What procedures are used for testing the assembly?

Different methods of testing finished fusion joints in PE pipes have been developed in different countries. They vary in their approach to the question of how a joint should be tested and to date a standard system across Europe has not been agreed upon.

Whilst ultrasonic non-destructive testing (NDT) of welded joints is widely used on steel pipelines, the development required to use the technique on plastic pipes has taken much longer. There are however now several organisations that offer a service of inspecting both butt and electrofusion joints. Georg Fischer in Switzerland and TWI (The Welding Institute) in the UK are two of the most active organisations in this field.

Some of the existing testing standards are referenced below. Note that EN 12007-2 and ISO/TS 10839 detail how to undertake on-site external weld bead removal and manual testing.

References

EN 13100-1:2017 Non-destructive testing of welded joints of thermoplastics semi-finished products - Visual examination

ISO/TS 10839:2022 Polyethylene pipes and fittings for the supply of gaseous fuels - Code of practice for design, handling and installation (Section 8.3 - Visual inspection during laying)

EN 12007-2:2012 Gas infrastructure. Pipelines for maximum operating pressure up to and including 16 bar - Specific functional requirements for polyethylene (MOP up to and including 10 bar) (Annex B  - Fusion joint integrity - visual inspection)

ISO 21751:2011 Plastics pipes and fittings - Decohesion test of electrofusion assemblies - Strip-bend test (Destructive testing of electrofusion joints)

EN 12814-4:2018 Testing of welded joints of thermoplastics semi-finished products - Part 4: Peel test (Destructive testing of electrofusion joints)

ISO 13953:2001/Amd 1:2020 Polyethylene (PE) pipes and fittings - Determination of the tensile strength and failure mode of test pieces from a butt-fused joint

ISO 13954:1997 Plastics pipes and fittings - Peel decohesion test for polyethylene (PE) electrofusion assemblies of nominal outside diameter greater than or equal to 90 mm

ISO 13955:1997/Amd 1:2020 Plastics pipes and fittings - Crushing decohesion test for polyethylene (PE) electrofusion assemblies

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

ISO 13957:1997 Plastics pipes and fittings - Polyethylene (PE) tapping tees - Test method for impact resistance