Y o u r
V a l u e
P a r t n e r
Weholite
Manual
© Copyright Marley Pipe Systems (Pty) Ltd 2014
www.marleypipesystems.co.za
About Us
Marley Pipe Systems have been
manufacturing SABS approved
products since consumer protection was
first mandated in the industry.
In keeping with international trends,
Marley is a market leader in converting to
lead free materials.
Marley’s commitment to quality and safety
has all pipes and components manufactured in an ISO9001 accredited facility.
01
About Us
Your TRUE Value Partner
Marley Pipe Systems is the leading manufacturer and distributor of plastic pipes and fittings for reticulation systems,
serving the key market segments of the plumbing and building industries as well as the infrastructure sector
throughout sub-Saharan Africa.
We at Marley Pipe Systems are dedicated to serving our clients with quality solutions, expertise, dedication, passion
and integrity and, as an Aliaxis company, we bring solutions, new technology and expertise on a global level to the
local market, ensuring our clients are always ahead of the times. Add to this a commitment to providing only the best
in technical support, expertise, integrity and service delivery, and you've got a true Value Partner in Marley Pipe
Systems.
Today, the Marley Pipe Systems team consists of over 880 people with the manufacture of all pipe and fittings taking
place at Nigel and Rosslyn in Gauteng.
Vision
Values
To become the preferred and most respected
distributor and manufacturer of quality plastic pipe
systems for the Building, Civils, Mining, Irrigation and
Industrial markets in sub-Saharan Africa.
Purpose
To grow responsibly towards becoming a truly regional
(sub-Saharan Africa) player represented in major
centres, manufacturing fast moving product ranges at
local plants across the region as well as providing a
wholesale offering on group and externally produced
products.
Y o u r
V a l u e
•
Integrity
•
Honesty
•
Passion
•
Reliability
•
Trust
•
Accountability
•
Compassion
•
Professionalism
•
Respect
•
Commitment
•
Excellence
•
Ethics
P a r t n e r
www.marleypipesystems.co.za
-
-
Introduction
Introduction to Weholite
Polyethylene is recognised by clients and engineering consultants alike as the ideal pipe
material for many pressure and non-pressure applications – from water distribution to gravity
sewers, rehabilitation projects and manholes to marine pipeline applications.
Recognising clients’ needs for large diameter, lightweight, low-pressure pipes and fittings,
Marley now offers Weholite, a pipe constructed by a patented structured wall process that
allows the manufacture of diameters from 280mmm up to 3500mm.
Weholite is manufactured in Finland, Sweden, Poland, South Africa, the United Kingdom,
Canada, Malaysia, Oman, Iceland, Italy, Chile, Japan and Thailand and is steadily gaining
ever wider acceptance in other countries worldwide.
03
Weholite Applications
Landfill Drainage
Mine Drainage
1500mm Weholite shaft with stepladder and Solid-Wall
HDPE piping. Landfill drainage site, Gauteng.
300mm Weholite pipe perforated for mining drainage
pipe.
Attenuation Application
Fittings/Specials
Stormwater attenuation application.
Marine Pipeline Application
Standard conditions of tender and sale apply.
A copy of these conditions can be forwarded
upon request
04
Weholite Applications
Weholite structured wall HDPE pipe provides all the raw material advantages of equivalent polyethylene solid-wall
pipes, but with substantial savings in weight, thus combining greater ease of installation with increased cost
effectiveness.
Weholite pipe represents the latest advances in both material and manufacturing technology. Its unique structure
offers a range of pipe sizes and ring stiffnesses, depending on customer requirements. The combination of raw
material properties and product technology provides a lightweight engineered pipe with superior capacity for
various municipal, industrial, road-building, rehabilitation and marine pipeline applications.
Sewer Pipelines
Pipe Rehabilitation
1250mm outfall sewer. Blackburn, Durban.
Rehabilitation of a corrugated galvanised pipe.
Stormwater
Culverts
3m x 700mm stormwater pipe lengths being laid in
Cullinan.
05
Product Range & Dimensions
SWP (Structured Wall
Pipe) Weholite
Marley manufactures Weholite pipe under licence
from Uponor Infra (formerly KWH Pipe). Weholite
pipes are manufactured in accordance with Uponor
Infra and Marley internal standards which are in
accordance with EN 13476 and SANS 21138 and
form part of an SABS ISO 9001:2008 quality management system. Regular inspections and audits are
carried out by the local inspection authority.
The pipe design allows for a minimum design life of 50
years under specified design and installation
parameters. The material selection process is the
same as that used for pressure pipe applications.
Research has shown that the service life of Weholite
will be at least 50% greater than concrete, and in
corrosive applications, at least 100% greater than
concrete.
Weholite structured wall
HDPE pipes are supplied as
follows:
Stormwater
Sewer
Sandtight male-female
coupling, no seal
= OGEE joint
“Watertight” socket and
seal for DN560 pipes
are welded in situ
Threaded joint*
D≥1200mm pipes
Standard lengths
3m, 6m, 12m
(24m pipes may also be specified)
Standard lengths 6m, 12m
*Stiffness design is according to ISO 9969
Weholite pipe sizes:
Pipe CD/ID (mm)
Max Pipe OD (mm)
2kN/m2
Max Pipe OD (mm)
4kN/mm2
8kN/m2
Max Socket OD (mm)
280
300
350
400
450
500
560
600
700
750
800
900
1000
1100
1200
1250
1500
1800
318
334
385
439
484
555
616
665
765
840
878
980
1105
1177
1305
1350
1685
2022
318
341
404
454
505
565
638
677
790
840
903
1016
1128
1254
1354
1400
1685
2022
390
415
476
526
576
636
708
747
865
919
980
*N/A
*N/A
*N/A
*N/A
*N/A
*N/A
*N/A
Sizes larger than 1800mm upon request
Dimensions are indicative and may change from time to time
*For watertight joint, pipes need to be extruder welded
*A subject to availability
06
Product Range & Dimensions
Stormwater
280-500mm Sewer Pipe
Female socket, sandtight (geotextile may be required)
Socket with seal – watertight
Threaded Joints
Threaded Joint Details:
(Sandtight) Welded for watertightness
Nominal Size
DN/ID
B
A
B ≥ 0,5 Profile Height ≤ 0,75 Profile Height
DN<500
500
560
600
700
750
800
1000
1100
1200
(A) Min Thread
Length mm
100
130
146
155
170
175
180
200
200
240
07
Double Sockets
NS = di
mm
De
mm
L
mm
M
mm
Do
mm
280
300
350
400
450
500
560
600
700
750
800
900
1000
1100
1200
315
338
400
450
505
560
618
675
788
844
900
1013
1125
1238
1350
628
684
740
796
830
916
960
1042
1166
1180
1200
1300
1400
1400
1400
199
206
220
248
278
308
240
371
433
442
450
500
550
550
550
364
388
438
488
550
602
660
705
830
900
944
1050
1170
1280
1395
Flange Joints
Double-socketed standard fitting
Joint
DN
mm
280
300
350
400
450
500
560
600
700
750
800
900
1000
1100
1200
Weholite
De
mm
315
338
400
450
505
580
618
675
788
844
900
1013
1125
1240
1360
NS=di
mm
280
300
350
400
450
500
560
600
700
750
800
900
1000
1100
1200
PE Pipe
De
mm
280
280
355
400
450
500
560
360
710
710
800
900
1000
1000
1200
L
mm
377
377
377
385
380
379
390
390
400
410
415
430
438
440
460
Flange
D
mm
412
412
505
565
670
670
780
835
895
955
1015
1115
1230
1343
1455
b
mm
22
22
28
32
36
38
50
40
50
50
56
56
60
60
60
k
mm
350
350
376
430
473
515
691
703
725
770
815
915
1015
1115
1215
Bolts
pcs
x size
Bolts
Torque
Nm
12XM20
12xM20
16xM20
16XM24
20XM24
20XM24
20XM27
20XM27
24XM27
24XM27
24XM30
28XM30
28XM33
28XM33
32XM36
34
38
45
60
65
70
86
88
90
95
100
115
130
138
141
Dimensions are calculated values and may vary from the finished product
Flange drillings are dimensioned according to customers’ requirements
08
Stub End
h
mm
34
34
40
44
44
44
50
56
56
60
70
86
88
96
100
d4
mm
320
320
430
482
485
485
685
685
805
853
900
1005
1110
1220
1330
Bends
Bends 1° - 30°
Bends 31° - 60°
Bends 61° - 90°
Double-socketed Standard Fittings
NS=Di
mm
de
mm
R = 1,0
x NS
mm
30°
Z
mm
Ze
mm
45°
Z
mm
Ze
mm
60°
Z
mm
Ze
mm
90°
Z
mm
Ze
mm
280
300
350
400
450
500
560
600
700
750
800
900
1000
1100
1200
1250
1500
1800
315
338
400
450
505
560
618
675
788
844
900
1013
1125
1240
1350
1575
1680
2016
280
300
350
400
450
500
560
600
700
750
800
900
1000
1100
1200
1250
1500
1800
267
312
357
402
450
499
550
602
703
730
758
858
935
1049
1012
911
975
1170
81
126
173
157
175
191
191
231
270
379
308
487
385
678
464
540
604
799
352
412
472
532
590
661
730
797
931
980
1018
1118
1260
1344
1402
1365
1460
1752
166
226
252
284
315
353
371
426
498
629
468
747
710
973
852
994
1089
1381
331
361
421
541
557
572
692
811
947
992
1037
1160
1283
1357
1430
1398
1495
1794
235
244
261
296
331
365
403
440
514
551
587
660
733
807
880
930
1100
1300
473
547
621
695
750
865
900
1041
1215
1250
1344
1443
1667
1709
1891
1936
2073
2488
309
355
401
447
500
557
620
670
782
820
894
1000
1117
1200
1341
1400
1700
2000
Dimensions are calculated values and may vary from the finished product. Tolerances for pipe lengths
Z and Ze are ±50mm (+23°C). Other angles and bend radii can be supplied on request.
