Numerical model of UOE steel pipes: Forming processand structural behavior

Abstract

Deepwater pipelines are designed to withstand, without collapsing, the external pressureand bending imposed on them, either by the laying process or by the topology of the sea bottom. In previous publications CINI researchers have developed finite element models to predict collapse loadsand collapse propagation loads. Large diameter pipes for onshore and offshore applications are manufactured using the UOE process.The manufacturing process consists in the cold forming of heavy plates followed by welding and thenby an expansion. First the plate is pressed along its edges, formed into a U-shape and then pressedinto an O-shape between two semicircular dies. Afterwards the pipe is welded by SAW process andfinally is expanded. In this paper we develop a 2D finite element model to simulate the UOE process and the structuralbehavior of the formed pipes in external pressure collapse tests. Using the developed model we cananalyze the effects of the process parameters in each forming step on the final geometry and structuralproperties of the pipe