ISO 13956:2025

Plastics pipes and fittings - Decohesion test of polyethylene (PE) saddle fusion joints - Evaluation of ductility of fusion joint interface by tear test

This document specifies a method for the evaluation of the ductility of the fusion joint interface of assemblies of polyethylene (PE) pipe and electrofusion saddles, intended for the conveyance of fluids. NOTE The applicability of this method depends upon the design of the saddle. If not applicable, the strip-bend test according to ISO 21751[1 08D0C9EA79F9BACE118C8200AA004BA90B0200000008000000100000005200650066006500720065006E00630065005F007200650066005F0031000000 ] is considered an alternative.

Tubes et raccords en matières plastiques — Essai de décohésion des selles en polyéthylène (PE) assemblées par soudage — Évaluation de la ductilité de l'interface de soudage par essai d'arrachement

General Information

• Status: Published
• Publication Date: 06-Nov-2025
• ICS: 23.040.60 - Flanges, couplings and joints
• Technical Committee: ISO/TC 138/SC 5 - General properties of pipes, fittings and valves of plastic materials and their accessories -- Test methods and basic specifications
• Drafting Committee: ISO/TC 138/SC 5 - General properties of pipes, fittings and valves of plastic materials and their accessories -- Test methods and basic specifications
• Current Stage: 6060 - International Standard published
• Start Date: 07-Nov-2025
• Due Date: 03-Feb-2026
• Completion Date: 07-Nov-2025

Relations

• Revises: ISO 13956:2010 - Plastics pipes and fittings - Decohesion test of polyethylene (PE) saddle fusion joints - Evaluation of ductility of fusion joint interface by tear test
• Effective Date: 06-Jun-2022

Overview

ISO 13956:2025 - "Plastics pipes and fittings - Decohesion test of polyethylene (PE) saddle fusion joints - Evaluation of ductility of fusion joint interface by tear test" is the 2025 second edition test method for assessing the ductility of fusion joint interfaces between PE pipes and electrofusion saddles. The standard specifies how to perform a tear (decohesion) test to characterise brittle versus ductile failure at the fusion plane and to quantify the percentage of brittle fracture.

Key topics and technical requirements

• Scope & applicability: Applies to assemblies of PE pipe and electrofusion saddles intended for fluid conveyance. Applicability depends on saddle design; if unsuitable, the strip-bend test in ISO 21751 is given as an alternative.
• Test principle: Apply a load to separate the saddle from the pipe and evaluate the fracture appearance and brittle fracture percentage.
• Apparatus: Defined test setups include tensile equipment Type A1/A2, compression equipment Type B, and for large diameters Type C (with fixtures). Loading pin dimensions and clamping arrangements are specified.
• Conditioning & timing: Testing is carried out at least 24 h after jointing; condition specimens at (23 ± 2) °C for at least 6 h before testing. Test temperature (23 ± 2) °C.
• Test speeds: Nominal test speed (100 ± 10) mm/min; if separation cannot be achieved, a lower speed of (25 ± 5) mm/min may be used.
• Measurements & calculations:
  • Measure maximum brittle fracture radial length l and overall fusion zone length L. Compute percentage brittle fracture Ld = (l / L) × 100.
  • Measure brittle area A and theoretical fusion zone area Anom; compute percentage brittle area Ad = (A / Anom) × 100.
  • Non-fused air pockets in the fusion plane are treated as brittle fractures.
• Reporting: Test report must reference ISO 13956:2025 and include component IDs, dimensions, fusion conditions, test mode, failure type, L and A percentages, photos if L ≥ 25% or A ≥ 12%, and other relevant details.
• Recommendation: If product standards do not specify limits, Annex A recommends L ≤ 50% and A ≤ 25% as acceptance guidance.

Applications and users

ISO 13956:2025 is intended for:

• Manufacturers of PE pipes and electrofusion fittings for quality control and product development.
• Independent testing laboratories performing mechanical qualification and failure-mode analysis.
• Specifiers and standards committees writing product or installation standards.
• Contractors and utilities seeking verification of joint ductility for safety and long-term performance.

Practical uses include verifying fusion procedures, diagnosing joint defects (e.g., air pockets), and supporting certification or acceptance testing for pipeline components.

Related standards

• ISO 21751 - Strip-bend decohesion test for electrofusion assemblies (alternative when ISO 13956 method is not applicable).
• ISO 11413 - Preparation of test piece assemblies between PE pipe and electrofusion fittings (guidance referenced for specimen preparation).

Keywords: ISO 13956:2025, decohesion test, polyethylene saddle fusion joints, electrofusion saddle, tear test, fusion joint ductility, PE pipes, brittle fracture percentage, tensile/compressive test method.

Standards Content (Sample)

International
Standard
ISO 13956
Second edition
Plastics pipes and fittings —
2025-11
Decohesion test of polyethylene
(PE) saddle fusion joints —
Evaluation of ductility of fusion
joint interface by tear test
Tubes et raccords en matières plastiques — Essai de décohésion
des selles en polyéthylène (PE) assemblées par soudage —
Évaluation de la ductilité de l'interface de soudage par essai
d'arrachement
Reference number
© ISO 2025
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
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Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Apparatus . 1
5.1 General .1
5.2 Tensile test equipment — Type A1 or A2 .1
5.3 Compressive test equipment — Type B .3
5.4 Test equipment — Type C .3
6 Sampling . 4
6.1 Preparation of test pieces .4
6.2 Number of test pieces .5
7 Conditioning . 5
8 Procedure . 5
9 Test report . 7
Annex A (informative) Recommendation . 9
Bibliography .10

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 13956:2010), which has been technically
revised.
The main changes are as follows:
— a Note has been added to the scope;
— guidance on assessment of air pockets in the fusion zone has been given in Clause 8, Figure 5 and Figure 6;
— symbols have been aligned with relevant ISO documents;
— Figure 5 has been corrected.
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
International Standard ISO 13956:2025(en)
Plastics pipes and fittings — Decohesion test of polyethylene
(PE) saddle fusion joints — Evaluation of ductility of fusion
joint interface by tear test
1 Scope
This document specifies a method for the evaluation of the ductility of the fusion joint interface of assemblies
of polyethylene (PE) pipe and electrofusion saddles, intended for the conveyance of fluids.
NOTE The applicability of this method depends upon the design of the saddle. If not applicable, the strip-bend test
[1]
according to ISO 21751 is considered an alternative.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
4 Principle
A load is applied to the saddle of an assembly of an electrofusion saddle fused onto pipe.
The ductility of the fusion joint interface is characterised by the appearance of t
...