ISO 9853:2026

International
Standard
ISO 9853
Second edition
Thermoplastics piping systems —
2026-09
Crushing test for moulded fittings
Systèmes de canalisations en matières thermoplastiques — Essai
à l'écrasement pour les raccords moulés
Reference number
© ISO 2026
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ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
5 Apparatus . 2
6 Test pieces . 2
7 Conditioning . 2
8 Procedure . 3
9 Test report . 4
Annex A (informative) Recommended percentage deformation for fittings . 5
Bibliography . 6

iii
Foreword
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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 5, General properties of pipes, fittings and valves of plastic materials and
their accessories — Test methods and basic specifications.
This second edition cancels and replaces the first edition (ISO 9853:1991), which has been technically
revised.
The main changes are as follows:
— the title has been revised;
— in the Scope, the following materials have been added: PVC- HI, PVC-C, PE, PP, ABS, PVDF, PPSU and PA-U;
— Clause 2 on normative references have been added;
— the test parameters have been modified due to the addition of different materials;
— the requirements of test apparatus have been detailed.
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
Introduction
Moulded fittings for thermoplastics piping systems can be crushed without their failing if they contain no
residual stresses as a result of the moulding process. However, if these residual stresses are excessively
high, the fitting will fail when a crushing force is applied.
The percentage deformation of a fitting, in relation to its initial diameter, constitutes a simple criterion for
the selection of fittings having an acceptable level of internal stress.
Meanwhile, when fittings are the initial moulds from injection moulding process, some potential defects
might also exist in these fittings. A crushing test can provide an effective acceptable level of internal stress
for fittings.
v
International Standard ISO 9853:2026(en)
Thermoplastics piping systems — Crushing test for moulded
fittings
1 Scope
This document specifies a test method to determine if a fitting will fail in crushing mode under compression
before a predefined percentage deformation of moulded fittings for thermoplastics piping systems and
provides recommended percentage deformation for fittings (see Annex A).
This document applies to fittings made from unplasticized poly(vinyl chloride) (PVC-U), high-impact
poly(vinyl chloride) (PVC-HI), chlorinated poly(vinyl chloride) (PVC-C), polyethylene (PE), polypropylene
(PP), acrylonitrile-butadiene-styrene (ABS), poly(vinylidene difluoride) (PVDF), poly(phenyl sulfone)
(PPSU) and unplasticized polyamide (PA-U).
This document can also be applied to moulded fittings made from other thermoplastics, in which case the
test conditions can differ.
2 Normative refe
...