ISO/PRF TS 10986

Plastics piping systems -- Glass-reinforced thermosetting plastics (GRP) pipes -- System design of above ground pipe and joint installations without end thrust

Systèmes de canalisations en plastiques -- Tubes en plastiques thermodurcissables renforcés de verre (PRV) -- Conception de système d'installations de tubes et d'assemblages en aérien sans poussée d'extrémité

General Information

• Status: Published
• ICS: 23.040.20 - Plastics pipes
• Technical Committee: ISO/TC 138/SC 6 - Reinforced plastics pipes and fittings for all applications
• Drafting Committee: ISO/TC 138/SC 6/WG 5 - Installation

Standards Content (sample)

TECHNICAL ISO/TS
SPECIFICATION 10986
First edition
Plastics piping systems — Glass-
reinforced thermosetting plastics
(GRP) pipes — System design of above
ground pipe and joint installations
without end thrust
Systèmes de canalisations en plastiques — Tubes en plastiques
thermodurcissables renforcés de verre (PRV) — Conception de
système d'installations de tubes et d'assemblages en aérien sans
poussée d'extrémité
PROOF/ÉPREUVE
Reference number
ISO/TS 10986:2021(E)
ISO 2021
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ISO/TS 10986:2021(E)
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© ISO 2021

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Published in Switzerland
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ISO/TS 10986:2021(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Angular deflection of joints ....................................................................................................................................................................... 1

4.1 General ........................................................................................................................................................................................................... 1

4.2 Effects of loads on joint angular deflection .................................................................................................................... 3

4.3 Measuring deflections ....................................................................................................................................................................... 3

4.4 Checking the installed joint .......................................................................................................................................................... 4

4.4.1 General...................................................................................................................................................................................... 4

4.4.2 Coupling-to-pipe position ........................................................................................................................................ 4

4.4.3 Joint misalignment ......................................................................................................................................................... 5

4.4.4 Gap between pipe ends .............................................................................................................................................. 5

4.4.5 Adjusting joints ................................................................................................................................................................. 6

5 Installation of above ground pipes .................................................................................................................................................... 6

5.1 General ........................................................................................................................................................................................................... 6

5.2 Supporting of pipes ............................................................................................................................................................................. 7

5.2.1 General...................................................................................................................................................................................... 7

5.2.2 Support design ................................................................................................................................................................... 9

5.2.3 Loads on supports .......................................................................................................................................................10

5.3 Anchor design .......................................................................................................................................................................................11

5.4 Guide design ...........................................................................................................................................................................................11

5.5 Maximum support spacing ........................................................................................................................................................14

5.5.1 General...................................................................................................................................................................................14

5.5.2 Perpendicular forces .................................................................................................................................................15

5.5.3 Forces due to angular deviation ......................................................................................................................15

5.5.4 Axial forces .........................................................................................................................................................................15

5.5.5 Maximum total axial force ....................................................................................................................................17

5.5.6 Deformations and bending moments for pipes resting on two supports ....................18

5.5.7 Deformations and bending moments for pipes resting on multiple supports ........20

5.5.8 Load cases and combinations of long- and short-term loads.................................................23

5.5.9 Checking of stresses and deformations .....................................................................................................24

Annex A (informative) Pipeline pressure testing and inspection .......................................................................................27

Annex B (informative) Recording above ground joint deflection data ..........................................................................34

Bibliography .............................................................................................................................................................................................................................37

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ISO/TS 10986:2021(E)
Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards

bodies (ISO member bodies). The work of preparing International Standards is normally carried out

through ISO technical committees. Each member body interested in a subject for which a technical

committee has been established has the right to be represented on that committee. International

organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of

electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are

described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the

different types of ISO documents should be noted. This document was drafted in accordance with the

editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of

any patent rights identified during the development of the document will be in the Introduction and/or

on the ISO list of patent declarations received (see www .iso .org/ patents).

Any trade name used in this document is information given for the convenience of users and does not

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

expressions related to conformity assessment, as well as information about ISO's adherence to the

World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/

iso/ foreword .html.

This document was prepared by Technical Committee ISO/TC 138, Plastics pipes, fittings and valves for

the transport of fluids, Subcommittee SC 6, Reinforced plastics pipes and fittings for all applications.

