Optimization of UOE Pipe Manufacturing Process for Improved Collapse Performance Under External Pressure

Abstract

Large-diameter pipes used in offshore applications are commonly manufactured by cold-forming plates through the UOE process. Collapse experiments have demonstrated that these steps, especially the final expansion, degrade the mechanical properties of the pipe and result in a reduction in its collapse pressure, upwards of 30%. In this study, the UOE forming process has been modeled numerically so that the effects of press parameters of each forming step on the final geometry and mechanical properties of the pipe can be established. The final step involves simulation of pipe collapse under external pressure. An extensive parametric study of the problem has been conducted, through which ways of optimizing the process for improved collapse performance have been established. For example, it was found that optimum collapse pressure requires a tradeoff between pipe shape (ovality) and material degradation. Generally, increase in the O-strain and decrease in the expansion strain improve the collapse pressure. Substituting the expansion by compression can not only alleviate the UOE collapse pressure degradation but can result in a significant increase in collapse performance.

The JCOE/JCOC manufacturing process and collapse resistance of submarine pipeline

“…3 The expanding process increases the circumferential yield stress of the pipeline, while the yield stress decreases during compression due to the influence of the Bauschinger effect. 51 Kyriakids et al 52,53 developed a prediction tool to predict the collapse pressure of the pipeline. The model shows that the initial ovality will greatly affect the collapse capacity, while the change of wall thickness has little effect on the collapse capacity, and the residual stress has little effect on the pipe with lower D / t .…”