline Unsupported Span Analysis
Æ Pipeline Crossing Stability and Stress Analysis
Æ Pipeline Expansion analysis.
Æ Pipe Cathodic Protection Analysis
c)
The Riser Design report includes:
Æ Riser Flexibility Analysis (in case of rigid pipelines)
Æ Riser Stress Analysis (in case of rigid pipelines)
Æ Clamp Loads
Æ Vortex shedding analysis
Æ Clamps and clamps spacing/allowable spans
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d)
The Installation Methods Report shall include :
Æ Pipeline
Æ Risers
Æ Hydrotest
Æ Pull-in Analysis (in case of flexible pipelines)
e)
Specification for:
Rigid Pipelines
Æ Pipe
Æ Pipe Bends
Æ Pipe Fittings & Flanges, if any
Æ Corrosion Protection Coating
Æ Concrete weight coating
Æ Field Joint Coating
Æ Splash Zone Materials
Æ Pipeline Crossings
Æ Tie-in fittings
Æ Cathodic Protection System
Æ Trenching and burial, if required
Flexible pipelines
Æ Pipelines, End Connectors/ Fittings
Æ Corrosion Protection Coating for I-tube/J-tube assembly, end connector/
fittings
Æ Cathodic Protection of flexible pipe, I-tube/J-tube assembly, end
connectors/fittings
Æ Splash Zone Materials
Æ Pipeline Crossings
Æ Trenching and burial, if required
5.8.13
DRAWINGS:
The following drawings are prepared during detail engineering:
Æ Area Maps
Æ Pipeline Alignment Drawings
Æ Anode Installation drawings
Æ Pipeline Approach to and Departure from platforms
Æ Pipeline Crossings.
Æ Riser Elevation and Clamps spacing, riser makeup
Æ Clamps details
5.8.14
PIPELINE INSTALLATION:
All works related to pipeline installation is performed in accordance with the
specifications 2015 Rev. 1 and 2015A Rev. 1. Both, S-lay or Reel-lay methods for laying of
rigid pipelines are acceptable based on overall cost economics.
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In S Lay method the pipeline is tensioned at the lay barge and supported on stinger
having a positive buoyancy to compensate for the weight of the pipeline so as to avoid
generation of higher stresses in the over bend and sag bend region. The following laying
parameters are obtained through stress analysis:
Æ Tension in the pipeline
Æ Length, shape and buoyancy of stinger
In REEL LAY method the pipes are welded together at the shore based yard. Also,
corrosion coating has is applied at the onshore yard. Next, welded pipes are spooled on
to the pipe laying vessel’s reel (normally a D.P. vessel).
To initiate pipe lay, the end of pipe stalk is anchored, and the pipe laying vessel then
move along the pipeline route, unreeling pipes as it advance. In this method, concrete
weight coating cannot be applied, and hence on bottom stability may be achieved by
increasing the wall thickness of the pipe, if required.
For submarine pipeline to be laid by Reel Lay Method, pipe material & procedures, etc.
shall comply to the requirements of Section 7H of DNV OS-F101 Offshore Standard for
Submarine Pipeline Systems 2000 edition.
5.8.15
HYDROSTATIC TESTING OF PIPELINE SYSTEM:
Testing of pipeline & riser system is carried out as per the specification no. 2022 Rev. 0
completion of all installation works of pipelines, risers, crossing, operations and remedial
works, if any. Before hydrostatic testing, the pipeline & riser shall be cleaned with a
mechanical pig. Hydrostatic test is carried out for a minimum continuous period of 24
hours after stabilization, to a test pressure of 1.25 times the design pressure.
5.8.16
POST – CONSTRUCTION SURVEY:
Survey of the installed pipeline system, with all necessary equipment, such as subbottom profiler, side scan sonar, echo sounder etc. for determining the extent of
unsupported spans, damage etc. is carried out.
5.8.17
AS BUILT PIPELINE SYSTEM REPORT:
On completion of hydrostatic testing, As built Drawings/Reports for all pipeline system
is prepared. Alignment details shall be obtained from plotted data taken during
construction and post-construction surveys. All pertinent data such as pipeline
appurtenances, fittings, crossings, unsupported spans, burial details, location of anodes,
elevation of riser clamps, Monel sheath and hanger flange etc. are accurately located on
the "As Built Drawings".
6.0
ISO GUIDELINES FOR BID PACKAGE PREPARATION:
Preparation of the bid package during the basic engineering of a project is done in line
with approved ISO procedures and the documents are prepared as per approved ISO
formats. These procedures and formats form a part of the ISO Manual issued by the
Offshore Design Section.
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The ISO Manual provides guidelines that would enable the Offshore Design Section to
provide services at par with international standards of excellence to the satisfaction of the
customers in the area of Design and Development of offshore facilities. The ISO Manual
consists of three broad sections:
•
•
•
Quality Manual
Quality Procedure Manual
Formats
The Quality Manual defines the policy and objectives of the Offshore Design Section;
resources available with the section and the functional policies of the section.
The Quality Procedure Manual defines the various procedures for different activities of
the Offshore Design Section. The Procedure Manual also identifies the person
responsible for execution of a particular procedure.
The Formats section of the ISO Manual contains forms and checklists used by the
Offshore Design Section. The documents that form a part of the bid package are
generally prepared as per format no.: ODS / SOF / 004 of the ISO Manual.
It is essential to have a good understanding of the requirements listed in the ISO Manual
and prepare the bid package in line with the laid procedures and in the approved
formats, so as to generate a quality bid package that would ensure successful
development of the offshore field and efficient operation of the facility, while
maintaining safety of platform and personnel.
7.0
QUALITY ASSURANCE:
As mentioned in its Quality Manual, the Offshore Design Section is committed to provide
services at par with international standards of excellence to the satisfaction of the
customer. This is ensured not only by generating comprehensive design documents, but
also by ensuring that the products / instruments received are of good quality and can
perform the intended function, while remaining functional for the laid down design life.
This is in turn ensured by accepting products only from established suppliers and laying
stringent inspection and testing requirements for all items / equipments.
7.1
The items / equipment used in the setting up of offshore facilities are always procured
from established suppliers through the turn-key contractor executing the project. In case,
an item is to be procured from a new supplier, the supplier and his product is approved
only after the required pre-qualification documents are submitted and found satisfactory.
