scope:

This document describes the time of flight diffraction (TOFD) testing of polyethylene butt fusion (BF) joints, including pipe-to-pipe, pipe-to-fitting and fitting-to-fitting joints, used for the conveyance of fluids. This document provides a test, whereby the presence of imperfections such as voids, inclusions, lack of fusions, misalignment and particulate contamination in the BF joints can be detected. The document is only applicable to polyethylene pipes and fittings without a barrier to ultrasonic waves.

This document also provides requirement for procedure qualification and guidance for personnel qualifications which are essential for the application of this test method.

This document also covers the equipment, the preparation and performance of the test, the indication assessment and the reporting for polyethylene BF joints. The acceptance criteria are not covered in this document.

NOTE 1 At the present time laboratory experiences exist on the use of TOFD for polyethylene butt fusion joints and/or reference blocks of wall thickness between 8 mm to 100 mm^{[1][2][3][4][5][6]}. Recently field experience on butt fusion joints in HDPE pipes has been reported^[7].

NOTE 2 Round robin testing has shown that TOFD is a viable method for enhancing the integrity assessment of butt-fusion joints^[14].

NOTE 3 TOFD techniques for cold fusion detection are known to be available. However further research, verification and experience are needed to transfer the technique into an ISO Standard. This document does not provide any information regarding the detection of cold fusions^[14].