TWI Industrial Member Report Summary 913/2008
By M Troughton and C Brown
Welded polyethylene (PE) pipe systems have been in use for around 50 years for the pressurised distribution of fluids such as potable water, sewage and domestic gas. The long-term performance of the pipes themselves is well understood from established regression analysis techniques on pressurised samples at elevated temperatures. However, the longevity of a welded pipe system also depends on the long-term performance of the joints. Numerous short-term tests are used to quantify the quality of electrofusion (EF) joints but there has been little work to correlate the results from these tests with those from long-term tests and, therefore, they cannot yet be used to give an indication of the long-term performance of the joints.
The work described in this report, which is part of the Polytec Systems European-funded project to develop and validate non-destructive testing techniques for EF joints in PE pipes, was carried out to compare the results of various short- and long-term tests currently carried out in industry on EF joints in PE pipes containing various different flaws.
- Correlate the results from short- and long-term coupon and whole pipe tests on EF welds in PE pipes made under different welding conditions or containing different known flaws.
- Identify the most suitable mechanical test methods for predicting the long-term performance of EF welds.