Probabilistic safety assessment of the burst strength of corroded pipelines of different steel grades with calibrated strength models

This paper proposes an approach to assess the structural reliability of corroded pipes with calibrated strength models that reduce the subjectivity in model selection and incorporates their uncertainty. The approach calibrates and assesses the structural safety of pipes based on 25 burst strength models for corroded pipelines that are categorized into three classes of steel grades, i.e., low (X42 or less to X56), medium (X60 to X70) and high strength (X80 to X120). Statistical parameters such as the absolute mean error and standard deviation are adopted to analyse and compare the strength models’ performance against test results. Then, model uncertainties factors are derived and probabilistically characterized for each strength model. The importance of this methodology is demonstrated using a case study of one corroded pipe in each category of steel grade. The top 10 models from each steel pipe category are used for structural reliability evaluation. The First Order Reliability method is then employed for reliability and sensitivity assessments. Finally, partial safety factors are estimated by the best model in each steel category and compared with available codes. The proposed approach is believed to improve upon the existing methods by adopting the most accurate strength model and accounting for model uncertainties for different steel grades derived from test data and model predictions. © 2022