Pipes, especially risers, pipelines, and umbilicals, are extensively used in the subsea production system. Umbilical, as a controlling component of subsea production system, as well as other pipes, will resist reeling, unreeling, and additional processing before on-site installation, which might lead to yielding and plastic deformation of the pipe. This plastic deformation often results in low cycle fatigue (LCF) issue of the pipes, and how to effectively estimate the corresponding fatigue life has become a topic of practical engineering interest. In the present paper, a structural strain method is applied to determine the elastic core of the pipe and to calculate the pseudo structural stress. The pseudo structural stress concept has been applied to analyze the pipe in LCF regime. Further, the results obtained have been compared with the experimental and other available data. It can be seen that the results coincide well with the experimental data. In addition to the demonstrated effectiveness, the key advantage of this pseudo structural stress approach is the simplicity in dealing with girth-welded pipe sections, since finite element stress analysis is unnecessary.

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