These pre-qualification documents include:
•
Past track record of similar item for similar service in offshore application along
with details of clients, type of product, make, size, service, year of completion,
and copies of any feedback information received from clients regarding
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•
•
•
•
7.2
functioning of equipment / material supplied. This is necessary to ensure that
the product offered is not a prototype. Only such items / equipments which are
of proven design that have been in continuous satisfactory service on offshore
installation for a minimum period of two (2) years are accepted for use on the
offshore platforms.
Leaflets / catalogues / drawings / sketches of the particular product being
supplied – This is necessary to ensure that the offered product can meet the
necessary technical specifications.
Details of their Indian Vendors (in case of foreign vendors) and sub-suppliers,
viz. the name(s) of Manufacturer etc. for easy correspondence and after-sales
requirements
Quality assurance Manual for review by Offshore Design Section, to analyze the
schemes for product quality assurance, storage and traceability of products,
quality assurance and quality control procedures.
The Supplier’s Company profile with details of organogram & facilities to assess
the capability of the personnel to assist in testing and commissioning activities.
All items that are procured by the turn-key contractor for use / installation on offshore
platforms are subjected to inspection and testing by the Offshore Design Section /
Certifying Agency (CA) appointed by the Offshore Design Section / the turn-key
Contractor and / or a Third Party Inspection Agency (TPIA) appointed by the turn-key
Contractor & authorized by the Offshore Design Section. According to the type of
inspection carried out on the product, the product is classified as Category A, Category B
or Category C.
•
Category A Item:
Items under this category are inspected by the Certifying Agency (appointed by
the Offshore Design Section) either stage-wise or at the final stage. The result of
this inspection is submitted to the Offshore Design Section for review. This
inspection is in addition to the inspection carried out by the turn-key Contractor
/ the TPIA.
•
Category B Item:
Items under this category are inspected by the turn-key Contractor / the TPIA
during the intermediate and / or final stages. The inspection report is then
submitted to the Offshore Design Section / the CA at the fabrication yard to
obtain clearance for usage of the material / equipment.
•
Category C Item:
The material test certificates / compliance reports for items under this category
are submitted to the turn-key Contractor for review. If these documents are
found in order, the turn-key Contractor endorses them as “Reviewed &
Accepted”. These duly endorsed documents are then submitted to the Offshore
Design Section / the CA at the fabrication yard to obtain clearance for usage of
the material / equipment.
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ANNEXURE – I
LIST OF COMMONLY USED BARGES
S.
No.
1
2
BARGE
DLB
REGINA
250
GAL
CONSTR.
YEAR
OF
CONST
N
CRANE
TYPE
CAPACITY
TOTAL
BOOM
LENGT
H
CAPACITY
AT BOOM
LENGTH
1978
CLYDE 4063
250 MT
57.9 M
250 T
AT 18M
300 T
61 M
150 T
AT 45’
180’
150 ST
AT60’
1978
3
DLB/DB
NAVAJO
4
WB 80
5
JWB 250
6
SARMAX
UTAMA
1981
7
SARMAX
2000
1991
8
JAVA
CONSTR.
1982
9
WB 97
1983
10
11
12
SARKU
SAMUDR
A
SEABULK
OFFSHOR
E
SEABULK
MAIMTAINER
-
1980
1969
1983
1973
1966
13
SUBTEC-1
1977
14
SCANLAY
-1
1982
4100 VICON
WITH RINGER
AMERICANREVOLVER
356
MANITOWAC4000 CRAWLER
MANITOWAC4100 CRAWLER
AMERICAN
HOIST 9310
CRAWLER
AMERICAN
HOIST 9320
CRAWLER
PADASTAL
MOUNTED
AMERICAN
HOIST
AMERICAN
HOIST
AMERICAN
HOIST-11760
-
150 T
140’
225 ST
150’
250 ST
170’
200 ST
280 T
280 T
200’
33.5MT
AT 12.2M
73MT
AT 12M
-
200ST(180M)
AT 80’
150’
-
150’
127 ST AT
28’
MANITOWAC4000W
CRAWLER
-
-
33.5MT AT
12.2M
RADIUS
-DO-
-
-
-
-
-
82MT AT
8.5M
-
-
-
MANITOWAC4100
DETAILS
NOT
SUBMITTED
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ANNEXURE – II
LIST OF FUNCTIONAL SPECIFICATIONS USED BY OFFSHORE DESIGN SECTION
MECH
ANICA
L
PIPELINE
Discipline
S.
No
Spec. No.
1
2011
Submarine pipeline route surveys
2
2012
Coal tar Enamel coating of submarine pipelines
3
2013
Concrete weight coating of submarine pipelines
4
2014
Field Joint coating of submarine pipelines
5
2015
Installation of submarine pipeline and related facilities
6
2015 A
7
2016
Anodes for cathodic protection
8
2017
Anode Installation of submarine pipeline
9
2018
Long radius bends submarine pipelines
10
2019
welding
11
2020 A
Carbon steel seamless line pipe for submarine pipelines
12
2020 B
Carbon steel seamless line pipe for submarine pipelines (sour
service)
13
2020 E
Flexible pipes
14
2021
Trenching & backfilling of submarine pipelines
15
2022
Hydrostatic testing of submarine pipelines
16
2024 A
Fittings & flanges for submarine pipelines
17
2024 B
Fittings & flanges for submarine pipelines( sour service)
18
2025 A
19
2025 B
Sub sea ball valves
20
2028 A
Sub sea Flow tees
21
2028 B
Sub sea Flow tees ( sour service)
22
2029 A
Sub sea Pig signalers
23
2072 B
Sub sea butterfly valves for SPM( sour service)
1
5001
Centrifugal Pump
2
5002
Equipment Noise Limit
Description
Installation of submarine flexible pipes
Sub sea ball valves
( sour service)
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INSTRUMENTA
TION
Discipline
S.
No
Spec. No.
