ISO 7432:2021

INTERNATIONAL ISO
STANDARD 7432
Third edition
Glass-reinforced thermosetting
plastics (GRP) pipes and fittings —
Test methods to prove the design
of locked socket-and-spigot joints,
including double-socket joints, with
elastomeric seals
Tubes et raccords en plastiques thermodurcissables renforcés de
verre (PRV) — Méthodes d'essai pour confirmer la conception des
assemblages mâle-femelle verrouillés, y compris ceux à double
emboîture avec joints d'étanchéité en élastomère
PROOF/ÉPREUVE
Reference number
ISO 7432:2021(E)
©
ISO 2021

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ISO 7432:2021(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2021
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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Published in Switzerland
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ISO 7432:2021(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
5 Apparatus . 3
5.1 End-sealing devices. 3
5.2 Supports . 3
5.3 Source of hydrostatic pressure . 3
5.4 Pressure gauges. 3
5.5 Vacuum pump . 3
5.6 Means of applying and measuring the required deformation and bending forces . 3
6 Test pieces . 4
6.1 General . 4
6.2 Test arrangement for tests detailed in 9.2 and 9.6 . 4
6.3 Test arrangement for tests detailed in 9.3 and 9.4 . 4
6.4 Test arrangement for tests detailed in 9.5 . 5
6.5 Number of test pieces . 7
7 Conditioning . 7
8 Test temperature . 7
9 Procedure. 7
9.1 General . 7
9.2 Negative pressure . 8
9.3 Deformation with internal pressure and end thrust . 9
9.4 Deformation with cyclic pressure and end thrust . 9
9.5 Bending with cyclic pressure and end thrust . 9
9.5.1 Introductory notes . 9
9.5.2 Method A .10
9.5.3 Method B .10
9.6 Internal pressure and end thrust .11
10 Test report .11
Annex A (normative) Calculation of the additional force, F , and limiting deflection, Δ, used
A
in 9.5, Method A .13
Annex B (normative) Calculation of the bending load, F , used in the bending test in 9.5,
B
Method B .14
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ISO 7432:2021(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.
This third edition cancels and replaces the second edition (ISO 7432:2018), which has been technically
revised.
The main changes compared to the previous edition are as follows:
— addition of the bending test (Method A), which was already included in ISO 7432:2002.
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 7432:2021(E)

Introduction
In a pipework system, pipes and fittings of different nominal pressures and nominal stiffnesses may
be used. A joint may be made between pipes and/or fittings and should be designed such that its
performance is equal to or better than the requirements for the pipeline, but not necessarily for the
components being joined.
The requirements for the assembly of the joint are not included in this document, but they should be in
accordance with the manufacturer’s recommendations.
Material-dependent parameters and/or performance requirements are stated in the relevant standard.
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INTERNATIONAL STANDARD ISO 7432:2021(E)
Glass-reinforced thermosetting plastics (GRP) pipes and
fittings — Test methods to prove the design of locked
socket-and-spigot joints, including double-socket joints,
with elastomeric seals
1 Scope
This document specifies methods of test for joints with a locked socket and spigot, including double-
socket joints, and with elastomeric seals, for buried and above-ground glass-reinforced thermosetting
plastics (GRP) piping systems.
It covers methods of testing for leaktightness and resistance to damage of the joint only, when subjected to
specified combinations of angular movement, compression (deformation) perpendicular to the pipe axis
and internal pressure. It assumes that the joint will be exposed to the effects of hydrostatic end thrust.
The tests detailed in 9.2, 9.3, 9.4 and 9.6 are applicable to joints with a locked socket and spigot,
including double-socket joints, and with elastomeric seals intended to be used in buried or above-
ground applications.
The bending tests detailed in 9.5 can be used to prove the design where joints are either intended to be
used in buried applications or are intended to be used in particular above-ground situations, where the
tests can be considered appropriate.
With the exception of the procedure detailed in 9.5, these test procedures are applicable to joints
for pipes and fittings of all nominal sizes. The tests detailed in 9.5 are applicable to joints for pipes
and fittings up to and including DN 600. The tests are applicable for evaluating joints intended for
applications conveying liquids at temperatures specified in the referring standards.
The test procedures in this document are damaging to the test piece, which will not be suitable for
reuse after these tests. The test procedure is intended for type testing purposes.
This document is applicable only to the joint and specifies methods of testing to prove its design.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
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/
3.1
pressure
hydrostatic gauge pressure
Note 1 to entry: Expressed in bar.
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ISO 7432:2021(E)

