Probabilistic transgranular stress corrosion cracking analysis for oil and gas pipelines

The crack morphology of transgranular stress corrosion cracking (TGSCC) suggests that the mechanism of growth and the condition at which TGSCC occur is different than that of intergranular stress corrosion cracking (IGSCC). Several attempts have been made to characterize IGSCC probabilistically; however, limited effort has been noticed for TGSCC. This paper attempts to analyze TGSCC probabilistically. The study includes assessment of probability of failure for low pH, TGSCC by R6 approach/BS 7910 approach/API 579 approach, which considers plastic yielding and linear elastic fracture mechanics, CSA Z 662-07 burst model approach and author's proposed strain-based approach. The paper observes that failure assessment diagram (FAD) based approaches (R6, BS 7910, and API 579) calculate least failure probability compared to CSA Z 662-07 burst model approach. The authors also noticed that their proposed hoop strain-based approach calculates closely to CSA Z 662-07 burst model approach. Finally, the authors justified the rationality of the results obtained by their approach. © 2012 American Society of Mechanical Engineers.