Fracture & Resistance # 1992 Eindhoven
GAZ DE FRANCE has devised a method for monitoring the length-wise development of a longitudinal crack via the wall of a pipe submitted to constant deformation. Deformation is induced by inserting a cone of graded diameter into a pipe end.
This test permits an easy, rapid (test duration is roughly five days) and inexpensive classification of materials according to their crack resistance.
Slow crack growth (SCG) is one of the possible causes of if, colyethylene (PE) pipe degradation. The phenomenon is based on the propagation of a crack, generally from the outer surface to the inner surface of the pipe. This crack is generated by the existence of a preliminary defect on the pipe which may be due for instance to scratches caused during pipe laying or to accidental notches. The propagation of the crack accross the pipe wall may take several years before leading to a gas leak.