A study of pipeline response during reel-lay installation

Dawood, Ali Ahmed (2014) A study of pipeline response during reel-lay installation. Masters thesis, Memorial University of Newfoundland.

[English] PDF - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. Download (2MB)

Abstract

Pipeline installation by reel-lay is among the most cost effective methods currently being utilized in the offshore industry. It is advantageous over other conventional methods both in terms of cost and the rate at which the pipeline can be laid on the seabed. Reel-laying however, subjects a pipe to large bending which induce plastic strain reversals as the pipe is reeled on and off followed by aligning and straightening before exiting the installation vessel. Bending of a pipe beyond its elastic limit can change its initial mechanical properties. The realm of analyzing pipe response subjected to plastic bending holds a significant research potential for accurate assessment of the mechanical behavior of the pipeline. The current research effort aims at addressing some of the scenarios that may arise during reeling with the help of finite element methods (FEM). Pipe reeling was simulated using two different calibrated models for a perfect pipe. The study of material variation and weld offset were examined initially. The study was then extended to incorporate the pipe geometric imperfections and bifurcations, ovality, material combination, weld offset and joint to joint variations. The FEM were used to examine pipe behavior and led to conclusions regarding the stress and strain distributions that the pipeline experiences during the reeling process. Moreover, it was concluded that the girth-weld area hold critical importance during pipe bending during various stages of the reeling process. Incorporation of anisotropic properties i.e., the sensitivity of a material against the direction of applied load, in the material model was suggested to provide a more realistic response of the pipeline.

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