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Composite
comfort
Tim Mally, Citadel Technologies, USA, explores how
carbon fibre composite repair systems are rapidly gaining
traction in the budget-minded and engineering driven oil and gas
industry as an acceptable method to restore pipeline integrity.
W
ith the recent plunge in oil prices on the West Texas
Intermediate (WTI) dropping below US$50/bbl, oil and
gas operators are scrambling to thin out labour and trim
down the fat on their operating budgets. Meanwhile, lower
operating budgets have not absolved their responsibility to maintain a
safe and reliable pipeline network managed through a pipeline integrity
management programme.
To add to the chaos, many pipeline safety regulators around the world,
such as the US’ Department of Transportation’s Pipeline and Hazardous
Materials Safety Administration (US DOT’s PHMSA), are cracking down
on ageing and potentially unsafe pipeline infrastructure within their
respective countries. The only item that seems to be increasing
as fast as the amount of pipeline regulations is the cost
of the penalties for non-compliance. As these two
factors constantly swirl in pipeline owners and
operators’ minds, they are daily faced with
decisions of which outcomes will
directly effect how efficiently
and economically they can
Figure 1. BlackDiamond®
is leading a composite
repair revolution that
is helping to change
the way that pipeline
operators approach their
everyday integrity digs.
keep their pipelines safe and intact for the surrounding
population.
With budgets and safety setting the stage at the
forefront of their minds, operators are looking for trusted
tools that can safely and economically repair and maintain
their pipelines. Enter carbon fibre composite repairs as
a safe and reliable means of saving money and restoring
pipeline integrity. One composite repair that operators
have placed their trust in is BlackDiamond®, which is a
strength restoring blend of aerospace-grade carbon fibre
and high quality two-part epoxy. Manufactured by Citadel
Technologies in Tulsa, Oklahoma, BlackDiamond has been
developed, laboratory tested and designed by engineers
specifically for the pipeline industry.
The engineering staff at Citadel Technologies have
partnered with several pipeline operators over the years
to utilise BlackDiamond to solve common integrity issues
with ease in the field. These operators sleep well at night,
knowing that they are using a product to repair their
pipelines that has been rigorously tested in the laboratory
and proven with successful applications worldwide. This
unique blend of peer-reviewed testing and field experience
is rapidly bringing unprecedented industry acceptance to
advanced composite repair systems as a means of restoring
pipeline integrity.
Composite science
Figure 2. BlackDiamond repairs have been installed worldwide
for almost 20 years.
Figure 3. When properly designed, a BlackDiamond repair is
stronger than the original pipe itself.
Figure 4. Air-to-ground pipe transitions often experience
corrosion and are typically in need of repair.
World Pipelines / REPRINTED FROM MARCH 2015
According to the US DOT Code of Federal Regulations
(CFR) Parts 192 and 195, “corroded pipe may be repaired
by a method that reliable engineering tests and analyses
show can permanently restore the serviceability of the
pipe.” Although this is a vague definition, the ASME
PCC-2 committee has been tasked with quantifying
which tests and analyses are needed in order to guide
pipeline operators in qualifying composite repairs as an
acceptable means of permanent pipeline remediation.
ASME PCC-2 Article 4.1 (for non-metallic repairs on
high risk piping applications), in particular, provides a
roadmap for the qualification testing that a composite
repair system must undergo to meet the rigorous pipeline
repair criteria of operators around the world. While
composite manufacturers previously cornered the market
on developing and understanding this article, more and
more pipeline operators are diving into the process of
editing and contributing to the development of this repair
standard. Such a shift in participation can indicate that
composites are rapidly gaining acknowledgement as a
legitimate permanent pipeline repair option, signalling
more widespread acceptance and use from major oil and
gas companies.
Although optional for the PCC-2 Standard, there
are several long-term tests that can be performed on
composite repair systems to demonstrate reliability as
a “permanent repair solution.” Creep tests, fatigue tests,
burst tests, etc. can all be performed on the composite
system according to ASTM standards to prove the
effectiveness of composite repairs over a long-term
design life. BlackDiamond’s repair components have been
tested in the lab to have a minimum 50 year life according
to creep tests. Figure 3 demonstrates an example of
fatigue tests proving that BlackDiamond can survive
greater than 110 000 cycles of pressure cycle fatigue
and is still stronger than the original pipe. Along with
the PCC-2 qualifying tests, these tests more than qualify
BlackDiamond as a permanent repair solution in line with
DOT regulations.
