Effects of Loading Sequences on Remaining Life of Plain Dents in Buried Liquid Pipelines
Publication: Journal of Pipeline Systems Engineering and Practice
Volume 10, Issue 2
Abstract
The integrity assessment of dents in liquid pipelines, as regulated by codes and standards, is based mostly on depth and threat integration, with strain analysis incorporated as a nonmandatory recommendation for gas pipelines. There have been incidents in which the current regulatory criteria have not successfully predicted imminent failures of dents, leading to operators using noncodified, more conservative approaches to maintain safety, typically resulting in poor dig efficiency. The dent assessment methods currently available in the industry do not account for the sequences of loading by which a dent may have formed. In this paper, the effects of different load sequences on the remaining life of plain dents in liquid pipelines are demonstrated using a validated finite-element analysis. A parametric study is carried out to confirm that the findings hold true for a range of pipe geometries, materials, and dent depths. The findings indicate that the severity and/or remaining life of a dent cannot be fully assessed based on its depth alone. The restraint condition, indenter shape, loading sequence, and pressure-cycling history should be considered for a reasonable assessment of the remaining life of plain dents.
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Any information or data pertaining to Enbridge Employee Services Canada Inc., or its affiliates, contained in this paper was provided to the authors with the express permission of Enbridge Employee Services Canada or its affiliates. However, this paper is the work and opinion of the authors and is not to be interpreted as Enbridge Employee Services Canada or its affiliates’ position or procedure regarding matters referred to in this paper. Enbridge Employee Services Canada and its affiliates and their respective employees, officers, director, and agents shall not be liable for any claims for loss, damage or costs, of any kind whatsoever, arising from the errors, inaccuracies, or incompleteness of the information and data contained in this paper or for any loss, damage, or costs that may arise from the use or interpretation of this paper.
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©2019 American Society of Civil Engineers.
History
Received: Aug 15, 2017
Accepted: Aug 21, 2018
Published online: Jan 3, 2019
Published in print: May 1, 2019
Discussion open until: Jun 3, 2019
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