Any feedback or questions on this document should be directed to the user’s national standards body. A

complete listing of these bodies can be found at www .iso .org/ members .html.
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ISO/TS 10986:2021(E)
Introduction

While pipes manufactured according to ISO 23856 are typically utilized in buried installations, there

are circumstances where installing above ground is the preferred practice. These can include terrain

not suitable for burial (e.g. rock), road or river crossings, unsuitable soils and installation on steep

slopes.

For information on subjects such as shipping, handling, inspecting, rigid connections, thrust restraint

and joining pipes, refer to ISO/TS 10465-1 which addresses the buried installation of GRP pipes. The

guidelines and information on these subjects are also applicable to pipes used above ground. The

information in this document is intended to supplement ISO/TS 10465-1 with practices and guidelines

specific to above ground installation.
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TECHNICAL SPECIFICATION ISO/TS 10986:2021(E)
Plastics piping systems — Glass-reinforced thermosetting
plastics (GRP) pipes — System design of above ground pipe
and joint installations without end thrust
1 Scope

This document addresses the system design of pipe and joints of above ground installations without

end-thrust as specified in systems standard ISO 23856. It is directed to pipelines with a minimum

stiffness of SN 5000 laid in a straight line between thrust blocks. It is based on the safety concepts

described in ISO TS 20656-1, with consequence class 2 (CC2) as default. For other consequence classes,

certain details specified in this document can need to be modified. This document is directed to double

bell coupling. However, much of the information can be adapted and utilized for other flexible joints

systems.

This document does not cover fittings nor detailled engineering work like thrust blocks, support and

anchor designs.

As installation is not included in the scope of this document and to assist system design, Annex A

provides a pressure testing and inspection procedure. However, to ensure the use of clearly defined

field test data in system design, Annex A can be used normatively by agreement between purchaser and

supplier. An example of recording above ground joint deflection data is given in Annex B.

2 Normative references
There are no normative references in this document.
3 Terms and definitions
No terms and definitions are listed in this document.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
4 Angular deflection of joints
4.1 General

The angular deflection at flexible joints shall be controlled to avoid excessive loads on the pipeline

and its supporting structures. Above ground installations do not benefit from the stabilizing support

that is given by the soil in buried installations, and they are therefore more susceptible to problems

of joint misalignment. For this reason, control and measurement of joint angular deflection is of

great importantance. It is necessary to limit angular deflections to lower values than those normally

permitted for buried applications.

There are two types of deflection to consider: pipe-to-pipe angular deflection and coupling-to-pipe

deflection, as shown in Figure 1. Both need to be considered as coupling-to-pipe angular deflection can

be larger than the pipe-to-pipe angular deflection.
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ISO/TS 10986:2021(E)
Key
1 coupling-to-pipe angular deflection
2 pipe-to-pipe angular deflection
Figure 1 — "Pipe-to-pipe" and "coupling-to-pipe" deflection, example 1

For some designs of double socket joint the pipe can only move on one side of the coupling. In that case,

the pipe-to-pipe angular deflection is equal to the coupling-to-pipe angular deflection on one side (see

Figure 2). The manufacturer should advise which case will occur with their design of joint.

Key
1 pipe-to-pipe = pipe-to-coupling angular deflection
Figure 2 — "Pipe-to-pipe" and "coupling-to-pipe" deflection, example 2
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ISO/TS 10986:2021(E)
4.2 Effects of loads on joint angular deflection

The angular deflection is influenced by several factors in addition to the initial pipe installation, such as

load-induced pipe deflections and support settlement.

Pipe deflections after inital installation are caused by forces produced by the weight of fluid in the pipe,

external loads and pressure within the pipeline. These forces can produce significant pipe-to-coupling

deflections which, if acting in a similar plane to the initial installation deflection, can result in the total

deflection at the coupling exceeding the allowable limit. An example of this effect is shown in Figure A.3.

The initial pipe angular deflection therefore should be limited to allow for this effect to ensure that the

total deflection does not exceed the maximum coupling deflection specification.
4.3 Measuring deflections

The coupling-to-pipe angular deflection is measured as an angular offset, see Figure 3.

