Circumferentially oriented inserts for butt-welded pipe joints - to inhibit propagation of longitudinal cracks (PT 19.6.80)

摘要

A hoop of circumferentially oriented material is used as an insert between the faces of a butt-welded joint in a thermoplastic pipe. The degree of circumferential molecular orientation in the insert is 10-100% and is greater than the degree of longitudinal molecular orientation in the pipe walls. For fusion welded joints in pipes for pressurised systems, e.g. distributing gas or water. The inserts are provided to deviate any cracks propagating longitudinally through an adjacent section of pipe, to divert the crack into a radial plane and prevent crack propagation to the next segment of pipe.