3.2
bending
beam bending in the pipe and joint configuration as a result of a transverse force on the joint
3.3
deformation
pipe deformation in the coupling as a result of a vertical force on the pipe and a supported coupling
causing a step between the two pipe spigots at the loading position
4 Principle
A test piece comprising two pieces of pipe jointed together, by incorporation of a socket or inclusion of a
double-socket coupler, is subjected to specified load conditions, including combinations of bending and
deformation. In each specified combination the test piece is subjected to a series of test pressures for
specified periods of time, including an internal sub-atmospheric test pressure. This also simulates an
external positive pressure.
The procedure includes prolonged static tests at elevated pressures and cyclic testing to prove the
structural design of the joint.
A joint is subjected to a specified internal negative pressure. This also simulates an external positive
pressure.
Two methods are specified for the arrangement in 9.5, Method A and Method B. Method A is the default
method. Method B shall be applied on request by the purchaser.
When under pressure, the joint is monitored for leakage. After each test condition (see Table 1) the joint
is inspected for signs of damage.
In addition, a test at elevated positive static pressure is conducted to prove the structural design of the
joint (see Table 1 and 9.6).
NOTE The only reason for testing the joint for resistance to negative pressure is to ensure adequate safety
against infiltration of pollutants through the joint into the fluid carried in the piping system. Under the test
conditions used, pipes with low stiffness can require support to prevent buckling.
It is assumed that the following test parameters are set by the standard making reference to this
document:
— the nominal size of the components to be connected by the joint;
— the pressure class of the components;
— the total effective length, L, of the test piece;
— the number of test pieces;
— if applicable, the conditioning to be applied;
— the test temperature;
— the sequence of testing, if appropriate;
— the test configuration;
— the deformation and bending forces, F or F ;
A B
— the permissible change in negative pressure.
In all of these arrangements, a joint of the same size and design shall be used. The same test piece may
be used for more than one test procedure, providing it is undamaged and of sufficient size to enable the
test conditions to be achieved.
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ISO 7432:2021(E)

5 Apparatus
5.1 End-sealing devices
The end sealing devices shall be of sizes and types appropriate to the components under test. The end-
sealing devices shall be securely fixed to the pipes to transmit the end thrust loads to the pipes.
5.2 Supports
5.2.1 Straps or cradles, for use as follows:
a) a support R of sufficient width, typically 150 mm (item 6 in Figure 2), positioned at least 500 mm
from the spigot end of the pipe at the point of balance to provide support during testing with
deformation (see 9.3 and 9.4);
b) a strap or cradle (100 ± 5) mm wide (item 7 in Figure 2), supporting at least a 120° arc of the
socket, as required for deformation testing (see 9.3 and 9.4);
c) a strap or cradle (100 ± 5) mm wide, supporting an arc up to 180° of the pipe barrel, positioned
adjacent to the end of the joint being tested (item 5 in Figure 2) and through which the force F1
necessary for deformation testing (see 9.3 and 9.4) can be applied;
d) a strap or cradle (100 ± 5) mm wide, supporting an arc up to 180° of the pipe barrel, positioned in
the middle of the joint being tested (item 6 in Figure 3, item 5 in Figure 4) and through which the
force, F or F , necessary for the bending test (see 9.5) can be applied;
A B
e) supports of sufficient width, typically 150 mm, to carry the pipe components of the test piece
(item 3 in Figure 2) and designed in such a way that they allow deformation to occur.
The straps or cradles shall not have a detrimental effect on the test piece, e.g. by applying point loads.
5.2.2 Special supports
Special supports shall be used if necessary to prevent buckling of the pipe barrel during deformation
(see 9.3 and 9.4) or negative pressure (9.2) testing. Such supports shall be positioned in such a way that
they do not affect the force, F , applied to the joint or the joint’s response to such a load.
1
5.3 Source of hydrostatic pressure
The source of hydrostatic pressure shall be capable of applying the required pressures including, as
necessary, pressure cycle controls.
5.4 Pressure gauges
Pressure gauges shall be capable of measuring the positive and negative pressures. The gauges shall be
calibrated to an accuracy of ±2 % of the value to be measured.
5.5 Vacuum pump
The vacuum pump shall be capable of producing the required negative gauge pressure (see 9.2).
5.6 Means of applying and measuring the required deformation and bending forces
The means of applying the required deformation forces F (see 9.3 and 9.4) and bending forces F (see
1 A
9.5.2 and Annex A) or F (see 9.5.3 and Annex B) shall be calibrated to an accuracy of ±5 % of the value
B
to be measured.
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ISO 7432:2021(E)

6 Test pieces
6.1 General
The test piece shall comprise an assembly of two pieces of pipe of the size and pressure class, as
specified in the referring st
...