Key
L coupling offset (left L
off,l off,l,min
minimum coupling offset (left pipe)
pipe) = L − L
off,l,max off,l,min
L coupling offset (right L
off,r off,l,max
maximum coupling offset (left pipe)
pipe) = L − L
off,r,max off,r,min
L minimum coupling offset (right pipe)
off,r,min
L maximum coupling offset (right pipe)
off,r,max
Figure 3 — Measurements for determining the angular offset
Coupling offsets L and L should be measured as follows:
off,l off,r

Find the maximum and the minimum distance between the homeline and the face of the coupling along

the circumference of the pipe. Subtract the minimum found value from the maximum found value.

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ISO/TS 10986:2021(E)

The total pipe-to-pipe offset, L , is calculated by additioning L and L , see Formula (1):

off,tot off,l off,r
LL=+L (1)
offt, ot off,loff,r

The total pipe-to.pipe offset, L , shall be smaller or equal to the maximum allowable coupling offset

off,tot
L , see Formula (2):
off,max
LL≤ (2)
offt,,ot offmax
with Formula (3):
α π
max
L =DN∙ (3)
offm, ax
180

NOTE Formula (1) and Formula (2) are only valid for conditions given in Figure 3, but not for conditions

seen in Figure 9, where the coupling-to-pipe angular deflection is larger than the pipe-to-pipe angular deflection.

However, the same logic applies.

The maximum pipe-to-pipe offset for empty pipes installed in straight alignment is shown in Table 1.

Table 1 — Maximum pipe-to-pipe offset for pressure pipes installed in straight alignment

Pipe nominal size Declared allowable joint Maximum allowable Example
(pipe-to-pipe) installed angular deflection,
DN Maximum value
angular deflection, α , α, in degrees
max
(L +L ) in
off,l off,r
in degrees (not filled, no pressure)
≤ 500 3 1 500 9
500 < DN ≤ 900 2 2/3 900 10
900 < DN ≤ 1 800 1 1/3 1 800 10
> 1 800 0,5 1/6 3 600 10

In service, the following factors cause an increase in the angle, α, and as a result, L :

off,tot
— weight of water
— pressurizing
— creep in the pipe material.
See 5.5.9.3 for further details.
4.4 Checking the installed joint
4.4.1 General

The quality of the joint installation should be checked as soon as possible after assembly as correction

can be difficult when the coupling gaskets have settled. Information regarding forms that can be used

for recording the joint quality control is given in Annex B.

The installed joint should be checked at normal ambient temperatures. High or uneven pipe

temperatures as can be caused by direct sunlight, for example, affect the results of the checks.

4.4.2 Coupling-to-pipe position

It is important for the coupling to be located as centrally as possible between the two pipe ends in order

to avoid interference of the pipe end with the gasket or the pipe ends touching during operation.

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ISO/TS 10986:2021(E)
4.4.3 Joint misalignment

Maximum misalignment of pipe ends should not exceed the lesser of 0,5 % of pipe diameter or 3 mm.

The misalignment can be measured with two identical notched rulers pressed against the pipe at both

sides of the coupling, see Figure 4. If the depth of the machined spigot surface is different for the two

pipes, the measured misalignment should be corrected accordingly. For pipes 700 mm and larger the

misalignment can be measured with a ruler from the inside of the pipe, see Figure 4.

Key
1 rulers
2 joint misalignment
3 machined spigot surfaces (measure gaps between rulers and spigot surface)

NOTE On some pipes there is no machined spigot surface, either because it is not designed to have one or

because it is negligible because the pipe barrel OD is the correct spigot diameter.

Figure 4 — Misalignment
4.4.4 Gap between pipe ends

The gap between pipe ends is checked by measuring the distance between the homelines (see Figure 5).

The gap, d , is then calculated using Formulae (4) and (5):
dd=−2d (4)
g,minmin 1
dd=−2d (5)
g,maxmax 1
where
d is the minimum measured gap between pipe ends;
g,min
d is the maximum measured gap between pipe ends;
g,max
d is the minimum measured distance between homelines;
min
d is the maximum measured distance between homelines;
max
d is the distance from the pipe end to the homeline
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ISO/TS 10986:2021(E)

The engineer should decide what the value of the gap should be, based on maximum and minimum

allowable draw and installation and service conditions. These include at least increased rotation due to

weight of water and effects of pressure and creep, Poisson’s effect and temperature change.

