National foreword

This British Standard is the UK implementation of ISO 9853:2026.

The UK participation in its preparation was entrusted to Technical Committee PRI/88, Plastics piping systems.

A list of organizations represented on this committee can be obtained on request to its committee manager.

Contractual and legal considerations

This publication has been prepared in good faith, however no representation, warranty, assurance or undertaking (express or implied) is or will be made, and no responsibility or liability is or will be accepted by BSI in relation to the adequacy, accuracy, completeness or reasonableness of this publication. All and any such responsibility and liability is expressly disclaimed to the full extent permitted by the law.

This publication is provided as is, and is to be used at the recipient’s own risk.

The recipient is advised to consider seeking professional guidance with respect to its use of this publication.

This publication is not intended to constitute a contract. Users are responsible for its correct application.

Compliance with a British Standard cannot confer immunity from legal obligations.

This British Standard was published under the authority of the Standards Policy and Strategy Committee on 30 September 2026.

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).

ISO draws attention to the possibility that the implementation of this document may involve the use of (a) patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a) patent(s) which may be required to implement this document. However, implementers are cautioned that this may not represent the latest information, which may be obtained from the patent database available at www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.

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 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.

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.

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 references

3 Terms and definitions

4 Principle

5 Apparatus

5.1

5.2

5.3

5.4

5.5

6 Test pieces

7 Conditioning

8 Procedure

8.1

8.2

8.3

8.4

8.5

8.6

8.7

9 Test report

Bibliography