Date of Award

3-2-2021

Publication Type

Master Thesis

Degree Name

M.A.Sc.

Department

Civil and Environmental Engineering

Keywords

Cyclic, Energy, Fatigue, Oil and Gas, Pipes, Wrinkle

Supervisor

Sreekanta Das

Rights

info:eu-repo/semantics/embargoedAccess

Abstract

The energy industry has since been faced with the issue of development of wrinkle defect on buried pipelines located in vicious environment. Although, there have been different literatures on how to assess the integrity of pipelines with structural defects such as; corrosion, dents, buckles and welds, limited research data or guideline(s) are available on how to assess the severity of small wrinkle defects. Failure to assess the severity of these wrinkle defects, especially in buried pipelines located in the regions prone to geotechnical movement and extreme seasonal temperature variation, may lead to shutdown of the pipeline operations, and as result lead to loss of revenue. Therefore, this current study is focused on investigating the failure and behaviour of wrinkled pipes with varying wrinkle geometry, when they are subjected to axial cyclic loads representative of extreme seasonal temperature variation and cyclic freeze-thaw. This research program was conducted using both experimental method and finite element analysis (FEA) based approach. This study shows that a pipe with a wrinkle defect subjected to displacement-controlled axial cyclic loading, may fail by fatigue and result to fracture at the crest of the wrinkle due to localized stress and strain concentration. Additionally, the fatigue life of a wrinkled pipe is dependent on the magnitude of internal pressure applied and the type of cyclic loading applied. A methodology based on the strain life approach used in this study, was considered sufficient in analysing the remaining life of wrinkled pipes subjected to displacement-controlled axial cyclic loading.

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