The distance from the pipe end to the homeline, d , can be found in the pipe specifications or measured

prior to installation, see Figure 5.
Key
1 homeline d distance of homeline from end of pipe

d minimum measured distance between homelinesd minimum measured gap between pipe ends

min g,min
d maximum measured distance between d
max g,max
maximum measured gap between pipe ends
homelines
Figure 5 — Gap between pipe ends

For pipes 700 mm and larger the gap can be measured directly from the inside of the pipe.

4.4.5 Adjusting joints

The joint should be adjusted if any of the checks described in the preceding clauses fall outside the

specified limits. The necessary adjustments of coupling or pipe position should be made carefully,

avoiding concentrated loads or impact loads that can damage the pipe or the coupling.

5 Installation of above ground pipes
5.1 General

The designer of an above ground pipe installation should be aware of the forces that act on the pipe

system, particularly where high system pressures exist.

When a component in a pressurized pipeline has a change in cross-sectional area or alignment

direction, a resultant force is induced. All components such as bends, reducers, tees, wyes or valves

shall be anchored or restrained to withstand these loads. This is the case for above ground as well as

buried pipes.

In buried pipelines, adequate resistance to movements at joints in undeflected installations is generally

provided by the pipe embedment. Such resistance shall be provided at the supports of an above ground

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ISO/TS 10986:2021(E)

pipeline. Care shall be exercised to minimize misalignments and all components shall be properly

supported to ensure the stability of the pipeline.
5.2 Supporting of pipes
5.2.1 General

A range of joint designs are manufactured for which a variety of support configurations are

recommended. Generally, pipes are supported on either side of the joint, but some systems allow direct

support under the joint.

To minimize the loads induced in pipes and supports, the supports should not restrain longitudinal

expansion of the pipes. However, it is essential that the pipe movements be guided and controlled in

such a way that all pipe sections are stable and that acceptable longitudinal movement of the pipe in the

couplings is not exceeded.

As non-restrained couplings are flexible, it is very important for the stability of every pipe component

to be ensured by the supports. Each pipe should therefore be supported by at least two cradles and

anchored by a pipe anchor at one of these cradles, while the remaining cradles should be designed as

guides, allowing longitudinal expansion of the pipe but restraining lateral movements. With direct

support under the joints, the coupling clamp can act as anchor, see Figure 6 (1) and Figure 8.

For pipes supported in more than two cradles, the cradle closest to the middle of the pipe should be

used as an anchor.

The anchors should be located with regular spacing to ensure even distribution of longitudinal pipe

expansion on the joints. However, the maximum distance between two anchors shall not result in

exceeding the draw limits specified for the joint given in ISO 23856.
Figure 6 shows typical support arrangements for pipes.
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ISO/TS 10986:2021(E)
Key
1 one cradle A coupling with anchor, which acts as pipe anchor
2 two cradles B guide
3 multiple cradles C pipe anchor

a maximum distance from the centreline of the D coupling anchor, if necessary, see 5.4

joint to centreline of a support, see Table 2
b maximum distance between two pipe anchors,
depending on the limits specified for the joint
given in ISO 23856
Figure 6 — Typical support arrangements

Table 2 — Maximum distance from the centreline of the joint to centreline of a support, a

DN a
DN ≤ 500 max. 250 mm
600 ≤ DN ≤ 1 000 max. 0,5 × DN
DN > 1 000 max. 500 mm

When a pipe is supported on more than two supports, the pipe supports should be in straight alignment.

The maximum deviation from the straight alignment should not exceed 0,1 % of the span length, L .

This applies to all load conditions of the system.

It is important that support displacement does not exceed the maximum misalignment of pipe ends in

joints as specified in 4.4.3.
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ISO/TS 10986:2021(E)

The pipes shall be supported adjacent to the joints, or directly under the joints, to ensure the stability

of the couplings.
5.2.2 Support design

Any excessive point or line loading should be avoided when pipes are installed above ground. Above

ground pipes should therefore be supported in cradles. Typically, the cradles are made from concrete

or steel, with a supporting angle of 150°. A smaller angle (but never smaller than 120°) or a larger angle

(but never larger than 180°) may be used, if it can be demonstrated that it will not cause excessive local

stresses.