3
5003
Heat Exchanger
4
5004
Equipment Vibration
5
5005
Reciprocating Pump
6
5009
Reciprocating Compressor
7
5011
Skid Mounted Separator
8
5012
HVAC
9
5014
Shell & Tube Head Exchanger
10
5015
Air Cooled Exchanger
11
5018
Gas Turbine
12
5052F
Deck Crane
13
5055F
OCI Transfer Pump
14.
5055C
Reciprocating Pump – Controlled Volume
15
5056F
Rotary Gear Pump
16
5100W
Packaged Equipment for well platforms
17
5100P
Packaged equipment for Process platform
18
5101
Safety Studies
19
5102
Safety specifications
20
5103W
Commissioning procedure for well platform
21.
5103P
Commissioning Procedure for process platform
22
5104
HSE Requirement
23
5105
FGC
1.
3100
Level Gauge
2.
3101
Level Switch (Pneumatic)
3.
3102
Level Switch (Electrical)
4.
3103
Level Transmitter
Description
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ISNTRUMENTATION
(Contd.)
Discipline
S.
No
Spec. No.
5.
3200
Flow Switch
6.
3201
Flow Totalizer
7.
3202
Electronic Flow Transmitter
8.
3203
Orifice Plate
9.
3204
Restriction Orifice Assembly
10.
3205
Senior Orifice Assembly
11.
3206
Rotameter
12.
3207
Turbine Flow Meter
13.
3208
Coriolis Meter
14.
3209
MPFM
15.
3210
Gas Flow Computer
16.
3211
Liquid Flow Computer
17.
3300
Temperature Gauge
18.
3301
Temperature Switch (Electrical)
19.
3302
Temperature Transmitter (Electronic)
20.
3400
Differential Pressure Gauge
21.
3401
Pressure Gauge
22.
3402
Pressure Switch (Electrical)
23.
3403
Pressure Transmitter (Electronic)
24.
3500
Fire & Gas Detection System
25.
3501
Shut Down Panel (Pneumatic)
26.
3502
Telemetry Interface Cabinet
27.
3503
Instrumentation for Equipment Package
28.
3600
Hi-Lo Pilot Switch
29.
3601
Pressure Indicating Controller
30.
3602
P / I Converter
Description
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ELECTRICAL
PIPING
Discipline
S.
No
Spec. No.
31.
3603
Recorder (Electronic)
32.
3604
Recorder (Pneumatic)
33.
3605
Portable Calibrator
34.
3607
Filter Regulator
35.
3700
Control Valve
36.
3701
Safety Relief Valve
37.
3702
Self Actuated Pressure Control Valve
38.
3703
Deluge Valve
39.
3800
Chlorine Analyzer
40.
3801
Corrosion Analyzer
41.
3802
Dissolved Oxygen Analyzer
42.
C100
Distributed Control System
43.
C101
Programmable Logic Controller
1
2004-A
Specification for piping design
2
2004-B
Specification for piping fabrication & installation
3
2004-C
Specification for unfired pressure vessels
4
2004-D
Specification for piping specialties
5
2004-E
Specification for flexible piping
6
2006
1.
4011-P
Emergency Generator & Accessories
2.
4012-P
L.V. Switchgear
3.
4013-P
Battery & Battery Charger
4.
4014-P
Navigational Aids
5.
4016-P
Lighting & Power Distribution Panel
6.
4017-P
Medium & High Voltage Cables & Accessories
7.
4018-P
FRP Cable Trays
8.
4019-P
Aviation Marker Lights
Description
Specification for insulation of piping & Equipment
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Discipline
S.
No
Spec. No.
Description
9.
4020-B
Cathodic Protection System for structures with Monitoring System
10.
4021
Light fittings & Junction boxes
11.
4022
Explosion proof Plugs & Sockets
12.
4023
Industrial type Plugs & Sockets
13.
4024
Explosion proof Control / Local Push Button Stations
14.
4025
Industrial type Control / Local Push Button Stations
15.
4026
Div-2 Explosion proof light fittings and junction boxes
16.
4027
Self contained Emergency Luminaries
17.
4028
Neutral Grounding Resistors
18.
4029
Heaters & Controls
19.
4030
Communication cables
20.
4031
Paging & Intercom System
21.
4032
Radio system
22.
4033
Automatic telephone exchange
23.
4034
Close circuit TV (CCTV) system for process area monitoring
24.
4035
Uninterrupted power supply (UPS) system
25.
4036
Motorized actuator for valves (MOVs)
26.
4037
Generator relay control, synchronizing & load shedding panel
27.
4038
Fixed type Alok Chauduri & DC Distribution Boards
28.
4039
HV metal clad switchgear
29.
4040
Synchronous Generator & Accessories
30.
4042
Power distribution transformer (Cast Resin type)
31.
4001
Electrical work
32.
4002
Electrical work of skid mounted equipment
33.
4003
Electrical Heat Tracing
34.
4004
HV Motors
35.
4005
MV Motors
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STRUCTURAL
Discipline
S.
No
Spec. No.
36.
FS-4001
Cathodic protection of offshore structures
37.
FS-4002
Cathodic protection of submarine pipeline
38.
FS-4003
Navigational aids
39.
FS-4003SPM
Navigational aids for SPM
40.
FS-4004
Lighting and power distribution board
41.
FS-4005
FRP cable trays
42.
FS-4006
Light fitting and junction box
43.
FS-4007
Solar power system
44.
FS-4008
MV Motors
45.
FS-4009
Lighting Transformer
46.
FS-4010
Emergency Light
47.
FS-4011
Electrical Cable
48.
FS-4012
Explosion proof control station
49.
FS-4013
LV Switchgear
50.
FS-4014
Motorized actuator for valve
51.
FS-4016
Electrical Heat Tracing
52.
FS-4017
Electrical equipment with packaged plant
53.
FS-4018
Boost charging at well platform
54.
FS-4019
Intrinsically safe walkie talkie set technical specification
1
6001
General Specification for material fabrication & installation of
structure
2
2005
General Specification for protective coating
Description
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ANNEXURE III – SUGGESTED LIST OF SUPPLIERS
MECHANICAL
Discipline
S.
No
1.
Equipment / Material
Deck Crane
Supplier
a)
b)
c)
d)
e)
f)
g)
Weatherford, USA
Favelle Favco, Australia
Manitowak, USA
Seaking, USA
Nautilus, USA
Raina Engineers,Mumbai
American Aero, USA
2.