Dimensions above 1800mm will be designed individually to meet customer requirements, transport possibilities, etc.
09
Equal Tees
Double-socketed Standard Fittings
NS 1
mm
de 1
mm
NS 2
mm
de 2
mm
Z1
mm
Z2
mm
Z 2e
mm
Z3
mm
Z 3e
mm
280
300
350
400
450
500
560
600
700
750
800
900
1000
1100
1200
1250
1500
1800
315
338
400
450
505
560
618
675
788
844
900
1013
1125
1238
1350
1575
1680
2016
280
300
350
400
450
500
560
600
700
750
800
900
1000
1100
1200
1250
1500
1800
315
338
400
450
505
560
618
675
788
844
900
1013
1125
1238
1350
1575
1680
2016
365
424
483
542
600
674
750
812
947
1000
1038
1150
1284
1362
1431
1400
1500
1800
365
424
483
542
600
674
750
812
947
1000
1038
1150
1284
1362
1431
1400
1500
1800
226
238
263
294
325
366
391
441
576
629
667
779
913
991
1060
1029
1129
1429
365
424
483
542
600
674
750
812
947
1000
1038
1150
1284
1362
1431
1400
1500
1800
226
238
263
294
325
366
391
441
576
629
667
779
913
991
1060
1029
1129
1429
For branches (NS 2<NS 1), lengths Z3 and Z3e are equal to above. Dimensions are calculated values and may
vary from the finished product. Tolerances for pipe lengths Z and Ze are ±50mm (+23°C).
Dimensions above 1800mm will be designed individually to meet customer requirements, transport possibilities, etc.
10
Manholes
The Weholite manhole system provides solutions for all
sewerage and stormwater systems. Manholes are normally
prefabricated. Pipe connections can be manufactured to suit
any standard sewer pipe. The inclinations and angles of the
connections can be set as required. Standard manhole
covers will be selected according to application or traffic
loads. If required, ladders can be fitted inside the manhole.
Manholes for high water table are designed accordingly.
Reinforced concrete base to be designed to counter
buoyancy and to anchor HDPE puddle on manhole.
Manholes Lateral
Manholes Reducing
Manholes Straight or Bends
SHAFT
SHAFT
SHAFT
HDPE STEPS
HDPE STEPS
HDPE STEPS
Xo
Xo
Xo
Xo
Xo
BENCHING
BENCHING
BENCHING
Z1
di(ID)
I
di(
Z1
Z1
D)
Xo
Z2
Z2
Di(ID)
Di(ID)
Di(ID)
X = 15°
Z1 = 1,5m
Di(ID) = 1200mm
di(ID) = 497mm
X = 15°
Z1 = 1,5m
Di(ID) = 1200mm
di(ID) = 497mm
X = 15°
Z1 = Z2 = 1,5m
Di(ID) = 1200mm
Socket and seal included all round
Socket and seal included all round
Socket and seal included all round
Standard conditions of tender and sale apply. A copy of these conditions can be forwarded upon request
*Drawings indicative and can or may be changed
11
Designing with Weholite
Inherent Properties of Weholite Structured Wall Pipe
High Density Polyethylene
as a Material for Pipe
Construction
HDPE has long been considered ideal for sewer
applications. Owing to the economic advantages of
structured wall (or profiled-wall) technology, Weholite
HDPE pipe can now be used as an economic
alternative to traditional materials such as vitrified
clay, reinforced concrete (R/C), fibre cement (F/C)
pipes and corrugated galvanised steel.
Below, typical values can be used to perform structural design as per EN 1295-1.
Typical physical properties of Weholite pipe material
Unit
kg/m3
N/mm2
Mm/mM.k.
W/m°C
Corrosion and Chemical
Attack
Traditional pipe (concrete) materials may
suffer from bacterial or
chemical attack in a
corrosive
environment (such as
that encountered in
sewer and effluent lines).
HDPE is highly resistant to such attacks, making
Weholite an ideal alternative for long pipe service life.
For all practical purposes, PE is chemically inert in
normal use. Electrolytic and galvanic corrosion are
therefore eliminated. More information on the
chemical behaviour of PE is given in ISO 10358.
12
Value
>930
1000
13 x 10-5
0.3 – 0.4
0.4
Standard
ISO 1183
ISO 527
Abrasion
Asbestos cement pipe
3,0
Fibre glass
reinforced
pipe
2,5
Abrasion (mm)
Property
Density
E-modulus short term
Linear expansion coefficient
Thermal conductivity
Poisson’s ratio
2,0
1,5
Concrete pipe
Clay Pipe
1,0
PVC
0,5
0
HDPE
200 000
400 000
600 000
Load cycles N
In the Darmstadt abrasion test (DIN 19534, Part 2),
samples of commonly used pipe materials were filled
with a mixture of sand and water and subjected to a
specified number of rocking cycles. The amount of
abraded material was measured at regular intervals.
The result proved the very high abrasion resistance of
polyethylene pipe material – 400 000 load cycles
resulted in 0,3mm abrasion for PE pipes. Abrasion in
fibre-reinforced and concrete pipes was 6-8 times
higher.
Designing with Weholite
Inherent Properties of Weholite Structured Wall Pipe
UV Stability and
Temperature Range
In accordance with international material standards,
the HDPE grades used in Weholite production may be
UV stabilised by the addition of carbon black, making
Weholite almost impervious to UV attack.
The maximum permissible temperature of the medium
transported is:
+80°C (short term) and
+45°C (long term)
Product Advantages
Weholite has an effective double wall,
ensuring system integrity should the pipe be
damaged either externally or internally.
Scale and Sediment
Build-up
HDPE does not readily bond with or adhere to other
materials. This ensures that build-up does not occur,
and long-term flow characteristics are not affected
when Weholite is specified.
12m lengths offer a greatly reduced joint
frequency, which minimises the possibility of
leakage or ingress of groundwater
(which can lead to excessive loading of
downstream treatment plants).
Weholite offers superior crack resistance
due to the ability of the material to “unload”
excessive stress on to the surrounding backfill.
Such stresses (often caused by soil movement)
could result in failure of pipelines assembled with
rigid materials such as concrete and fibre cement.
