Damage to coated plastics pipes from trenchless laying techniques

Report, 2006

This project aims at evaluating an external coating on plastics pipes; and its protective function against scratches and scoring damage from trenchless laying techniques. PE100 pressure pipes with four different coatings were tested in horizontal drilling and pipe bursting field trials. During the tests, the lengthwise and cross-sectional deformations of the pipe were measured along with the traction force. The pipes’ surfaces were examined with respect to scratches, and the depth of the most prominent ones were determined. Of the two laying techniques, pipe bursting was the one that caused the deepest scratches. Horizontal drilling was not significantly worse than ordinary handling during transport and preparation with respect to scratch depth. Dragging of the pipe above ground on asphalt surfaces caused severe damage to the pipe wall. The deepest scratches were seen on two pipe selections with soft coatings. Due to their thickness, however, these coatings were not penetrated and thus successfully protected the main pipe wall. The hardest coating tested, made of polypropylene, was also the thinnest one, and it was penetrated at one location during the pipe bursting test. The traction force on the pipe was significantly higher during horizontal drilling than during pipe bursting. On the other hand, ovalisation of the pipe’s cross-section was greater during pipe bursting.