Pneumatic Pumps
3.
Vessels
a)
b)
c)
d)
e)
L&T, Hazira/Powai
R.D.Engineers, Mumbai (India)
Kilburn, Mumbai (India)
BHEL, Trichy
MIS, Sharjah
4.
Test Separator
a)
b)
c)
d)
Deutche Babcock, AbuDhabi
MIS, Sharjah
IMS, Italy
L&T, Hazira (India)
5.
Inst./Utility
System
a)
b)
c)
d)
e)
f)
Dodwell, Japan
Tide Air Inc. USA
McNeill & Magor, Mumbai (India)
Howmar
Nigata, Japan
Kilburn,Mumbai
6.
Chain Pulley Block
a)
b)
c)
d)
e)
f)
Ingersoll Rand, USA
Beebe International Inc. USA
Dresser, USA
Ajmeera, India
Kito, Japan
Air Dyne
a) Haskal Energy, UK
b) Nikkiso, Japan
Gas
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Offshore Design Manual
MECHANICAL (Contd.)
Discipline
S.
No
7.
Equipment / Material
Heat Exchangers
8
Produced Water
Conditioning System
9.
Fire Water Pump
Supplier
a)
b)
c)
d)
e)
f)
g)
h)
i)
a)
b)
c)
d)
e)
f)
a)
b)
c)
d)
e)
f)
g)
h)
i)
j)
BHPV, India
EBM-Hudson, Italy
IMB (Industrie Meccaniche Di Bagnolo spa)
Italy
Nuovo Pignone SPA, Italy
OLMI SPA, Italy
HHI, KOREA
Belleli Energy srl, Italy
L&T, India
Kavery, India
Skimovex dv. Netherland
Wemco, USA
Pertolite
Technomirk with Snam
Axsia Serck Baker,
Petreco, UK
Weir Pumps, UK
Pompes Guinard, France
Fluid Power, USA
Peerless Pumps, USA/Australia
Ingeroll Rand UK, USA
Worthington Pumps, UK
Thompson Pumps
KSB Pumps, Germany
Ebara Corporation, Japan
SPP, UK
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140
Offshore Design Manual
MECHANICAL (Contd.)
Discipline
S.
No
10.
Equipment / Material
Utility Generator
11.
Instrument Air
Compressors
12.
Chlorinators
Supplier
A.GENERATOR
a) AVON – KAICK
b) KATO
c) ALSTHOM
B.ENGINE
a) Fuji Electric, Japan
b) Cooper Energy Services
c) MAN AND B&W Engine, Germany
d) OT-Waltsila
e) Suizer Brothers Ltd.
f) Societe Alsacienne Deconstr Mecan
g).Compagnia Genesale Tractore SDA
h) FIN Cantieri Div.Grandi Motor
i) MAN-UNTERREHMNSBERI CH.
Diesel Motoren A.G.
C. ENGINE SUPPLIER AND PACKAGER
a) Steward & Stevenson, USA
b) Geveke Motoren, Netherlands
c) Caterpillar, USA
d) KATO, USA
e) Ruston Diesel, USA
f) Wankesha Pearce Ind.Inc, USA
g) Cummins, USA
h) Detroit Diesel, USA
i) Regon Equpt.Co.USA
a)
Tide Air
b)
Atlas Capco
c)
Worthington Turbodyne
d)
Bellies Morcom
e)
Norwalk, USA
f)
Compare, UK
g)
Ingersoll Rand, USA/India
a)
b)
c)
d)
e)
Electro Catalytic
Engel Hard, UK
Diaki Engineering Co. Ltd, Japan
Mistsubishi Heavy Ind.Japan
Petreco International, UK
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141
Offshore Design Manual
Discipline
S.
No
13
14
MECHANICAL (Contd.)
15.
Equipment / Material
Supplier
Sea Water Lift Pumps
a)
b)
c)
d)
e)
f)
g)
h)
i)
j)
Weir Pumps, UK
Pompes Guinard, France
KSB, Germany
Ebara Corporation, Japan
Worthington Pumps, Italy
Thompson Kelly & Lewis
DMW, Japan
UPC, USA
SPP, UK
BPCL, India
Fuel Gas Conditioning
And Compressors
a)
b)
c)
d)
e)
f)
g)
Petreco, UK With Peter Brother
Paladon, UK
Ingersoll Rand, USA
Cenatco, UK
IHI, Japan
Axsia Serck Baker
Alien Process Ltd, UK
Process gas compressor
module
(Vendors to meet Bid
Evaluation Criteria and
other Bid Specification)
A) PROCESS GAS COMPRESSOR
a)
M/s KHI, Japan
b)
M/s IHI, Japan
c)
M/s Dresser Rand, USA
d)
M/s Copper Energy Services, USA
e)
M/s MAN Turbo, Germany
f)
Elliott (now owned by Ebara, Japan)
g)
M/s Solar Turbines Inc, USA
h)
M/s Demag – De Laval (Siemens
AG, Germany)
B) GAS TURBINES
a) M/s General Electric, USA
b) M/s Rolls – Royce, UK
c)
M/s Alstom (M/s EGT), UK
d) M/s Solar Turbines, USA
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142
Offshore Design Manual
Discipline
S.
No
16.
Equipment / Material
TURBINE
GENERATOR SET
(Vendors to meet Bid
Evaluation Criteria and
other Bid Specification)
Supplier
A) GAS TURBINES
a) M/s General Electric, USA
b) M/s Rolls – Royce, UK
c) M/s Alstom (M/s EGT), UK
d) M/s Solar Turbines, USA
B) ALTERNATORS
a) M/s Brush Electric, USA
b) M/s General Electric, USA
c) M/s Siemens, Germany
d) M/s Alstom, UK
e) M/s Fuji Electric, Japan
Dry Chemical Skid
2.
Portable
Extinguishers
3.