Standard conditions of tender and sale apply. A copy of these conditions can be forwarded upon request
13
Weholite High Density
Polyethylene (HDPE) Resin
*Technical Specifications of HDPE Raw Material
Physical Properties
Density
Melt Flow Index (190C/21,6kg)
Melt Flow Index (190C/5kg)
Vicat Softening Point (5kg)
Crystalline Melting Range
Viscosity Number
Mechanical Properties
Shore D Hardness
Tensile Yield
Ultimate Tensile Strength
Ultimate Elongation
Elastic Modulus
Flexural Strength (3.5% Deflection)
Notched Impact (Charpy) can 23°C
Notched Impact (Charpy) can -30°C
Thermal Stability (OIT1, 210°C)
Carbon Black Content
ISO 1183
ISO 1133
ISO 1133
ISO 306
ISO 3146-85
ISO 1628
0.958
9.0
0.23
67
130-133
390
ISO 868
IS0 527
IS0527
ISO 527
ISO 527
ISO 178
ISO179
ISO 179
ISO 10837
ASTM D 1603
61
24
35
>600
900-1000
19
20
6
≥20
≥2
g/cm3
g/10 min
g/10 min
°C
°C
cm3/g
Mpa
Mpa
%
Mpa
Mpa
KJ/m2
KJ/m2
Min
%
1) OIT: oxidation induction time
* Alternative materials may be used from time to time
Standard conditions of tender and sale apply. A copy of these conditions can be forwarded upon request
Weholite Flow
Calculation
Hydraulic Design
Colebrook-White Formula
ʋ = kinematic viscosity (m2/s)
d = internal diameter (m)
g = acceleration due to gravity (9.81m/s2)
u = velocity (m/s)
l = hydraulic gradient (‰)
k = roughness coefficient (m),
Weholite pipe 0.03mm
14
Hydraulics
Owing to the low friction coefficient of HDPE, the
coefficient of friction of Weholite pipes is relatively low.
COLEBROOK-WHITE
MANNING
HAZEN WILLIAMS
k = 0.03mm
m = 0.01
C = 135
These figures are generally below those obtained with
new reinforced concrete pipe, and no adjustment (to
allow for corrosion, etc.) is required with Weholite pipe
designs (20% - 30% lower than used for concrete).
Designing with Weholite
Proportional Velocity and Flow Rate in
Partially Filled Pipes
Fil l i ng l e ve l %
100
Flow volume
Area
Velocity
Hydraulic Radius
80
Diagram showing the change of water flow volume,
filled area, flow velocity and hydraulic radius as a
function of the filling level in the pipe. (The 10 Q curve
illustrates an enlargement of the Q curve between 0%
and 12% on the horizontal axis)
Q
A
u
R
60
Q
A
40
U
20
R
10 Q
0
20
40
60
80
100
1 20
C h a n g e o f p ro p e rt y %
Example of the Change in Flow Volume and Velocity
Gradient
Filling
NS=400
NS=800
NS=1200
‰
1
Level
100%
50%
25%
u
m/s
0.60
0.51
0.33
Q
l/s
25
34
10
u
m/s
0.93
0.79
0.51
Q
l/s
465
219
61
u
m/s
1.19
1.01
0.66
Q
l/s
1348
607
175
100%
50%
25%
1.36
1.15
0.75
170
77
27
2.09
1.78
1.15
1052
473
168
2.69
2.29
1.48
3041
1369
487
100%
50%
25%
1.92
1.64
1.60
242
109
31
2.97
2.52
1.63
1492
671
194
3.81
3.24
2.10
4310
1940
560
5
10
15
Designing with Weholite
Discharge (ℓ/s) for Pipes with Full Flow
Roughness coefficient value for Weholite pipe 0.03mm
Roughness coefficient value of 0.25mm for the pipe system (diagram)
Kinematic viscosity of water at +10°C
Gradient ‰
Flow l/s
Gradient ‰
Flow l/s
•
•
•
Standard conditions of tender and sale apply. A copy of these conditions can be forwarded upon request
16
Loads on Buried Pipes
Weholite Loads on
Buried Pipes
Flexibility in Buried
Pipelines
In the case of low-pressure or thin-walled pipes, it is
frequently not the internal pressure but the external
pressure which dictates the pipe wall stiffness. A pipe
is less resistant to external loads than to internal
pressure, as the pipe wall acts in a different way.
Whereas internal pressure exerts pure tension on the
pipe walls, external loads may cause circumferential
or longitudinal bending, arching and even buckling.
A flexible pipe is by definition a pipe which will deflect
when subjected to external loads (traffic, ground water
changes, soil settlement, etc.) as opposed to a rigid
pipe, which carries all external loads by itself. The
degree of deflection of a flexible pipe will depend on
the pipe stiffness, support from the surrounding soil
and external loads.
External loads are not symmetrical; the vertical
loading due to soil pressure or superimposed loads is
greater than the lateral soil pressure. It is this
differential loading which causes bending of the pipe
wall.
There are several methods for calculating the
deflection in buried flexible pipelines. Most of them are
based on the so-called Spangler Formula:
Deflection (%) =
vertical load on the pipe
pipe stiffness + soil stiffness
Possible loads on a pipe
Pipelines are typically subject to:
a.
b.
c.
Vertical soil pressure
Superimposed live loads due to vehicles
Crushing or bending by heaving or moving soils
Causes of pipe failure
Excessive loads may result in failure due to:
a.
b.
c.
d.
e.
f.
g.
Crushing or compression of the pipe wall
Tensile failure
Bending of the pipe wall
Longitudinal bending
Excessive deflection
Buckling
A combination of any of the above
After installation, further gradual compaction of the
surrounding soil takes place due to external loading
and soil settlement. Experience shows that the
maximum deflection will be achieved within 1-3 years
after installation, depending on backfill material, the
quality of backfill compaction work and on external
loads. The maximum allowable deflection is 8-10%
(pipe and welded joints only) and 3-5% (joints).
A flexible pipe absorbs external loads and deforms to
a certain extent. A rigid pipe, on the other hand, by
definition cannot deform. When external loads
increase sufficiently, the rigid pipe will finally crack,
after which it starts to behave like a flexible pipe.
Pipes installed underground react to soil settlement
along the length of the pipeline. Loads/deflections
vary from place to place. Flexible pipes react to
additional settlement/loads by bending, while rigid
pipes react by angular deformation in the joints.
17
Loads on Buried Pipes
For alternative soil types, refer to table below.
For reference:
In accordance with pr EN 1046, A 127 and WG 14, the following soil types and groups have been proposed by G.
Leonhardt 1998/02/02 based upon recommendations given in British Standard BS 5930 and German Standard
DIN 18196:
Group 1: poorly graded gravel, single sized gravel
Group 2: granular soils, such as well-graded gravel, gravel-sand mixture, single sized sand, well-graded sand,
poorly graded sand-gravel mixture
Group 3: mixed grained soils with low fine fraction and some cohesion such as silty gravel-sand mixture, clay-like
gravel-sand mixture, silty sand, clay-like sand
Group 4: mixed grained soils with high fine fraction moderate cohesion such as very silty respectively clay-like
gravel-sand mixture, very silty respectively clay-like sand, silt of low plasticity
Group 5: fine grained cohesive soils such as inorganic silts respectively clay, grained soils with admixture of humus
or chalk, organic silt, organic clay
Initial Average Pipe Deflection % for Well Performed
Procedure at Depth of Cover 6m
% Deformation
Soil
Group
1
2
3
4
5
4 kN/m2
2 kN/m2
8 kN/m2
Short
Term
Short
Term
Max
Short
Term
Short
Term
Max
Short
Term
Short
Term
Max
Ave
1.7
2.0
2.4
3.2
3.6
Max
2.6
3.0
3.6
4.8
5.4
Long
3.4
4.0
4.8
6.4
7.2
Ave
1.6
1.8
2.2
2,9
3.2
Max
2.4
2.7
3.3
4.4
4.8
Long
3.2
3.6
4.4
5.8
6.4
Ave
1.4
1.6
1.9
2.4
2.6
Max
2.1
2.4
2.9
3.6
3.9
Long
2.8
3.2
3.8
4.8
5.2
If a structural design is required, e.g. in cases where no other information exists, then a method as defined in EN
1295-1 should be used. A Marley representative can also be contacted to assist through manipulation of variables
in a finite element design software package.
18
Design
The design requirements of Weholite allow the
engineer an optimum combination of pipe strength
and flexibility, and installation savings are normally
easily achieved compared with ridgid materials.
Loading / Deflection
Under loading, flexible pipes deflect, and Weholite
(which is viscoelastic) reacts similarly. Deflection is
vital, as it optimises the pipe/soil interaction and
ensures a crack-free system. Rigid materials cannot
interact with soils and have to bear loads entirely,
irrespective of soil stiffness. It is
important to contain deflection.
Three standard ring stiffness classes exist; 2 kN/m2,
4 kN/m2, 8 kN/m2 are applied as follows.
