Finite element analysis of the offshore reel-laying operations for double-walled pipe

Bending characteristics of double-walled pipe during offshore reel-lay operations have been investigated by finite element method. For the subsea pipeline reel-laying operations, the pipe is welded and spooled on the reel at docks. The pipe undergoes repetitive bending deformation while spooled on the reel. At the offshore destination, the pipeline installation is usually accomplished by spool-off, straightening, and laying out the pipelines. When the pipe is reeled out at sea, again it undergoes bending deformation. In order to simulate such a nonlinear behavior, the bending analysis of double-walled pipe consisting of SS400 and STS304 has been analyzed by finite element method and discussed for the respective cyclic bending processes using the relation of deformed compatibility of hysteresis loops. Furthermore, the feasibility analysis has also been made on the application of combined material properties which are based on the rule of mixture to the finite element analysis of double-walled pipe. The analysis results give a reasonable understanding of how materials behave during cyclic deformation of reel-laying operations. The application of combined material properties is proved to be feasible for the analysis of double-walled pipe with reasonable accuracy.