Life Preservers (Life
Jackets)
Life ring Buoys),
Inflatable Life Rafts,
First Aid Kits,
Fire Blanket, Fireman’s
Outlet, Breathing
Equipment
Stretcher, Personnel
Baskets
Scramble nets
a) Ahmed. S. Moloobhoy & Sons. Mumbai
b) Meridian Inflatable Pvt. Ltd., Mumbai
c) Aero marine Industries Pvt. Ltd., Madras
d) Wormald Fire Engg. USA
e) Houston Fire & Safety Eqpt. Co. USA
f) Alexander Industrial INC. Houston
g) Keegan Speciality, USA
h) Billy Pugh Co. Inc,USA
i) Eastern Stores,Mumbai
j) Galvianiser,Mumbai
k) Mercantile & Marine Services ( I ) Pvt. Ltd.
Mumbai, India
4.
Eye Wash & Safety
Shower
a) Unicare Emergency Equipment, M’bai
b) Offshore Clothing and Suppliers Ltd.UK
c) Nippon Encon. Mfg. Co. Ltd. Japan
5.
Helicopter Rescue Kit
a) Bristol Uniform Ltd., Bristol, UK.
b) Wormald Fire Engg. USA
c) Houston Fire Safety Eqpt. Co., USA
d) Doopley Fire Systems Inc. USA
e) Joseph Lesilic & Co., Mumbai, (Inida)
f) AMCO, USA
SAFETY ITEMS
1
a)
b)
c)
d)
Fire
a)
b)
c)
d)
e)
Ansul Fire Protection, USA
Safety & Health, USA
Wormald, USA
Fire Boss, USA
Kooverji Devshi & Co. Pvt. Ltd. Mumbai
Wormald Fire Engg. USA
Houston Fire Safety Eqpt. Co., USA
Doopley Fire System Inc., USA
Zenith Fire Services, Mumbai (India)
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Offshore Design Manual
INSTRUMENTATION
Discipline
S.
No
6.
Equipment / Material
Personnel
Protection
Eqpt. From
H2S Exposure
Supplier
a)
b)
c)
d)
e)
Wormald Fire Engg. USA
Dooley Fire Systems Inc., USA
Nohmi Fire Safety Eqpt. Co. USA
Houston Fire Safety Eqpt. Co. USA
Drager Aktiengesell Schaft, Germany Joseph
Lesilic & Sons, Mumbai (India)
f) AMCO, USA
Interface a)
Marine Electricals, Mumbai (India)
b)
Fabricon, Mumbai
c)
Switch Gears & Control, Mumbai (India)
d)
Elec. Mech. Corporation, Mumbai (India)
e)
Marine Delight, Calcutta (India)
f)
YEW, Japan
g) Backer-CAC, USA
h) Yokogawa Blue Star, India
1.
Telemetry
Cabinet
2.
Well Fire Shutdown a)
Panel & Test Separator b)
Shutdown Panel
c)
d)
e)
f)
g)
Backer CAC, USA
Haven Automation, Singapore
Brisco Engineering, UK
Autocon, USA
Petrotech, USA
Bousted Services,Singapore
Wormald,UK
3.
Pneumatic
Pr.Switch/HI-LO Pilots
(Indicating dial type)
BACKER CAC, USA
WKM, USA
Axelson, USA
Petrotech, USA
Helliburton Energy
SOR, USA
Danfoss, India
ITT Neo Dyn., USA
Aschroft, USA
YEW, Japan
Delta Controls, USA
Backer CAC, USA
Dag Process (I)
IMI Bailey Birkit, UK
Sapag – Alshom, France
Anderson Greenwood, USA
Fukui, Japan
Crosby, UK
Teledyne Farris Engineering, USA
Moorco (India) only for NON-ASME Service
Triangle, UK
AUDCO India Ltd.
4.
5.
a)
b)
c)
d)
e)
Pr. Switches (Explosion a)
Proof)
b)
c)
d)
e)
f)
g)
h)
Pr. Relief Valves
a)
b)
c)
d)
e)
f)
g)
h)
i)
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Offshore Design Manual
Discipline
S.
No
6.
ISNTRUMENTATION (Contd.)
7.
Equipment / Material
Pr.
Controllers
Indicating
Supplier
a)
b)
c)
d)
e)
f)
Yokagawa, Japan
Fisher, UK
ITT Barton, USA
Foxboro, USA
Taylor, India/USA
ABB-Kent, UK
A) Large Case Field
Recorders
a)
Taylor, India
b)
Fox Boro, USA
c)
ITT Barton, USA
d) Yokagawa, Japan
B) Field
Integrators
a) Taylor, India
b) Yokagawa, Japan
Pneumatic
8.
Gauge Glass & Cocks
a)
b)
c)
d)
e)
f)
g)
h)
i)
Daniels, USA
Nihon Klinger, Japan
Patrole Services, France
Jerguson Gauge & Valve Company, USA
Chemtrols, Mumbai (India)
Protolina, Mumbai (India)
Samil, Korea
Penburty, USA
Technomatic, India
9.
Level
Instruments
(Pneumatic
(Level-controls & Level
Switches)
a) MSW Controls, UK
b) Fisher Controls, UK
c) Magnetrol, Belgium (only Level Switches)
d) Masoneilan, France (only Level controls)
e) Eckardt, Germany (only Level-controls)
f) S.O.R.USA (only Level Switches)
g) Backer CAC, USA (only Level-switches0
h) Chemtrols (I) (only Level-switches)
10.
Level
Switches
(Explosion Proof)
a)
b)
c)
d)
e)
f)
g)
SOR, USA
Petrol Service, France
MSW Controls, UK
Tokyo Keiso, Japan
Magnetrol Intl, Belgium
Dag Process (I)
Chemtrol (I)
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145
Offshore Design Manual
ISNTRUM
ENTATIO
N (Contd.)
ISNTRUMENTATION (Contd.)
Discipline
S.
No
11.
Equipment / Material
Supplier
Pressure Gauges
a)
b)
c)
d)
e)
f)
g)
h)
Gauges Bourden, UK
Bundenberg Gauges, UK
Aschroft, USA
ITT Barton, USA
Ametek, USA
Manometer India
WIKA, Germany
General Instruments
12.
Differential
Pr.
Gauges/Indicators
a)
b)
c)
d)
e)
f)
g)
Burdon, France
Gauges Bourdon, UK
ITT Barton, USA
WIKA, Germany
Meriam Inst., USA
Aschcroft, USA
Barton Inst. UK
13.