Stiffness design conforms to ISO 9969:
Ring stiffness,
Validity of the Design
Graph
The design graph is valid under the following
conditions:
•
•
•
•
•
•
RS ISO = EoI
D3m
Where Eo = 1000 N/mm2
I is calculated from the geometry of the true
profiled wall
Dm = Mean diameter of pipe
Design graph for pipe
selection
Based on the study (TEPPFA; 1999; Design of Buried
Thermoplastics Pipes), several design approaches
can be proposed. For thermoplastic pipes possessing
huge strainability, designs can be kept simple. It has
also been shown that more effort should be put into
the installation of the pipe, but not more than for rigid
pipes. An important observation is also that flexible
pipes follow the soil settlement, and behaviour is
managed by this. Load is therefore not an issue for
flexible pipes in well installed conditions. Therefore,
based on the results of this work, the design approach
using simple graphs is strongly recommended.
In the design, graphs-areas are given for each
installation group. The lower boundary of each group
represents the average deflection expected and upper
boundary the maximum.
The design graph contains three installation groups.
The add factors are fully linked to the type of
installation. The add factors or consolidation factors
(Cf) have to be added to the value for the initial
deflection which can be obtained from the graph.
•
Depth between 0.8m and 6m, both included.
Depth/diameter ratio at least above 2.0
Designers first need to establish permissible
deflections, average and maximum (national
requirements, product standards, etc.).
Pipes fulfil the requirements listed in the
Weholite internal standard and
international standards.
Installation categories “well”, “moderate” and
“none” reflect the workmanship on which the
designer can rely.
Sheet piles are removed before compaction.
If the sheet piles are removed after
compaction, the “well” or “moderate”
compaction level will be reduced to the “none”
compaction level.
For the deflection mentioned in the graph, the
strain will be far below the design limit and
need not be considered in the design.
Installation Types
As per ISO TC 138/sc1 and or ENTS 13476-3
Well
Well
Primary backfill:
granular type
Layer 30cm + compaction
Final backfill: soil of any type
+ compaction
Compaction: >94%
mod. Proctor
Cf = 1,0
Moderate
Moderate
Primary backfill:
granular type
Layer 50cm + compaction
Final backfill: soil of any
type + compaction
Compaction: 87 - 94%
mod. Proctor
Cf = 2,0
None
None
Backfill:
granular /cohesive type
Layers: without compaction
Compaction: <87%
mod. Proctor
Cf granular
Cf cohesive
= 3,0
= 4,0
19
Buckling
Weholite Design
Methodology
•
•
Ensure that Weholite pipes and variables
comply with variables referred to in the leaflet
on Pipelaying (Validity of the Design Graph).
Determine national long-term maximum
allowable circumferencial deflection % (Either
pipe or joint will prevail).
Example:
During the construction phase – before side fill is
compacted and soil stiffness is attained – the pipe is
subjected to full loading without support of the side fill.
A buckling check is done according to graphs below.
Buckling loads should never exceed 50% of the
predicted buckling strength (i.e. a safety factor of 2
against buckling must be observed).
For a firmly buried pipe, the buckling pressure Pbs can
be determined as:
Pbs = 5,63 √ SN•E’t
Pipe and extrusion welded joints / Threaded joints
2 kN/m2
4 & 8 kN/m2
Short Term
Long Term
5%
8%
8%
10%
Joints with or without rubber meal
2 kN/m2
4 & 8 kN/m2
•
•
•
Short Term
Long Term
2%
4%
3%
5%
Determine installation type.
Determine consolidation factor (Cf) in
accordance with installation type.
Determine maximum short-term allowable
deflection.
Example:
where:
Pbs = Buckling pressure (MPa)
SN = Ring stiffness (MPa)
E’t = Tangent modulus of the soil (MPa)
n = Safety factor (normally ≥2)
The value is theoretical limit. Under normal
circumstances, the safety factor against radial
buckling should never be less than 2.
Pperm = Pbs
n
Tangent Modulus for
Friction Soils
E’t (Mpa)
3,0
90
r
octo
. pr
od
%m
2,0
3,0
2,0
85 %
80 %
1,0
1
2
3
90
1,0
75 %
0
(δ/d) final = (δ/d) instantaneous + Cf
E’t (Mpa)
Ground water table below pipe
4
5
6
7 H (m)
Filling Height
%m
od.
ctor
pro
85 %
80 %
75 %
0
1
2
3
4
Filling Height
5
6
7 H (m)
Thus for a joint 2 kN/m2 pipe 3% long-term maximum
allowable deflection for well performed installation is
as follows:
Calculation example
•
Groundwater table below pipe
•
Filling height = 3m
•
Degree of compaction = 90% mod. Proctor
•
Ring stiffness of a pipe = 4 kN/m2 =
0,004 Mpa f
3% - 1% = 2%
from a table E’t = 2,5 MPa
Or maximum allowable for moderate performed
installation
Pbs = 5,63 √( 0.004 * 2.5)
= 0.563 MPa
Thus 3% - 2% = 1%
Pperm = 0,563/2
= 0,28 MPa
Thus (δ/d) instantaneous = (δ/d) final - Cf
Both conform to maximum stated in “Joints with or
without rubber seal”.
Standard conditions of tender and sale apply. A copy of these conditions can be forwarded upon request
20
Weholite Pipe Handling
Handling and Storage
Instructions
Correct loading and
unloading
Relevant national or local regulations must be
observed.
It is important that loading, unloading and handling be
performed safely to avoid damage to property or
equipment. As loading and handling can be a hazard
to persons in the unloading area, unauthorised
persons should be kept at a safe distance while
unloading.
General
Weholite pipes are sturdy and lightweight, which
makes them easy to use. Unfortunately, these properties also increase the temptation to abuse the pipe.
Proper handling is required to minimise the risk of
damage.
Pipes must be handled with sufficient care. They can
be damaged if dropped or thrown about. Pipes or
bundles of pipes must never be dragged – the pipe
surface may be weakened by scratches.
When transporting and storing pipes, care must be
taken not to permanently deform the pipes. Socketed
pipes in particular must be stored in such a way that
their sockets are not subjected to loading that will
cause deformation.
Adequate level space must be reserved for unloading.
Secure the truck on level ground as well. The
unloading equipment must be capable of safely lifting
and moving the pipe, fittings, fabrications, etc.
Off-loading may be done by means of skid timber and
strap slings or with mechanical lifting devices.
However, lifting chains, ropes or hooks may not be
used, as these may result in permanent damage to
the product. Lifting points must be well spread and
evenly spaced.
Transport and unloading
Pipes should be transported on flat transport beds
without sharp edges or other projections that might
damage the pipes. Movement or rubbing of pipes
during transport must be prevented, for instance by
strapping the pipes down. When pipes of different
sizes are transported, the heaviest lengths are loaded
underneath. If the pipes are transported nested inside
one another, the smaller pipes are removed first and
piled separately.
Upon arrival at the site, the pipe shipments are
visually inspected and checked against the packing
list for correctness in size, stiffness and quantity.
The pipes must also be inspected for damage which
may have occurred during handling and/or transport.
Obvious damage such as cuts, abrasions, scrapes,
tears and punctures must be carefully inspected and
noted. Any damage, missing items, etc. must be noted
on the bill of loading and signed by the customer and
the driver. Shipping problems such as the above
should be reported to the supplier immediately.
Single Pipes
When lifting single pipes, use pliable straps or slings.
Do not use steel cables or chains to lift or transport
the pipe. Pipe sections can be lifted with only one
support point, but especially for larger diameters it is
recommended to use two support points to make the
pipe easier to control. Do not lift the pipes by passing
a rope through the centre of the pipe end to end.
21
Weholite Pipe Handling
Nested Pipes
Preferred lifting technique
Always lift the nested bundle by at least two pliable
straps. Ensure that the lifting slings have sufficient
capacity for the bundle weight. Stacking of nested
pipes is not advised unless otherwise specified.
Storage
Inspect all materials carefully upon arrival on site and
note and report any defects immediately. All pipe
stacks must be made on firm, flat ground that can
support the weight of the pipes and lifting equipment.
For safety and convenience of handling, the stack
height for pipes is limited to five units or not more than
2.8m. Stacks must be adequately wedged to prevent
movement.
