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 to detect imperfections such as voids, inclusions, lack of fusions, misalignment and particulate contamination in the BF joints. The document only applies to polyethylene pipes and fittings without a barrier to ultrasonic waves.

This document also provides requirements for procedure qualification and guidance for personnel qualifications, which are essential for applying this test technique.

This document covers the equipment, the preparation and performance of the test, the indication assessment and the reporting for polyethylene BF joints.

Acceptance criteria are not covered in this document.

NOTE 1        At present, 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]} Field experience on butt fusion joints in high density polyethylene (HDPE) pipes has been reported.^[7]

NOTE 2        Interlaboratory testing has shown that TOFD is a viable method for enhancing the integrity assessment of butt fusion joints.^[13]