Pr. Transmitters/P to I
Convertors
14.
Solenoid Valves
15.
Turbine Flow Meter
16.
Temperature
Transmitters
a) Gould, USA
b) Instrumentation Ltd. Kota (India)
c) Rosemount, Mumbai (India)
d) Taylor, Faridabad, India
e) Rosemount, Singapore
f) YEW, Japan
g) Honeywell,USA
h) ABB-Kent, UK
i) Youogawa Blue Star,India
j) Fisher Controls,UK
k) Amerson Process
a) SCO, USA
b) Blackborough,UK
c) Maxseal, UK
d) Skinner, USA
a) Daniels, USA
b) Bopp & Reuther, Germany
c) Flow Tech. USA
d) Moorco, India
e) Smith, USA
f) Brooks Inst. USA
g) ITT Barton, UK
h) FMC Sammar
a) Rosemount, Singapore
b) Yokagawa, Japan
c) Schlumberger
d) ABB- Kent. UK
e) Honeywell, USA
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146
Offshore Design Manual
ISNTRUMENTATION
(Contd.)
Discipline
S.
No
17.
Temp. Gauges
18.
ESD & FSD Valves
19.
Temp. Switches
20.
Fusible Plugs
21.
Flame Arrestors
22.
Orifice Plates & Flanges
and Restriction Orifices
23.
Senior, Junior Simplex
Orifice Fittings
Filter regulators
24.
25.
Equipment / Material
Flow
Switches
Pneumatic & Electric)
Supplier
a) Ascroft, USA
b) Gauges Bourdon, UK
c) Nagano Keili, Japan
d) General Inst.Mumbai (India)
e) A.N. Instruments (I)
f) WIKA, Germany
a) Baker CAC, USA
b) Sigma USA
c) Protection system & Devices, India
d) Versa, Neitherland
a) Delta Controls, UK
b) ASCO, USA
c) KDG Instruments, UK
d) Nagano - Keiki, Japan
e) SOR, USA
f) ITT-Snider
g) Aschcroft – Dresser, USA
a) Baker CAC, USA
b) Sigma, USA
c) Ruelco, USA (M/s Nisson Consultant,Mumbai)
a) Petrols Service, France
b) Groth Equipment Corporation USA
c) GPE Controls, USA
d) Braunsch Weigr, Germany
e) Whersoe, S.A France
f) Shand & Jurs, USA
g) Marvac, UK
h) Safety System, UK
a)
b)
c)
d)
e)
Perry Equipt. Corpn, USA
Daniels, USA
Taylor, India
Micro Precision, Faridabad (India)
General instrument consortium (Mumbai)
a) Daniel, USA
b) Perry Equipment Corpn., USA
a) Shavo Norgen, Madras (India)
b) Fisher Controls, UK
c) Masoneilon, France
d) Taylor, India
a) MSW, UK
b) Magnetrol, Belgium
c) Tokyo Keiso, Japan
d) Link, USA
e) Yokogawa Blue Star, India
f) ITT Barton
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147
Offshore Design Manual
Discipline
S.
No
26.
Equipment / Material
A) Control Valves
B)
Self
Pressure
Valves
27.
Gas Detection Systems
28.
Deluge Valve with Test
Facility
29
Water Cut Meter
30
Rota Meter
ISNTRUMENTATION
(Contd.)
a) Fisher Controls, UK
b) Masoeneilon, France
c) Blake Borugh, UK
d) Motoyama Engineering Works, Japan
e) KOSON, Singapore
f) ABB-Kent, UK
g) Weir valves & controls, UK ltd
a) Fisher Controls, UK
b) Masoeneilon, France
c) ESME, UK
d) Weir valves & controls, UK ltd
a) Seiger, UK
b) General Monitors, UK
c) Haven Automation, Singapore
d) Detronics, USA
e) Delphian, USA
a) George Kent, Singapore
b) Wormald, Hong Kong/Singapore
c) Cla-Val, USA
d) MIL Ltd.
a) Emerson process
33
a) AL Flow Glass Equipment, India
b) Tyco Kiesco Co. Ltd. Japan
Distributed Control
a) Foxboro, USA
System
b) Baily Controls, USA
c) Toshiba, Japan
d) Honeywell, USA
e) Yokogawa, Japan
f) Fisher Rosemount, UK
g) Yokogawa Blue Star, India
Fire and Gas Detection a) Nohmi Bosai, Japan
System
b) G.P.Elliot, UK
c) Safety Systems, UK
d) ICS, UK
e) Seiger, UK
f) Yokogawa Indl.Safety System,Malaysia
Dew point analyzer
a) M/S Panametrics,USA
34
Data logger
31
32
1.
PIPING
Actuated
Control
Supplier
Pipe (Duplex SS)
a) M/S Econ instruments
b) Flueke
a) Sumitomo Corporation, Japan
b) Kawasaki, Japan
c) NSC, Japan
d) Sandvik, Sweden
e) Avesta, Sweden
f) Mannesmam, Germany
g) NKK, Japan
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Offshore Design Manual
PIPING (Contd.)
Discipline
S.
No
2.
Fittings (Duplex SS)
3.
Flanges (Duplex SS)
4.
Ball Vales (D.S.S)
5.
Shutdown Valves DSS
6.
Other Valves (Gate
Globe, Check)
D.S.S.
7.
Pipe (NACE C.S.)