Normal stacking of plain
ended pipes
Pipes must be stored on intermediate supports
spaced not more than 2m apart. The support width
must be greater than the profile width of the pipe size
in question, but not less than 100mm. Pipes with
integral sockets must be stacked with the sockets at
alternate ends, or at least without loading the sockets.
Pipes with z-cut ends must be stored with the z-cut
oriented in the same position (at 12 o’clock). The
maximum storage height for pipe stacks is 2.8m
overall.
Besides protecting all material adequately against
theft, vandalism, accidental damage or contamination,
also keep pipes and fittings away from sources of heat
if at all possible. If the pipes are to be stored for long
periods, they must be protected against excessive
heat; storage at high temperatures for prolonged
periods can cause excessive deformation that may
affect installation.
To avoid this risk, the following precautions are
recommended:
a.
Shield the stacks against continuous and
direct sunlight and allow free passage of air
around the pipes;
b.
Store the fittings in boxes, sacks or shading
manufactured so as to permit free passage of
air;
c.
Protect elastomer sealing rings against direct
sunlight.
22
Stacking of socketed pipes
Weholite Choice of Stiffness
Weholite Choice of
Stiffness (SN) Series
General
Weholite pipes are flexible pipes. A flexible pipe
installed in the ground deflects during installation,
because of the force exerted on it, as well as after
installation, because of the further settlement of the
soil. The amount of deflection reached after
installation depends to a great extent on the quality of
installation and to a lesser extent on the pipe stiffness.
The increase in the pipe deflection after installation
depends on the amount the soil can settle after
installation. When the soil around the installed pipe is
well compacted, any increase in pipe deflection will be
very limited. If the soil compaction ratio is low, pipe
deflection will increase during settlement. Traffic load
does not affect pipe deflection other than increasing
the rate of settlement of the soil.
Procedure for Pipes
Prescribing a specific level of workmanship is the
surest way of controlling pipe deflection. It has been
proven that this parameter has by far the greatest
influence on deflection. If, however, the installation
procedure is fixed, then the choice of stiffness class
(SN) can be made on the basis of one of the following:
•
•
•
When reference situations exist: Has the same
class of pipe used under similar or more severe
conditions been found acceptable?
Based on the Design Graph, see leaflets on
Loads on Buried Pipes and Pipelaying
Based on structural design, see leaflet on
Pipelaying
Procedure for Fittings
Generally, fitting in accordance with this standard
should have the same stiffness class as the pipes to
which they are connected.
Fittings in accordance with EN 1401-1, 1852-1 and
12666-1 can be used in combination with pipes
according to this standard. Because these fittings are
classified by their wall thickness, their actual stiffness
is higher than that of a pipe with the same wall
thickness. Such fittings are used as shown in Table 1.
Table 1: Minimum fitting classes
recommended for use with structured wall pipes
Fittings according to:
Pipe
Stiffness ISO 9969 EN 1401-1 EN1852-1 EN12666
SN 2
SN 4
SN 8
SN 16
SN 2
SN 4
SN 8
SN 16
SDR 51
SDR 51
SDR 41
SDR 34
S 20
S 20
S 16
S 11.2
S 16
S 16
S 12.5
S 10
Where fittings of equal or higher stiffness than that of
the pipe(s) are not available, fittings of lower stiffness
may be used. In such cases guidance from the fittings
manufacturer or supplier should be sought.
Standard conditions of tender and sale apply.
A copy of these conditions can be forwarded
upon request
23
Weholite Jointing
Socket Jointing
(Elastomer Sealing Ring
Joints)
The integral socket joint can be delivered as sandtight
or watertight (with rubber seal). The rubber seal
conforms to international standards and is resistant to
normal sewage waters. Seals resistant to oil
contaminated water are available upon special
request.
Jointing must always be carried out in accordance
with sound civil practice. However, in the absence of
instructions the following is recommended:
a.
b.
c.
d.
e.
f.
24
Chamfer and deburr the spigot end when the
sealing ring is in position in the socket.
Use only sealing rings and lubricants supplied or
approved by the manufacturer of the pipe or
fitting.
Ensure that cuts made on site are square. If
necessary, set up a proper cutting zone. After
cutting, chamfer or deburr the end to produce a
finish equivalent to that of the pipe supplied by
the manufacturer. Open profile closure needs to
be repaired in pipes that will be air tested.
Clean the pipe end, the socket and the sealing
ring groove, removing any foreign matter, water,
sand, dirt, etc. Make sure the sealing ring sits
correctly in its location.
Apply lubricant over the whole chamfered end, in
the socket area or on the fixed sealing ring, as
appropriate.
Carefully align the spigot with the adjoining
socket and push to the required insertion depth
(depth of entry mark). If a lever is used on the
pipe to push the joint, insert a block of wood
between the lever and the end of the pipe to
prevent damage to the pipe.
Align the pipes vertically
and horizontally
Make sure that spigot end, socket and sealing
ring are free from sand, moisture, dust, etc.
Weholite Jointing
1.
Install the rubber sealing ring in the groove.
Make sure the tension in the rubber material is
distributed evenly by applying force to the rubber
ring.
2.
Apply lubricant evenly onto the spigot end and
the rubber sealing.
Welded Joints
Welded and fused joints should always be made by
qualified personnel and in accordance with the
manufacturer’s instruction and national standards.
Extrusion welding is used for gravity applications
where the joints must have full watertightness and
tensile strength, as well as 100% resistance to root
encrease. Welding will be undertaken by specially
trained operators either from the inside or the outside
of the pipe, or both.
3.
Gently push the spigot onto the socket using
adequate force until the stop mark (depth of
entry mark) made on site is at the socket
opening. Use a plate or plank to avoid damage
to the spigot or socket. Large dimensions may
be installed by using an excavator. Protect the
socket opening with a sheet or plank. Check that
the sealing ring stays in position.
25
Connection to Existing
Pipes
Weholite pipelines can be connected to existing
pipelines or to structured wall pipelines of a different
design in a way similar to a repair (see Repairs) by
using an appropriate fitting. For saddle connections,
follow the saddle manufacturer’s instructions.
Connection to Rigid
Structures
•
•
•
•
•
Pull the couplings over the joint so that they are
centrally located over the joints.
Check the line and level of the newly installed
pipe.
Tighten all bolt tensioners evenly so that all the
slack is taken up before tightening fully to
20-25Nm.
The embedment should then be replaced to give
compaction values approximately equal to those
immediately adjacent to the repair.
Prior to completing the backfill of the pipe, the
bolts must be retensioned. Ideally, LP
couplings should be retensioned on the morning
after the repair has been carried out.
A structure may be a wall of a building, an inspection
hole, other pipelines, fittings such as valves or the
like.
The connection of a Weholite pipe to a structure
depends on the pipe size as well as on the structure
at the connection point. Connections must be made in
such a way that the joint is tight and that no damage is
done to the pipe.
If a Weholite pipe is connected to a structure that may
settle differently than the pipe, a flexible connection
beneath the pipe in the vicinity of the structure must
be used, or a transition zone permitting pipe
movement, or a strengthening construction.
Special fittings for this purpose are available and must
be fitted in accordance with the manufacturer’s
instructions (short length double-socketed pipe).
Repairs
Slip couplers or purpose-designed fittings are
available for effecting repairs. It is recommended that
the following general points should all be adopted,
where applicable:
•
•
•
•
The full extent of the damaged or failed section
must be identified and removed.
The cut pipe ends should be square and
prepared for push-fit jointing.
LP repair couplings should be placed in
position on the exposed pipeline ends. The
replacement pipe length should then be laid on
the suitably prepared bed and the LP
couplings moved into their final positions.
Ensure that the bedding does not interfere with
the couplings and that the pipe ends are clean.
Wall Passings / Repairs
CONCRETE
STRUCTURE
DETAIL A
DETAIL A
CL OF PIPE
26
BOX SECTION OF WEHOLITE
PIPE CUT OUT AS SHOWN
Weholite Jointing
Threaded Joints*
1.
2.
1
Align the pipes vertically and horizontally.
Make sure that the threads are free from sand,
moisture, dust, etc.
Thread the male end into the female end.
The pipes can be rotated using a lever or
band-sling.
If necessary, an excavator can be used to help
rotate the pipes. To facilitate the rotation, the
pipes can be laid on planks or roller supports.
3.
4.
5.
The joint as such is sandtight. If watertightness is
required, the joint can be extrusion welded from the
inside (NS>800mm), from the outside, or both. The
joint can also be waterproofed using an external
shrink sleeve or rubber sleeve.
