Pipeline Defect Growth Prediction and Risk-based Integrity Management

• Author / Creator

  Xie, Mingjiang

• Pipelines have been used for several decades, and threats such as corrosion, fatigue crack and erosion increase the danger of leak or rupture. Faulty pipelines could lead to very expensive downtime and environmental damage. Therefore, it is essential to have effective ways to monitor, evaluate and assure the integrity of the pipeline, reduce the risk of leaks and rupture, and subsequently prevent hazards for the environment and population. In-line inspections (ILI) are performed periodically using smart pigging tools to detect pipeline defects such as corrosion and cracks. Significant advances are needed to accurately evaluate defects based on ILI data, predict defect growth and optimize integrity activities to prevent pipeline failures, and pipeline integrity management has drawn extensive and growing research interests.The aim of this thesis is to develop effective prognostics and risk-based management methods for performing inspection and maintenance activities for pipelines with crack or corrosion defects. This thesis starts with developing an efficient integrated methodology, and finally leads to more accurate predicted failure time distributions, better risk management, and consequently more effective pipeline integrity management system. This thesis provides a comprehensive review and fundamental knowledge on pipeline integrity management based on ILI data. Physics-based models and data-driven methods for predicting defect growth for pipelines with different categories of defects are discussed. Models and methods for risk-based integrity management are reviewed in this thesis.In the more advanced prognostics strategy, an integrated prognostics model for a pipeline with fatigue crack is proposed to make a better prediction. Rainflow counting method is employed in the proposed method for analyzing time-varying loading conditions of pipelines. We use aiiiCanadian pipeline operator’s field data to demonstrate the effectiveness of the proposed integrated approach. And the proposed method provides more accurate pipeline remaining useful life prediction compared to the traditional physics-based method.Studies are performed on improving risk-based maintenance strategies, which are currently widely adopted in pipeline industry. A simulation-based approach is developed for cost evaluation for pipelines with corrosion defects. The probability of failure (PoF) threshold is used as input random variable instead of fixed inspection interval. The uncertainties from multiple sources are considered here to make a better and more realistic prediction and that support decision making in industry. Examples are given to illustrate the proposed approach, and parametric studies are performed. The proposed method provides less cost rate results compared to the traditional fixed interval method.It is also important to determine the impact of ILI tool specifications on pipeline risks and costs, and thus recommend optimal integrity assessment and risk mitigation activities. By investigating the effect of ILI tool uncertainties on life-cycle costs and re-assessment results, suggestions for future improvement of ILI crack detection tools can be given. The effect of ILI tool uncertainties on re-assessment results for pipelines with crack defects is investigated. The long-term run scenario is also investigated considering crack initiation mechanism and probability of detection during each simulation run. Examples are used to illustrate the proposed approach, and sensitivity analysis is performed.The research in the thesis provides innovative methods for defect growth prediction and risk-based management in the pipeline industry. The developed approaches will contribute to preventing pipeline leak and rupture, unnecessary expensive downtime, and environmental threats.

• Subjects / Keywords

  • Prognostics
  • crack
  • Pipeline
  • Risk-based management

• Graduation date

  Spring 2019

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/r3-4jcv-nb37

• License

  Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.