Equipment / Material
Supplier
a) Sumitomo, Japan
b) Sandvik, Sweden
c) Shmoda Iron Works Co.Ltd.,Japan
d) Coprosider Spa, Italy
e) Mannesmann Rohren, Germany
f) NKK, Japan
a) Sumitomo, Japan
b) Sandvik, Sweden
c) Nicola Galperti & Figlio, Italy
d) Coprosider Spa. Italy
e) Mannesmann, Germany
f) Melesi,Italt (for sub-sea flanges)
a) KTM, Japan
b) Kitz, Japan
c) Deutsch Audco. Germany
d) Argus, Germany
e) Grove Italia Spa. Italy
f) T.K.Valves(Abu Dhabi) |Ltd.
g) Petrol Valves,Italy
a) KTM, Japan
b) Kitz, Japan
c) Deutsch Audco. Germany
d) Argus, Germany
e) Grove Italia Spa. Italy
f) T.K.Valves (Abu Dhabi) |Ltd.
g) Petrol Valves, Italy
a) Kitz. Japan
b) KTM, Japan
c) Rona Valves, Belgium
d) Petrol Valves, Italy
e) T.K. Valve (Abu Dhabi) Ltd.
f) Valvinox, Italy
a)
b)
c)
d)
e)
f)
g)
h)
Sumitomo, Japan
NKK, Japan
Nippon Steel Corporation, Japan
Mannesmann, West Germany
Misubishi Corporation, Japan
Dalmine Spa. Italy
Mitsui & Co. Kawasaki
Raccordi Forgiati, Italy (NACE PipesA106GB NACE pipe API 44 x 52)
i) Kawasaki, Japan
j) OMR Officine Meccaniche,Italy
k) Schulz Export EMBH, Germany
l) Engineering Supply EST
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149
Offshore Design Manual
Discipline
S.
No
8.
Fittings (NACE C.S)
9.
Flanges (NACE C.S)
PIPING (Contd.)
10.
Equipment / Material
Valves (NACE C.S)
Supplier
a) Sumitomo, Japan
b) Mega Spa. Italy
c) Gam Recordie, Italy
d) Raccordie Forgiati, Italy
e) Fittinox Sri Italy (A 105)
f) OMR Officine Meccaniche, Italy
g) Schulz Export EMBH, Germany
(NACE Fittings MSS-SP-75 WPHY 52 NACE Fitting
A234 WPB Seamless)
a)
b)
c)
d)
e)
f)
g)
h)
i)
a)
b)
c)
d)
e)
f)
g)
h)
i)
j)
k)
l)
m)
n)
o)
p)
q)
Sumitomo, Japan
Coprosider Spa. Italy
Nicoa Galpeti Figtio, Italy
Trouvay & Cauvin. France
Melesi, Italy
Ambrocio Melesi & C Sri, Italy (A 105 &
A694 F 52)
Galpeti (A 694 & A 105)
MGL,France
Schulz Export EMBH, Germany
Cameron Iron Works, USA
Grove Italia, Spa
KTM, Japan
Deutach Audeo, Germany
Argus, Germany
Kitz, Japan
Serck Audco Valves International UK
Flow Control Technology, France
Crane, USA
Orbit Valve, UK
T.K.Valve (Abu Dhabi)
Omb Spa, Spain (Upto 1.5” size)
Petrol Valve, Italy
Valvinox, Italy
Universal Sri. Italy NACE Ball Valve (4” &
Below)
Caslid NACE Gate, Globe, Check Valve
(above 2”)
Forged NACE Gate, Globe, Check & Needle
valve (2” & below)
LCM Italia SRL, Italy
SACCAP S.A. France
(Gate,Globe,Check&Needle Valves)
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150
Offshore Design Manual
Discipline
S.
No
11.
12.
Equipment / Material
Supplier
Shutdown Valves
NACE C.S
a) Grove Italia, Italy
b) KTM, Japan
c) Argus, Germany
d) Cameron Iron Works, USA
e) KITJ, Japan
f) Flow Control Technology, France
g) Crane, USA
h) Orbit Valves, UK
i) T.K. Valves, Abu Dhabi
a) BHEL, Trichy (Acceptable upto4”)
b) Indian Seamless, Ahmed Nagar
c) Jindal Pipes, New Delhi
d) Saw Pipes, Delhi
e) NSC,Japan
f) Mitsubhishi,Japan
g) MGL,France
a) Choksi Tubes, Ahmedabad
b) Kalindi, Delhi
c) NFC, Hyderabad
a) Alcabex Metals, Jodhpur
b) Cubex Tubing, Hyderabad
c) Lebronze Industrial,France
a) Eby Industries, Mumbai (India)
b) Shivananda Pipe Fittings, Madras (only
seamless)
c) Commercial Supplying Agencies, Mumbai
(India)
a) Echjay Industries, Mumbai /Rajkot
b) Paramount Forge, Mumbai (India)
a) BHEL, Trichy
b) AUDCO, India
c) Vergo Engineers, India
a) Sakhi Engrs. Mumbai/Baroda
b) Chemvalves Industries, Mumbai (India)
A) Pipe (Carbon Steel)
B) Pipe (Stainless Steel)
C) Pipes (Cu-Ni)
13.
Pipe Fittings in CS
(Both Seamless & Block
Forged)(All Indian
Vendors)
14.
18.
Forged Flanges in C.S
(All Indian Vendors)
Valves in C.S
(Both Cast & Forged)
(All Indian Vendors)
Needle Valves
(All Indian Vendors)
C.S
A) Ball
Valves
(Fire Safe) C.S
B) Ball
Valves
(Non Fire Safe) C.S
Cu-Ni Pipes & Fittings
19.
Gasket
PIPING (Contd.)
15.
16.
17.
a) L&T/Audco, India
b) Pertrol Valves, Italy
•
L&T/Audco, India
a)
b)
c)
d)
a)
b)
Yorkshire Imperial Metal, UK
Le Brone Industrial, France
Dia Yung Metal Industrial Co-Busan, Korea
V.D.M., Germany
Madras Industrial Product, Madras
IGP, Madras
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Offshore Design Manual
PIPING (Contd.)
Discipline
S.
No
20
Scrapper Tees
21.
Hinged Closures
22
Corrosion Probes
23.
Pig Detector
a) Pipeline Engineering & Supply Co.UK
b) TD Williamson, USA
24.
FWFM Reels & Utility
Hose Reels
a) Marine Hydraulic, Mumbai (India)
b) Royal India Corporation, Mumbai (India)
c) Gayatri, Mumbai (India)
25.
Strainers
a) Armstorng, USA
b) Multitex Engineers, New Delhi
c) Greaves Cotton, Delhi
26.
Spray Nozzles
a) Marine Hydraulics, Mumbai (India)
b) Wormald Fire system, UK
27.
Continuous Drainers
28.
5D Bends
a)
b)
c)
d)
e)
29.
Chemical & Utility
Hoses and Hose
Connection
a) Marine Hydraulics, Mumbai (India)
b) Gaytri Industries Corporation, Mumbai
(India)
c) Royal India Corporation, Mumbai (India)
30.