2
*Threaded joints subject to availability.
3
4
5
27
Weholite Jointing
Rubber-sleeve Joints
Rubber-sleeve (LP) couplings are designed for
jointing pipes in stormwater and other types of
non-pressure applications in the construction, repair
and maintenance of pipelines. These include:
•
Non-watertight jointing
•
As a joint for plain-ended pipes
•
Repair of existing pipelines
•
As an adapter between pipes of different sizes
or materials
Step 7:
Re-visit each nut to ensure the correct torque rating is
achieved.
Step 8:
The correctly assembled coupling should sit neat and
straight, centrally located over the 20mm gap between
the two pipe ends.
1
5
2
6
3
7
4
8
Fitting Instructions
Weholite LP Coupling
Step 1:
Pipe surface to be checked for damage.
If the pipe end is in a suitable condition, it should be
cleaned and marked with a line 150mm from the end.
The pipe end must be liberally greased to assist the
rubber sleeve to slide over the pipe end.
Step 2:
The entire rubber sleeve must be pushed onto one
pipe end.
The two pipe ends must be positioned with a setting
gap of 20mm.
The rubber sleeve must be slid back over the 20mm
gap between the two pipe ends. The gasket must be
located centrally between the marks made on each
pipe end.
Step 3:
The first outer strap must be positioned and finger
tightened in an outer groove of the rubber sleeve.
Step 4:
The second outer strap must be positioned and finger
tightened in the other outer groove of the rubber
sleeve.
Step 5:
The required size of socket (24mm) and the required
torque rating (45Nm) is specified on the sticker by the
fastening arrangement on the coupling.
Step 6:
Tighten the outer bolts to the recommended torque
rating of 45Nm.
Tighten the inner-sleeve bolts to the recommended
torque rating of 45Nm.
28
Weholite Jointing
GUIDELINE
2nd PIPE PLACED IN TRENCH,
WITH CORRECT HORIZONTAL
AND VERTICAL ALIGNMENT
LP COUPLING FITTED TO PIPE
BEFORE PLACING IN TRENCH.
APPLY LUBRICANT IF REQUIRED
1 000
DETAIL 1
PIPE BEDDING
REMOVED LOCALLY
25
25
SLIDE LP COUPLING
ACROSS THE JOINT
UNTIL IT IS EQUIDISTANT
BETWEEN THE GUIDELINES
Deviation from
straightness
It is normal practice in sewerage and drainage that
pipes are installed in straight lines. However, as
Weholite pipes are longitudinally flexible, it is possible
to bend them if required during the installation. In such
cases, minor misalignments of the pipeline can be
accommodated in the pipe itself by bending. The
minimum permissible bending radius for Weholite
pipes under normal installation conditions = 50 * De
(outside diameter). There may not be any bending at
the socket. An acceptable bending radius can be
maintained by lateral supports against the side of the
trench. Special care should be taken when bending
pipes at low temperatures, and the joint must be
protected against any extra stress.
The largest permitted angular deflection in the
elastomer ring seal joint (the design angle) is
PIPE BEDDING TO BE
REPLACED AND TAMPED
DETAIL 2 - LP COUPLING CORRECTLY POSITIONED
2° for de<315 mm
1.5° for 315≤de≤630
1° for de>630
Large angular deflections are permitted in the case of
joints specifically designed to accommodate such
deflections. The manufacturer of the coupling will
specify the permitted angular deflection.
DETAIL 3 - PLAN VIEW OF FINAL JOINT ALIGNMENT
(LP COUPLING OMITTED FOR CLARITY)
29
Weholite Pipelaying
Installation Types and
Related Consolidation
Deformation
“Moderate” compaction,
Cf=2.0
Design Graph
An intensive study of the deflection history of pipes
installed under different conditions is presented in the
graph.
The average deflections immediately after
installation are represented by the lower
boundary of each area, and the maximum
values by the upper.
12
“None” compaction in clay,
Cf=4.0
10
8
The embedment soil of a cohesive type is added
without compaction. Installation of this type is NOT
recommended.
6
NOT RECOMENDED
4
MODERATE
2
WELL
0
2
4
Cf = Consolidation factor.
8
16
Ring stiffness [kN/m 2 ]
Pipe deflection after installation
“Well” compaction, Cf=1.0
The embedment soil of a granular type is placed
carefully in the haunching zone and compacted,
followed by placing the soil in layers of 300mm
maximum, after which each layer is compacted
carefully. A layer of at least 150mm must cover the
pipe. The trench is further filled with soil of any type
and compacted. Typical values for the Proctor density
are above 94%.
30
“None” compaction in
granular soil, Cf=3.0
The embedment soil of a granular type is added
without compaction. Installation of this type is NOT
recommended.
( /d) inst
-2
The embedment soil of a granular type is placed in
layers of 500mm maximum, after which each layer is
compacted carefully. A layer of at least 150mm must
cover the pipe. The trench is further filled with soil of
any type and compacted. Typical values for the
Proctor density are in the range of 87-94%.
Weholite Pipelaying
Validity of the Design
Graph
The design graph is valid under the following
conditions:
•
•
•
•
•
•
•
Depth between 0.8m and 6m, both included.
Depth/diameter ratio at least above 2.0
Designers first need to establish permissible
deflections, average and maximum (national
requirements product standards, etc.).
Pipes fulfil the requirements listed in the
Weholite internal standard and international
standards.
Installation categories “well”, “moderate” and
“none” reflect the workmanship on which the
designer can rely.
Sheet piles are removed before compaction. If
the sheet piles are removed after compaction,
the “well” or “moderate” compaction level will be
reduced to the “none” compaction level.
For the deflection mentioned in the graph, the
strain will be far below the design limit and need
not be considered in the design.
Trench Work
Bedding
On the bottom of the trench, on top of an exchange
material or on top of a grating, a 150mm-300mm thick
bedding layer is prepared and well compacted (>95%
Proctor). The bedding may consist of sand, gravel or
crushed pebbles, free from stones within the width of
the pipe trench. The bedding needs to be at least
200mm wider than the pipe outside diameter to
enable proper compaction work. For installations in
wet or soft soil, a geotextile must be placed under the
bedding in order to prevent the bedding from being
washed away.
The largest permissible particle size dmax for natural
stone materials to be used is determined on the
outside diameter of the pipe to be installed. For
DN<600, dmax = 0,1 • DN. For DN>600, dmax is always
60mm. Crushed pebble material must not be larger
than 32mm and/or in accordance with national standards.
If a pipeline is founded directly onto levelled native
soil, the trenching work must be done carefully,
avoiding unnecessary over-excavation, in order to
keep the trench bottom sufficiently level. The whole
bedding layer depth must be stone free.
The size and shape of the trench are planned on the
basis of the size of the pipe or pipes to be laid as well
as the soil data gained from soil investigations. The
trench is generally made as narrow as possible, taking
into account the width needed for possible supporting
structures, working space and space needed for
proper placement of the backfill soil. The minimum
width of the bottom of an open trench is 0.7m and that
of a supported trench 1.0m. Making a trench
unnecessarily wide should be avoided, as the effect of
the side support might be weakened.
When determining the trench depth, sufficient space
for a bedding layer of at least 150mm must be taken
into account, should the native soil be suitable as
bedding. The final excavation is made carefully, so
that the bottom of the trench is kept as undisturbed as
possible. Moving about on a soft or easily disturbed
trench bottom must be kept to a minimum.
The slope of a trench wall and the need for support
are determined on the basis of appropriate needs and
general workplace safety aspects. The slope
inclination and need for support are specified in the
national standard specification for civil engineering
construction.
Laying
Before starting to lay the pipe, check that the pipes
and materials to be used are free from defects. Clean
them carefully after transportation and any machining
done before installation.
The pipes are laid on the levelled trench bottom or
bedding so that the pipe is supported evenly over its
full length. Excavations are made in the trench bottom
or bedding for the sockets, so that the weight of the
pipes do not rest on the sockets. Do not lay pipes on
top of wooden planks or similar.
31
Weholite Pipelaying
During laying, the water level in the trench must be
kept sufficiently low to prevent flotation or water from
damaging the laid pipe. When laying work is
interrupted, the ends of the pipes must be sealed to
prevent ingress of dirt or water.
