There are a large number of different mechanical test methods available to assess the quality of butt fusion and electrofusion (EF) welded joints in polyethylene (PE) pipes. These include various short-term tests on specimens cut from the weld, such as bend tests, tensile tests and peel tests, as well as long-term specimen tests and hydrostatic pressure tests. TWI has also developed a whole pipe tensile creep rupture test specifically to determine the long-term performance of welded joints in PE pipes. Unfortunately, little published information exists on the correlations that may or may not exist between the results from these different test methods. This paper describes two studies carried out at TWI to compare the results from various short-term and long-term, specimen and whole pipe, mechanical test methods on both butt fusion and EF joints with different nominal weld qualities. Also described are two European projects that have been carried out to develop ultrasonic non-destructive test (NDT) methods for inspecting butt fusion and EF joints in PE pipes.
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