Quantification of Uncertainties in Crack Growth Model and Operating Pressure for the Integrity Management of Pipelines Subjected to Stress Corrosion Cracking

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Stress corrosion cracking (SCC) is one of the leading causes of failure for oil and gas pipelines in Canada. According to the Canadian Energy Pipeline Association, 17% of the total pipeline incidents in Canada were due to SCC in 2017. SCC defects grow over time due to corrosion fatigue enhanced by hydrogen embrittlement, and, if unmitigated, can lead to pipeline ruptures with serious consequences in terms of human safety and environmental damage. There are significant uncertainties in the growth of SCC defects due to uncertainties in the pipe operating pressure, soil environments and inherent randomness of SCC. The proposed research project is a collaboration between Dr. Wenxing Zhou at the University of Western Ontario and scientists at CanmetMATERIALS research centre of Natural Resources Canada. The long-term objective of the collaboration is aimed at developing methodologies, models, and decision-support tools for risk-based integrity management of pipelines subjected to SCC. The proposed research project is the first step of this multi-year collaboration with the objective of quantifying the uncertainties in the growth models for SCC defects and internal operating pressures of oil and gas pipelines. SCC growth test data obtained from full-scale pipe specimens under realistic operating pressure and soil environments will be used to characterize the model uncertainties of SCC growth models. Operating pressure time-history records for oil and gas pipelines provided by pipeline operators in Canada will be employed to characterize the uncertainties in the pipe internal pressure. The proposed project will train two MESc students for a duration of one year. The research findings will provide the key knowledge for the implementation of SCC growth models in a risk-based pipeline integrity management framework.