The final layer of the primary backfill must extend
300mm above the crown of the pipe; to avoid ovalisation of the pipe, the soil layer on top of the pipe can
only be mechanically compacted when it is at least
300mm thick.
When laying pipes in road and railway areas,
instructions from the relevant authorities must be
observed.
The degree of compaction must be at least 90-95%
Proctor, if not otherwise stated in the contractor’s plan.
When removing supporting structures (such as sheet
piles or trench boxes), take care not to endanger work
safety or trench wall stability, loosen the compacted
backfill or move the pipe out of position.
Backfilling
The term “primary” refers to the material to be used
around the pipe above the native soil trench bottom or
the bedding. Primary backfill extends to at least
300mm above the pipe crown and/or as specified by
local standards.
The primary backfill material must meet the same
requirements as the bedding materials. Backfilling
should extend over the entire trench width. The
primary backfill material may not be dropped on top of
the pipe in such a way that the pipe is moved or
damaged; it must be placed as evenly as possible on
both sides of the pipe and packed under the pipe
haunches and on the sides.
The final backfill material may be compactable as-dug
material, but must in any case be free from stones
larger than 300mm. Where necessary, and especially
in traffic areas, compaction is carried out in several
300mm layers to compaction levels corresponding to
those of the primary backfill. On the surface, use
backfill material that matches the surrounding surface.
Structural Design
In general, structural design of a pipeline by analytical
or numerical methods is not needed. Any calculated
prediction of the pipe behaviour depends greatly on
the degree of correspondence between the calculation
assumptions and the actual installation; it is therefore
important to base the former on reliable input values
obtained from extensive soil surveys and monitoring
of the installation.
However, when structural design is required, e.g. in
cases where no other information exists, a method as
defined in EN 1295-1 should be used. As far as input
values for the pipes are required, the following values
are recommended:
In the first stage, the material is spread in the trench
with a spade or by other means and compacted so
that the pipe is not moved or damaged. If necessary,
the pipe may be pressed down or anchored or filled
with water to prevent it from lifting during compaction.
The backfill material is compacted in layers of
150-300mm.
32
Material
PE
Remarks
E-modulus (Mpa) 1000
Modulus of elasticity
(-)
0.4
Poisson’s ratio
-5
(mm/mm.K)
13 x 10 Lin. expansion coefficient
Pressure Testing
Pressure Testing on
Non-Pressure Pipes on
Site
Method
a.
b.
Testing
In the acceptance inspection, if required, compliance
of the installation work with the planning documents is
verified. As part of the final inspection, tightness can
be tested. Tightness testing of Weholite pipes is
performed with reference to national requirements, but
normally according to the following alternative methods:
SABS 1200 LD 1982 Standard specification for civil
engineering construction; LD sewers SFS 3113.
Leak testing on pipelines is conducted either with air
or water.
ℓ = litre of added water
m = length of piping in metres
h = hour
The value thus obtained and the inside diameter of
the pipe are inserted in the diagram below. All
readings below the line are acceptable.
For further information, see Standard SFS 3113.
Principle
(Summary of the Finnish standards SFS 3113)
A delimited section of pipe is filled with water and
subjected to a certain overpressure. The tightness is
determined in the final stage of the test by determining
the quantity of additional water needed to maintain the
pressure.
The necessary overpressure in the pipe depends on
the level of the ground water in relation to the level of
the piping to be tested. The difference between these
two levels is marked with “a”. The overpressure is
derived from the following graph:
l/m h
2,6
2,4
Difference
between the
subsoil water and
the pipe (m)
a<0
0<a<5
0.5<a<1.0
1.0<a<1.5
1.5<a<2.0
2.0<a<2.5
2.5<a<3.0
3.0<a<3.5
3.5<a<4.0
4.5<a<5.0
Test overpressure Pe1
kPa
Bar
10.0
15.5
21.0
26.5
32.0
37.5
48.5
54.0
59.5
65.5
0.1
0.155
0.21
0.265
0.32
0.375
0.485
0.540
0.60
0.65
2,2
2,0
1,8
1,6
1,4
1,2
1,0
duration of the test
Volume of the added water per length unit and the
c.
Fill a pipe section with water to overpressure P.
Check that all seals are watertight and hold the
pressure for 10 minutes.
The overpressure is maintained at the level P
during half an hour by adding water when
necessary. Measure the volume of water added
during three 6-minute intervals.
When the test is completed, the average volume
of the added water is calculated. This volume is
converted into functions of pipe length and time
(ℓ/mh),:
0,8
0,6
0,4
0,2
0
200
400
600
800
1 000
1 200
1 400
1 600
Inside diameter mm
33
Testing SABS 1200 LD Sewer 1982
General
All acceptance tests shall be carried out in the presence
of the engineer and at such times and in such manner
as the engineer may direct. Subject to the provision of
7.1.5, no pipe joint or fitting shall be covered until the
applicable tests given in 7.2 have been completed and
the engineer has:
a.
b.
given his written acknowledgement that the sewer
or the specified section of it has passed the said
test, and
authorised such covering.
The sewer or any section of it shall be inspected by the
contractor who, if he deems it ready to be tested, shall
advise the engineer of his intention to subject the sewer
or said section of it to the appropriate tests.
The sewer shall be tested in sections between manholes
or chambers, as applicable, the section being tested
must be isolated from other sections by means of
suitable plugs or stoppers that have been braced
adequately.
Notwithstanding any acknowledgement by the engineer
in terms of 7.1.2, after backfilling and compaction have
been completed, the engineer may order that the sewer
be retested to check that it has not been disturbed or
damaged during backfilling.
The engineer may order one of the following to be
carried out on the sewer or any section of it:
a.
b.
c.
1. an air test on pipes (other than concrete pipes)
of all sizes; or
2. in the case of pipes (other than concrete) of
diameter up to 600mm, an air test followed by a
water test;
a water test in the case of pipes of diameter up to
750mm;
a visual internal inspection in the case of pipes of
diameter greater than 750mm.
The contractor shall provide all labour and apparatus
(including expansive plugs and flexible bag stoppers)
that may be required for carrying out the tests.
All test results shall be recorded in the manner directed,
whether or not the pipeline or section of pipeline has
passed the test.
34
Tests and
Acceptance/Rejection
Criteria
Air Test
Pipelines above the water table:
An approved air testing machine shall be used to raise
the gauge pressure in the section of the pipeline
under test first to 3.75 kPa. After a 2 min stabilisation
period, the pressure shall be reduced to 2.5 kPa. The
machine shall then be switched off and the time taken
for the pressure to drop from 2,5 kPa to 1.25 kPa shall
be determined. The time taken shall be at least the
applicable of the following values:
Nominal diameter
of pipe (mm)
Minimum time (min)
taken for pressure to
drop from 2.5 kPa to
1.25 kPa
100
150
200
225
250
300
375
450
600
750
2.0
3.0
4.0
4.2
4.5
6.0
7.5
9.0
12.0
15.0
Pipelines below the water table:
An approved air testing machine shall be used to raise
the gauge pressure in the section of the pipeline
under test to 2.5 kPa above the static water pressure.
After this pressure has been attained and the machine
stopped, any change in pressure shall be noted.
There shall be no discernible loss for a period of at
least 5 min.
Water Test
The section of the pipeline under test and, unless
otherwise specified, the manhole chamber at the
upper end of the said section shall be filled with water
to such a depth that every portion of the pipeline is
subjected to a pressure of not less than 12 kPa and
not more than 60 kPa.
During the test, there shall be no discernible leakage
of water. An appropriate period, which shall be at least
10 min, shall be allowed for initial absorption, and the
loss of water over the next 30 min shall be noted.
The amount lost shall not exceed the applicable of the
following rates per 100m of pipeline per hour:
Nominal diameter
of pipe (mm)
100
150
200
225
250
300
375
450
600
750
Minimum time (min)
taken for pressure to
drop from 2.5 kPa to
1.25 kPa
6.0
9.0
12.0
13.5
15.0
18.0
22.5
27.0
36.0
45.0
Should any section of the pipeline fail to pass the
water test, a retest will be permitted and, in such case,
acceptance or rejection of the section shall be
determined on the result of the retest.
Rejection
In the case of AC, vitrified clay and pitch-impregnated
fibre pipes, failure under the air test will be deemed to
be cause for rejection. After such rejection, the
contractor may apply a water test to locate the source
of failure, rectify the pipeline, and re-apply the air test.
In the case of reinforced concrete, failure under the
water test will be deemed to be cause for rejection.