The diameter of the finished cradle, with cradle liners, should be 0,5 % larger than the outer diameter

of the non-pressurized pipe. The cradles should have a minimum width of:
— 150 mm for all pipes with DN ≤ 1 000 mm,
— 200 mm for pipes with 1 000 mm < DN ≤ 2 000 mm, and
— 250 mm for pipes with DN > 2 000 mm.
See Figure 7.

Cover the inside of the cradles with a 5 mm thick cradle liner to avoid direct contact between pipe and

cradle. Liners should be made from materials that are resistant to the actual environment. High friction

liners should be applied at anchors while low friction liners should be applied at guides. See 5.3 and 5.4.

Figure 7 shows the cradle design for support under the pipe barrel.
Key
1 cradle liner, minimum thickness 5 mm 2 cradle width
Figure 7 — Typical cradle design for support under the pipe barrel
Figure 8 shows the cradle design for support under the coupling.
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ISO/TS 10986:2021(E)
Key
1 anchor strap also lined 3 anchor strap width, equal to 30 % of L
2 cradle liner 25 mm larger than cradle 4 cradle width, equal to 90 % of L
L coupling length
Figure 8 — Typical cradle design for support under the coupling
5.2.3 Loads on supports
The supports should be rigid and designed to withstand the loads caused by:
— external and environmental loads,
— weight of pipe and fluid,
— reaction forces caused by internal pressure,

— friction induced in couplings and against guides in case of temperature and/or pressure variations.

— head loss in pipe.

It is the responsibility of the owner's engineer to determine the actual design loads for the supports.

NOTE The reaction forces, caused by the weight of water, act perpendicular to the pipe. For pipe installations

on steep slopes this results in a significant horizontal load component acting on the pipe foundations. A common

error is to regard the reaction from water as vertical since it is a gravitational force.

Table 3 provides approximate axial forces that should be considered in the design of support cradles.

These loads result from contraction and elongation of pipes during operation and frictional resistance

in the gasketed joint.

Table 3 assumes simultaneous expansions and contractions of the neighbouring pipes. If non-

simultaneous expansions and contractions can be expected, contact the pipe supplier for adequate

axial forces.

Frictional force between pipe and guide should be determined based on total compression between

pipe and cradle and the frictional coefficient between the pipe material and the cradle liner.

For the cradle liners suggested in 5.4, the frictional coefficient can be assumed to be 0,3.

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ISO/TS 10986:2021(E)

Table 3 — SN 5 000 pipes — Typical axial loads due to pipe expansion/contraction and friction

at joints in kN
DN PN 6 PN 10 PN 16
≤ 300 5 6 7
350 6 6 8
400 6 7 8
450 6 7 9
500 7 8 10
600 8 9 11
700 8 10 12
800 9 11 14
900 10 12 15
1 000 11 13 16
1 200 12 15 19
1 400 14 17 21
1 600 15 19 24
1 800 17 21 27
2 000 18 23 29
2 200 20 25 32
2 400 22 27 35
2 600 23 29 37
2 800 25 31 40
3 000 26 33 43
3 200 28 35 45
3 400 30 37 48
3 600 31 39 51
3 800 33 41 53
4 000 34 43 56

NOTE These typical values result from experience and depend on sealing type used. For

exact figures, consult the manufacturer.
5.3 Anchor design

The function of the anchor support is to prevent the pipe from moving in the longitudinal and vertical

direction. It also needs to be able to transfer the longitudial loads (see 5.2.3) acting on the pipe to the

fixed supports.

There are several ways to design the anchor, such as clamping or using bonded saddles.

When clamping is used, the designer needs to be aware that GRP pipes have higher design strain and

can have higher coefficient of thermal expansion than steel. The anchor shall therefore be designed

to compensate for these differences. It shall be designed to give sufficient strap tension at low

temperatures without overloading the strap or the pipe in situations involving high temperatur

...