Prediction of Transient Pressures in Polyethylene Pipes

Abstract

Increasingly sophisticated numerical modelling techniques for the simulation of pipeline pressure transients have been developed over the past decades since the relatively widespread availability of digital computers. Introduction of new pipe materials, in particular plastics, has also taken place. These materials have mechanical characteristics that differ from those of more traditional pipe materials. To make the best use of numerical methods requires that mechanical behaviour and properties of plastics are well understood and documented. This paper describes how polyethylene pipes may differ in their response to pressure surge from that of other pipe materials. Numerical model developments are described which are aimed at producing a more accurate simulation of surge behaviour. In particular two ways in which polyethylene pipe behaviour departs from that of some other pipe materials are examined. One of these relates to the time-dependent modulus of the material and the other to the deformable nature of the cross-section which can result from its relatively high flexibility. Potential benefits of using polyethylene pipes are considered from a pressure surge viewpoint.