ISO 8533:2019

INTERNATIONAL ISO
STANDARD 8533
Second edition
2019-08
Glass-reinforced thermosetting
plastics (GRP) pipes and fittings —
Test methods to prove the design of
cemented or wrapped joints
Tubes et raccords en plastiques thermodurcissables renforcés de
verre (PRV) — Méthodes d'essai pour confirmer la conception des
assemblages scellés ou enrobés
Reference number
©
ISO 2019
© ISO 2019
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ii © ISO 2019 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
5 Apparatus . 2
5.1 End sealing devices . 2
5.1.1 General. 2
5.1.2 Capable of applying the end loads . 3
5.1.3 Not capable of applying the end loads . 3
5.2 Supports . 3
5.2.1 End thrust supports . 3
5.2.2 Straps or cradles. 3
5.2.3 Special supports . 3
5.3 Source of hydrostatic pressure . 3
5.4 Means of measuring the gauge pressure . 3
5.5 Vacuum pump . 3
5.6 Means for applying the required bending force . 3
6 Test pieces . 3
6.1 Test arrangement for tests detailed in 9.2, 9.4 and 9.5 . 3
6.2 Test arrangement for tests detailed in 9.3 . 4
6.3 Number of test pieces . 6
7 Conditioning . 6
8 Test temperature . 6
9 Procedure. 6
9.1 General . 6
9.2 Negative pressure . 7
9.3 Resistance to bending with pressure and end thrust . 8
9.3.1 Method A . 8
9.3.2 Method B . 8
9.4 Resistance to internal cyclic pressure . 9
9.5 Resistance to maintained internal pressure .10
9.6 Resistance to bolt-tightening torque .10
10 Test report .10
Annex A (normative) Calculation of the additional force F and limiting deflection Δ used in
A
9.3, Method A .12
Annex B (normative) Calculation of the bending load F used in 9.3, Method B .13
B
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
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ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
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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).
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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 second edition cancels and replaces the first edition ISO 8533:2003, which has been technically
revised. It also incorporates the Amendment ISO 8533:2003/Amd1: 2012. The main changes compared
to the previous edition are as follows:
— changed the Scope to mention that the test procedure is a destructive test and that the bending test
is limited up to DN 600;
— changed the Scope to cover the proof of structural design of cemented or wrapped joints;
— the Terms and definitions clause was added to this document;
— changed testing sequences from mandatory to recommended;
— modified test sequence for the proof of the design, Clause 9;
— changes in Table 1 with modified testing sequences for the proof of the design of cemented or
wrapped joints;
— modification of bending test sequence;
— addition of an alternative bending test (Method B).
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.
iv © ISO 2019 – All rights reserved

Introduction
In a pipework system, pipes and fittings of different nominal pressures and nominal stiffness 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 of the pipeline, but not necessarily of 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.
The material-dependent parameters and/or performance requirements are stated in the referring
standard.
INTERNATIONAL STANDARD ISO 8533:2019(E)
Glass-reinforced thermosetting plastics (GRP) pipes and
fittings — Test methods to prove the design of cemented or
wrapped joints
1 Scope
This document specifies methods of test for cemented or wrapped joints for buried and above ground
glass-reinforced thermosetting plastics (GRP) piping systems. This document is only applicable to the
joint and covers methods of test to prove its design. It assumes that the joint either is or is not intended
to be subject to the effects of hydrostatic end thrust.
The tests detailed in 9.2, 9.4 to 9.6 inclusive are applicable to cemented or wrapped joints intended to
be used in buried or above-ground applications. The bending tests detailed in 9.3 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 may be considered appropriate.
With the exception of procedure detailed in 9.3, these test procedures are applicable to joints for pipes
and fittings of all nominal sizes. The tests detailed in 9.3 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 applied for type testing purposes only.
This document is applicable only to the joint and specifies methods of test 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.
3.2
bending
beam bending in the pipe and joint configuration as a result of a vertical force on the cemented or
wrapped joint
4 Principle
A test piece comprising two pieces of pipe jointed together with a cemented or wrapped joint is
subjected to a specified internal pressure. The procedure includes prolonged static tests at elevated
pressures and cyclic testing to prove the structural design of the cemented or wrapped joint.
A cemented or wrapped joint is subjected to a specified internal negative pressure. This also simulates
an external positive pressure.
All tests except the bending tests in 9.3 shall be carried out with or without end thrust. The bending
test in 9.3 is only applicable for joints intended to resist end thrust.
Two methods are specified for the arrangement in 9.3, Method A and Method B. Method A is the default
method. Method B may be agreed between the purchaser and manufacturer.
When under pressure, the joint is monitored for leakage. After each test condition (see Table 1) the joint
is inspected for signs of damage.
NOTE 1 The only reason for testing the resistance to external pressure differential is to ensure adequate
safety against infiltration of pollutants through the joint into the fluid carried in the piping system. Under these
test conditions pipes with low stiffness may require support to prevent buckling.
NOTE 2 It is assumed that the following test parameters are set by the standard making reference to this
document:
— whether GRP to GRP or GRP to metal flange tests are to be performed;
— 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 bending force F or F ;
A B
— the permissible change in negative pressure.
In all 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.
5 Apparatus
5.1 End sealing devices
5.1.1 General
The end-sealing devices shall be of sizes and type appropriate to the components under test.
2 © ISO 2019 – All rights reserved

5.1.2 Capable of applying the end loads
If the joint is to be tested with an end load, then the end-sealing devices shall be anchored to the pipes
to transmit the end thrust loads.
5.1.3 Not capable of applying the end loads
If the joint is to be tested without the end load, then the end-sealing devices shall not be anchored to
the pipes.
5.2 Supports
5.2.1 End thrust supports
End thrust supports, if required, comprising part of the rig, which shall be capable of supporting the
end thrust induced by the internal pressure, but which shall not otherwise support the joint.
5.2.2 Straps or cradles
Straps or cradles for use as supports shall be of sufficient width for the pipe and joint components of the
test piece (see Figure 1).
The straps or cradles shall not have a detrimental effect on the test piece, e.g. by applying point loads.
5.2.3 Special supports
Special supports shall be used if necessary to prevent buckling of the pipe barrel during external
pressure differential testing (see 9.2).
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 Means of measuring the gauge pressure
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. The pressure shall be measured at the
top of the pipe.
5.5 Vacuum pump
The vacuum pump shall be capable of producing the required negative gauge pressure (see 9.2).
5.6 Means for applying the required bending force
The means of applying the required bending force F or F shall be calibrated to an accuracy of ±5 % of
A B
the value to be measured, (see 9.3, Annexes A and B).
6 Test pieces
6.1 Test arrangement for tests detailed in 9.2, 9.4 and 9.5
The test piece shall comprise an assembly of two pieces of pipe of the correct size and pressure class,
as specified in the referring standard and the joint to be tested. The total effective length, L, of the
assembly shall be not less than that specified in the referring specification and shall allow, if requir
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