Test of Connecting Sewers
Each connecting sewer shall be tested between its
upper end and the junction at the main sewer. The
upper end of the connection shall be kept securely
closed with expanding plugs during the test. Where
practicable, the contractor may test the main and
connections simultaneously if he so wishes. On
completion of the test, the upper end of the
connection shall be permanently sealed as directed by
means of a plug stopper suitable for the type of pipe.
Test of Rising Mains
After a rising main has been laid and the joints
completed, the main shall be slowly charged with
water, so that all air is expelled, and then tested in
accordance with Subclause 7.3 of SABS 1200 L.
Watertightness of Manholes
Where so required in terms of the project
specification, manholes shall be tested for
watertightness separately from the pipeline.
35
Support Spacing and Buoyancy
Support Spacing
With installations above ground, the maximum
support spacing can be determined according to the
figure on the left hand side.
Support spacing
- sag 10mm/10 years
- liquid density 1000kg/m3
5
+ 20 °C
4
+ 40 °C
3
+ 60 °C
2
1400
1200
1000
800
600
400
200
1
0
Support spacing, m
6
Pipe ID, mm
Buoyancy
When installing pipes under the ground water level, the buoyancy of the pipe must be taken into consideration.
Where necessary, the natural uplift of the pipe should be counteracted. This can be designed case by case. Please
do not hesitate to contact your nearest Marley branch for technical information.
36
DN/ID
mm
dn
mm
Pipe Empty
Profile Empty
kN/m
Pipe Full
Profile Empty
kN/m
Pipe Full
Profile Full
N/m
360
400
500
600
700
800
1000
1200
1400
1500
1600
1800
2000
2200
400
450
560
675
790
900
1125
1350
1575
1680
1792
2016
2240
2464
1.23
1.52
2.38
3.43
4.66
6.09
8.97
13.70
18.65
21.41
24.36
30.83
38.06
46.04
0.24
0.29
0.45
0.65
0.89
1.16
1.27
2.61
3.55
4.08
4.64
5.87
7.25
8.78
10
10
10
10
20
20
30
40
50
60
70
90
110
130
General Notes and Limitations
General Notes
This Structured Wall Pipe (Weholite) Manual has been produced as a guide for engineers, purchasing officers and
contractors to cover the application and use of Weholite pipes and fittings.
This document will be reviewed from time to time in order to keep it fully relevant to modern water and wastewater
industry practice. Any comments and suggestions regarding its content will be appreciated.
The information contained herein is intended as a guide, and its accuracy and applicability is not guaranteed.
Marley Pipe Systems assumes no obligation or liability in respect of this information. All tables and statements may
be considered as recommendations, but do not constitute a warranty. Users of our products should carry out their
own tests to determine the suitability of each product for their particular purposes. Marley’s liability for defective
products is limited to the replacement, without charge, of any product found to be defective in line with their
standard condition of tender and sale. In no circumstances shall it be responsible for any damages beyond the
price of the products, and in no event shall it be liable for consequential damages.
Limitation of Liability
Whilst the information, opinions, advice and recommendations contained in this publication have been prepared
with proper care, they are offered only in order to provide useful information to those interested in technical matters
associated with pipeline design, selection and installation.
The information contained herein is not intended to be an exhaustive statement of all relevant data, as the
successful installation in each case may depend on numerous factors beyond our control. Marley Pipe Systems
accepts no responsibility for or in connection with the quality or standard of any pipeline or installation or its
suitability for any purpose when installed.
All conditions, warranties, obligations and liabilities of any kind which are or may be implied or imposed to the
contrary by any statute, rule or regulation or under common law and whether arising from the negligence of the
Company, its servants or otherwise, are hereby excluded except to the extent that the Company may be prevented
by any statute, rule or regulation from doing so.
37
Conversion Factors
Numerical values of SR corresponding to some standard
classification series.
SR (kN/m2 = kPa)
SR (MN/m2 = MPa)
SR ((psi) acc. ASTM 28)
Stiffness (kPa) SANS 1601
PVC (D/s = SDR)
PVC (ISO S-series)
PVC (s/Dm%)
PVC (PN bar)
HDPE 63 (PN bar = s/Dm%)
HDPE100 SDR
2
0.002
16
100
51
25
2
4
3.2
33
4
0.004
32
200
41
20
2.5
5
4
26
8
0.008
64
400
33
16
3
6
5
21
16
0.016
128
800
26
12.5
4
8
6.3
17
32
0.032
256
1600
21
10
5
10
8
13.6
For GRP pipes, SR is also used for pipe classification but the unit is commonly N/m2 (Pa) according to ISO, e.g.
1000 times larger than the standard values for thermoplastics. A common series is 2500, 5000, 10000 and
20000 N/m2.
In the USA, the ring stiffness concept is also used, but is then defined according to ASTM and expressed in psi.
The numerical values in psi in the above table are 8 times larger than those given above in kN/m2, e.g. 16, 32, 64,
etc. A common pipe stiffness series used in the USA for GRP is 18, 36 and 72 psi.
Volume (litres, cubic feet, gallons)
Gallons (US) Gallons (lmp)
Volume (m , cubic yards, gallons)
3
Litre (dm3)
Cubic Feet
1
0.0353147
0.264171
28.3168
1
7.480456
6.2288
3.78542
0.133682
1
0.83268
4.54609
0.160544
1.20094
1
0.00454609
0.219969
Volume (m , acre feet, morgen feet, gallons)
3
1
1.30795
264.171
219.969
0.76455
1
201,974
6.2288168.178
0.003785
0.00495115
1
0.83268
0.0059461
1.20094
1
ft3/second
Gal (lmp/min)
Flow
m3 (kilolitre)
Acre Feet
1
0.00081071
0.000383038
219.969
1
0.001
0.0353147
13.19814
1233.48
1
0.47247
271328
1000
1
35.3147
13198.14
2.11654
1
574275
28.3168
0.0283168
1
373.73
1
0.0757682
75.7682 x 106
0.002676
1
2610.71
0.00454609
38
Morgen Feet Gallons (lmp)
Cubic Metres Cubic Yards Gallons (US) Gallons (lmp)
0.000003686 0.0000017413
Litre/second m3 /second
Conversion Factors
Force
Newton
Kilogram Force
Metric Ton
- Force
Pound
- Force
Ton
(2000lb Force)
Ton (2240 lb)
Force
1
9.80665
9806.65
4.44822
8896.44
9964.02
0.101972
1
1000
0.453592
907.184
1016.05
0.101972 x 103
103
1
0.453592 x 103
0.907184
1.01605
0.274809
2.20462
2204.62
1
2000
2240
0.112405 x 105
1.10231 x 103
1.10231 x 103
0.0005
1
1.120
0.10036 x 103
0.984206 x 103
0.984296
0.446429 x 103
0.892858
1
Pressure
Pascal
(Newton/m2)
Bar
1
10-5
105
98.0665 x 10
3
6894.76
Kilogram Pound Force Metre head
per inch2
of water
Force/cm2
Foot head Ton (2000lb) Ton (2240lb)
of water
force/in2
force/in2
0.101972 x 10-4 0.145038 x 10-3 0.101972 x 10-3 0.33455 x 10-5 0.072519 x 10-6 0.064749 x 10-6
1
1.01972
14.5038
10.1972
33.455
0.0072519
0.006479
0.980665
1
14.2233
10
32.8084
7.11167 x 10
0.0005
-3
6.34971 x 10-3
0.446429 x 10-3
0.0689476
0.070307
1
0.70307
2.306727
3
0.0980665
0.1
1.42233
1
3.28084
0.711167 x 10 0.634971 x 10-3
2.98898 x 103
0.0298898
0.03048
0.433515
0.3048
1
0.21676 x 10-3 0.193533 x 10-3
13.7895 x 106
137.895
140.614
2000
1.40614 x 103 4.61332 x 103
1
0.892858
15.4443 x 106
154.433
157.488
2240
1.57488 x 103 5.16692 x 103
1.120
1
9.80665 x 10
-3
39
Notes:
40
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V a l u e
P a r t n e r
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Tel: +27 11 739-8600 | Fax: +27 11 739-8680
1 Piet Pretorius Street, Rosslyn, Pretoria
Tel: 0861 MARLEY (627539)
For additional information on the latest product offerings from Marley
Pipe Systems visit www.marleypipesystems.co.za
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