ISO/PRF 7432

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)
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© ISO 2021

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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

in 9.5, Method A ..................................................................................................................................................................................................13

Annex B (normative) Calculation of the bending load, F , used in the bending test in 9.5,

Method B ....................................................................................................................................................................................................................14

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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

— 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

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

The requirements for the assembly of the joint are not included in this document, but they should be in

Material-dependent parameters and/or performance requirements are stated in the relevant standard.

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

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-

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

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.

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

beam bending in the pipe and joint configuration as a result of a transverse force on the joint

pipe deformation in the coupling as a result of a vertical force on the pipe and a supported coupling

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

The procedure includes prolonged static tests at elevated pressures and cyclic testing to prove the

A joint is subjected to a specified internal negative pressure. This also simulates an external positive

Two methods are specified for the arrangement in 9.5, Method A and Method B. Method A is the default

When under pressure, the joint is monitored for leakage. After each test condition (see Table 1) the joint

In addition, a test at elevated positive static pressure is conducted to prove the structural design of the

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

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

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.

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

b) a strap or cradle (100 ± 5) mm wide (item 7 in Figure 2), supporting at least a 120° arc of the

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

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

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.

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.

The source of hydrostatic pressure shall be capable of applying the required pressures including, as

Pressure gauges shall be capable of measuring the positive and negative pressures. The gauges shall be

The vacuum pump shall be capable of producing the required negative gauge pressure (see 9.2).

The means of applying the required deformation forces F (see 9.3 and 9.4) and bending forces F (see

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

The test piece shall comprise an assembly of two pieces of pipe of the size and pressure class, as