Non-linear Analysis of the Expanding Stage in the UOE Pipe Manufacturing Process

In recent years, the increasing demand for energy has pushed oil and gas activities into more remote regions of the sea, which resulted in laying pipelines at depths greater than 2000m where they are vulnerable to collapse failure. Therefore, pipes are required to be manufactured with higher circularity and thicker wall thickness, this introduces a challenge for UOE pipe manufacturers as the process will involve the application of high forces in each forming step to
form the plate into a pipe, and this could affect the integrity of equipment and tools such as the mechanical expander die segments. The aim of this paper is to investigate the expansion stage in the UOE pipe manufacturing process using Finite Element Analysis (FEA). Firstly, the stresses encountered by the pipe and mechanical expander dies during the expansion stage were analysed. The study revealed that the expansion stage causes the formation of wave patterns and
concavities on the pipe surfaces which results in wall thickness variation. In addition, the study showed that the pipe ovality after the expansion is between (0.034%) and (0.055%). Furthermore, the study revealed that the Von-Mises stresses, the mechanical expander dies experience during the expansion are about (10.26%) lower than the pipe’s yield strength. Secondly, the FEA was carried out to investigate the benefit of optimising the mechanical expander dies design on the finished pipe shape. This study showed that reducing the expander
die radius by (1%) significantly improves the pipe shape compared to the original expander die size and lowers the stress concentration on the expander dies.