Composite advantage
Traditional repair methods, such as full pipe cut out and
replacement, welded steel sleeves and clamps, have been
accepted industry-wide for longer than composites have
been a repair option. To initiate a mindset change among
pipeliners who have used these methods for their entire
careers is nigh impossible. However, even the staunchest
supporter of traditional repair methods would be forced
to consider the several advantages that carbon fibre
reinforced composites offer upon closer examination.
When compared with welded sleeves, maybe one of
the clearest advantages of a pipeline integrity-restoring
composite repair is the absence of hot works. No welding
is required for wet lay up wraps, therefore many of the
problems that occur from welding are eliminated. Strength
reducing heat-affected zones and stress corrosion cracking
can potentially occur when welding on pipelines. Both
of these issues reduce pipeline integrity, and are avoided
when utilising a composite repair solution.
Certified and qualified welders are a precious
commodity worldwide. Composite repair installations
do not require the same level of schooling and training.
Although composite installation training is important
and should not be overlooked, a composite repair can be
applied by a less experienced labour force much quicker
and cheaper than traditional repair methods.
Additionally, a BlackDiamond installation can be made
in-situ without reducing pipeline pressure and does not
require shutdown of the pipeline. Operation of the line
in question continues and saves the operator the costs
associated with production loss that would otherwise be
lost when cutting and replacing or welding a metal sleeve
that require the line to be shut down.
However, many pipeline operators are not yet ready
to completely switch over to composite repairs. For
those that are hesitant to diversify from traditional repair
methods, there are some situations where composites
have the clear advantage over welded metallic repairs.
BlackDiamond proves its mettle over traditional repair
methods with ease of installation on field bends, pipe
fittings, and complex geometries while maintaining desired
pipeline production levels. If shutdown is not possible or
is too inconvenient for a cut out and replacement, then
carbon fibre composite repairs hold a major advantage
when repairing these geometries. Welded sleeves are
not a valid repair option for many field bends. Wet layup
Figure 5. The first step in the process is to fill the external
damage with a load transferring filler putty.
Figure 6. The use of a bucket enabled certified installers to access the full length of pipe requiring repair.
REPRINTED FROM MARCH 2015 / World Pipelines
composite repairs are easily manoeuvred to install and
cure around these odd shapes, restoring the strength of
the pipe in these bends to restore the pipe back to its
MAOP.
As operators determine whether composite repairs
such as BlackDiamond are the right fit for their repair
needs, situations such as field bend repairs will help
composites quickly gain approval and acceptance within
stringent, engineer-driven oil and gas companies.
Composite connection
One major pipeline operator in the US and Caribbean has
been on the cutting edge of pipeline repair technology
through the use of composite repairs for many years. As
a pioneer in the use of composite repairs, this pipeline
operator has expanded their use of BlackDiamond to
include the repair of field bends, corrosion anomalies,
mechanical damage, and manufacturing defects in the pipe.
Roger Clark, Certified Inspector for Pugh Pipeline
Services, is a big proponent of using BlackDiamond to
restore pipeline integrity for pipeline operators such
as this one. According to Roger, BlackDiamond has
“saved them [the pipeline operator] a lot of money over
traditional repair methods through the years.” This pipeline
operator also recognises that BlackDiamond will not only
restore his externally corroded and mechanically damaged
pipelines to their original operating strengths, but it will
also prevent future external corrosion as well. With years
World Pipelines / REPRINTED FROM MARCH 2015
of experience under his belt, Roger can spot a potential
opportunity to use a composite repair, and is trusted
by both the pipeline operator and the composite repair
company to carry it out with the utmost efficiency and
quality.
Roger recently supervised an installation on a 30 ft
span of 8 in. dia. pipeline with a field bend where access to
the pipe was limited. A welded sleeve was not an option
due to the pipe geometry, and the pipeline operator could
not afford to shut down in order to cut and replace due
to the high demand of the contents within the pipe and
the costs associated with a full shutdown. Roger ensured
that the BlackDiamond repair was installed by certified
installers, and utilised his vast BlackDiamond experiences
to organise an assembly line to speed up installation.
The engineered composite repair was installed and cured
within the day, and returned the pipeline to its original
strength to the highest satisfaction of the operator.
In cases like this, the pipeline owner knew that they
could trust composite repairs to get the job done. A
significant body of evidence was presented to prove
BlackDiamond’s mettle on the laboratory scale, and a wellqualified team led by an experienced supervisor carried
out what would have been an otherwise difficult repair.
The pipeline operator will continue to turn to composite
repairs in 2015 as a suitable pipeline repair method that
may soon be the worldwide repair of choice.