Choke Valves
Equipment / Material
Supplier
a)
b)
c)
d)
TD Williamson, USA
Pipeline Engineering Supply, UK
Schulz Export EMBH, Germany
GD Engineering, UK
a) Perry Equipment Corporation, USA
b) TD Williamson, USA
c) Pipeline Engineering Supply, UK
a) Casasco Division, USA
b) Rehrback Cosasco, USA
c) Mc Murray, USA
d) Caproco Intl. Canada
e) Atel, Italy
f) Corrocean, Italy
a) Armstrong, USA
b) Greaves Cotton, Mumbai (India)
Fabricom, Belgium
Sungjin Korea
Igawara, Signapore
PSL,Kandla (India)
Induction Bending
a) Modveld, USA
b) Petrol Valves, Italy
c) Valvinox, Italy
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152
Offshore Design Manual
ELECTRICAL
Discipline
S.
No
31.
Hand Control Valves
32.
Sample Bomb
33.
Launcher/Receiver
1.
Transformers
Resin Type)
2.
UPS System
3.
LT Switch Gear
Equipment / Material
(Cast
Supplier
Mansoneilan, France
Mokveld, USA
Fisher Controls,USA
Koson Process Controls, Singapore
Kent Process Control Ltd.,UK
Control Component Inc.,USA
Hoppkinsons Blackborough,Dubai
a) Harsh Engineering, Mumbai (India)
a) Pipeline Engineering,UK
b) T D Williamson,USA
c) L&T, India
a) Westing House, USA
b) General Electric, USA
c) Fuji, Japan
d) Mat & Christie
e)Traftech
f)Toshiba, Japan
g)Maidensha
h)Merlin Gerlin
i)GEC, UK
j)Toshiba, Japan
k)Kirloskar Power, India
a)SAB-NIEF, Sweeden
b)Stand By Power, USA
c)Chloride System, UK
d)Fuji, Japan
e)GUTOR, Switzerland
f)Emerson, USA
a)Westing House, USA
b)General Electric Co., UK
c)Hitachi, Japan
d)Toshiba, Japan
e)Fuji, Japan
f)L.K.Nes, Singapore
g)Nuovo Magnini, Italy
h)Aplerre
i)IME-Quadri
j)Abbott Power, USA
k)Merlin – Gerlin, USA
l)Martelli Electo Technical
m)Pan Electirc
n)Helco, Korea
o)Terasaki, Japan
p)L&T, India
http://www.infraline.com – Your Information Gateway to Indian Energy Sector
153
Offshore Design Manual
ELECTRICAL (Contd.)
Discipline
S.
No
4.
Equipment / Material
HT Switch Gear
5.
Battery
Charger
&
Battery
6.
Cathodic
System
7.
Fluorescent/Incandesce
nt
Class
`B’LTG
Fixtures
8.
Navigational
Aids
System (NAVAID)
9.
Lead Acid Batteries
(Solar Power System)
10.
Multi Cable
(MCT)
11.
Div.2 Aviation Marker
Ltg. Fixtures
Protection
Transit
Supplier
a) Westing House, USA
b) Hitachi, Japan
c) General Electric Co., UK/USA
d) SACE, Italy
e) ABB, Norway
f)Merlin Gerlin, USA
g)Siemens, Germany/Indonesia
h) Fuji, Japan
a) SAB-NIFE
b)Stand By Power, USA
c)Chloride System, UK
d)Yuasa, Japan
e)Fuji, Japan
f)Gutor, Switzerland
g)Emerson, USA
h)HBL NIFE, Hydrabad (India)
a) Impalloy, Singapore/UK
b) Alico Industries,UAE
c) Aluminium Pechinary, France
d) Nippon Corrosion, Japan
e) Nakagawa Corrosion, UK
f) Willson, India
g) PSL, India
h) Emirates-Techno Casting LLC, Dubai,UAE
a) Heyes Lighting,UK
b) Crouse Hinds, USA
c) Appleton, USA
d) ITO-Denki, Japan
a)
b)
c)
d)
e)
a)
b)
c)
d)
e)
Automatic Power Inc, USA
Tideland Singnal Corp, USA
TATA BP, India
SOLAPAK, UK
BP SOLAR, Australia
VARTA BATTERIES, Germany
Heagen Batteries, Germany
Chloride Batteries, UK
Amaraja Batteries, India
Yuasa, Japan
a) A.B. Lykab, Sweeden
b) Engtek Pte Singapore Ltd, Singapore
c) S.V.T.International, Germany
a)
b)
c)
d)
GEC Electrical Project Ltd, UK
Transberg A/S, Sweeden
DTS, France
Tide Land Signal, USA
http://www.infraline.com – Your Information Gateway to Indian Energy Sector
154
Offshore Design Manual
ELECTRICAL (Contd.)
Discipline
S.
No
12.
Equipment / Material
Lighting
&
Power
Distribution Panel
13.
Solar Power System
14.
FRLS Cables
15.
Fire Survival Cables
16.
Fiber Glass Cable Trays
Supplier
a) Morarji Dorman, Mumbai
b) Indo Asian Switch Gear, Jullundhar, India
c) Versatrip Circuit Breaker Mfg.(P) Ltd.,
Mumbai, India
d) Bhartiya Cutler Hammer, Faridabad, India
e) Reunion Engg. Co, Mumbai
f) Fabricons, Mumbai
g) Siemans, Germany / India
h) Willson & Co, India
a) Central Electronics Ltd, Faridabad, India
b) BHEL, India
c) Tata BP Solar, India
d) BP Solar, Australia
e) Solapak, UK
a) Universal Cables, Satna, India
b) Nicco Cables Co. Ltd, Kolkata, India
c) Cable Corporation Of India, India
a) Universal Cables, Satna, India
b) INCAB, India
c) Cable Corporation Of India, India
a)Super
Reinforced
Plastics
Engg.Corp., Mumbai, India
b)Grip India, Mumbai
c)SSB Industries, Bangalore, India
d)Ercon Composites, Jodhpur, India
http://www.infraline.com – Your Information Gateway to Indian Energy Sector
Associated
155