Squeeze-off of polyethylene pressure pipes: Experimental analysis

Abstract Squeeze-off is used in routine or emergency situations to stop, or nearly stop, flow in polyethylene (PE) pipe by flattening the pipe between parallel bars. Gas and water industries utilizing PE pipe in their systems have designed squeeze-off procedures to suit their pipe material, environmental conditions and constructional needs, where it may be inconvenient and/or expensive to isolate and empty pipelines. The method provides a quick shut-off the lines, saving many hours, and eliminates the need for dangerous, costly and lengthy excavations. Despite its widespread use, it is not known whether squeeze-off of the pipe damages the pipe and, if so, what is the degree of the damage and how it should be minimized. This paper is about the investigation of squeeze-off of pipes of various dimensions made from PE 80 and PE 100 grade high-density PE and crosslinked PE. Experimental investigation on the damage related with the squeeze-off of the pipes was carried out to study the influence of squeeze-off phenomenon on the short and long term performance of the pipes. Hydrostatic pressure tests were performed on the squeezed pipe to examine the degree of damage. The influence of squeezing ratio, pipe diameter and squeeze-off tool geometry on the overall pipe performance was also investigated.