Mark Heathcote, August, 2008

There has been a great deal of discussion throughout the industry about weld parameters recently and some of the information relating to this topic needs clarification.

Firstly, all the PIPA guidelines are reviewed regularly. PIPA has a working group, chaired by Bob Langdon (Dixon Industries), reviewing the industry guidelines for PE butt welding, POP003. As part of that review, the subject of high pressure weld procedures is being considered for inclusion.

Secondly, it needs to be understood that there are many weld parameters being used around the world to butt weld PE pipes. The current PIPA Guideline is based on a single low pressure process. The ISO draft includes the single low pressure approach, the British dual pressure approach and the American high pressure approach. There are other approaches, including those referred to as “fast fusion” processes, that sit outside of both the PIPA Guideline and the ISO Draft Standard.

Revision of the PIPA Guideline is timely as the revised ISO Draft Standard covering weld parameters has now reached the FDIS stage. This means the ISO Draft has basically been finalised with respect to the technical content and that any changes from this point, to the document will only be editorial in nature. Australia has an active involvement in the ISO working group, with Mike Stahmer (Vinidex) as our representative. The Chair of the ISO Working Group for this document is Ted Striplin (from McElroy), who, while in Australia, attended PIPA’s open information session with interested PIPA members on 6 August in Sydney, to discuss the high pressure welding.

Significant interest has been generated by an article appearing in the Trenchless Australasia Magazine, written by Ted Striplin, discussing low and high pressure welding. An aspect of the article that has created much discussion, was the estimates of achievable weld productivity using the two approaches. What was not clear in that article, but was subsequently clarified by Ted, was that the number of welds that have been estimated as achievable in a “typical working day” are not based on parameters that follow the ISO draft standard for either high or low pressure techniques. The cooling times used to make these estimates are shorter than those specified in the ISO Draft. Ted’s article has, however, achieved his objective of stimulating debate on the benefits of various fusion methods, and his ultimate aim of improving the cost competitiveness of PE pipe systems.

The PIPA Working Group headed by Bob Langdon will complete their review shortly and a revised POP003 will follow. Until that change happens, PIPA continues to maintain the current position endorsing the long standing parameters in POP003.

For Further information please contact :
Plastics Industry Pipe Association of Australia Ltd
Suite 246, 813 Pacific Hwy, Chatswood NSW 2067
or email plasticspipe@pipa.com.au

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