Mon, 08 December, 2025
TWI Industrial Members are invited to join a new Joint Industry Project (JIP) to investigate the ‘Production of Flawed Butt Fusion Joints in PE Pipes for the Evaluation and Qualification of Ultrasonic NDT Systems.’
Industrial interest in the use of ultrasonic non-destructive testing (NDT) of butt fusion (BF) joints in polyethylene (PE) pipes is gaining momentum due to the publication of the ISO Technical Specifications ISO/TS 22499 and ISO/TS 24399. There is also an increasing number of companies providing such a service.
However, the process for performing ultrasonic inspection on PE pipes is different to that for metallic pipe joints. The attenuation of the ultrasonic signal is greater for PE than with metals while the velocity of the ultrasound is slower and the types of flaws are different from those found in metal joints. Because of this, the systems used for the NDT inspection of metallic pipe welds will not work on PE pipes, creating a need for ultrasonic probes, wedges, manipulators and procedures to be designed specifically for non-metallic pipes.
To further complicate matters, it can be both costly and challenging for pipeline operators to assess the performance of a given NDT provider. The procedure to qualify NDT procedures in ISO/TS 22499 and ISO/TS 24399 involves making 21 BF joints for each of the four pipe wall thicknesses ranges. Of these, five joints should contain no flaws so they can be used by the NDT provider to set up their equipment and procedures. The remaining 16 joints are used for blind inspections, with eight containing no flaws, two containing embedded lack of fusion flaws, and six containing fine particulate contamination.
These joints are expensive to produce, making it costly for individual companies to produce a set of joints, especially should they need to cover the entire pipe wall thickness ranges from 8-100mm, which would require the manufacture of 84 joints.
Instead, it was proposed that a central library of flawed joints is created at TWI, using our experience in the insertion of consistent flaws into welding PE joints. The can then be borrowed as required by other companies. TWI is perfectly placed to provide this resource as we wrote the flaw insertion procedures given in the annexes of the ISO Technical Specifications.
TWI will discuss the required wall thickness ranges, pipe diameters and SDRs with project sponsors, before manufacturing the required number of BF joints as specified in the ISO technical specifications, using the procedures given in the annexes of the technical specifications documents.
The joints would be stored at our headquarters near Cambridge and made available to the project sponsors free of charge (aside from shipping costs) for ultrasonic NDT system assessments, after which they should be returned to TWI so other sponsors can use them. A report will also be produced detailing the manufacture of the welded joints, as well as associated trials and tests.
Interested parties can find out more and download the full project outline, here:
https://www.twi-global.com/what-we-do/research-and-technology/research-programmes/joint-industry-projects/production-of-flawed-butt-fusion-joints-in-pe-pipes-for-the-evaluation-and-qualification-of-ultrasonic-ndt-systems