Probabilistic Integrity Assessment of Corroded Gas Pipelines

Pressurized gas pipelines are subject to harmful effects from both the surrounding environments and the materials passing through them. Reliable assessment procedures, including fracture mechanics analyses, are required to maintain their integrity. Currently, integrity assessments are performed using conventional deterministic approaches, even though there are many uncertainties to hinder rational evaluations. Therefore, in this study, a probabilistic approach was considered for gas pipeline evaluations. The objectives are to estimate the failure probability of corroded pipelines in the gas and oil industries and to propose operating limit conditions for different types of loadings. To achieve these objectives, a probabilistic assessment program was developed using reliability index method and simulation techniques, and applied to estimate the failure probabilities of corroded API-5L-X52/X60 gas pipelines subjected to internal pressure, bending moment, and combined loading. The operating limit conditions as well as prototypal evaluation and sensitivity analysis results showed a promising applicability of the probabilistic integrity assessment program.