Fragility assessment for process pipelines in flood events through physically-based hazard response analysis

Natech events triggered by floods have occurred frequently, resulting in physical damage to process equipment and subsequent releases of hazardous substances, threatening the operational safety of the process industry. Therefore, it is necessary to conduct flood fragility assessments on typical process equipment, such as storage tanks and process pipelines. Compared to storage tank, there are relatively few flood risk analysis methods applicable to process pipelines, and there is a lack of dedicated fragility models to quantify the probability of pipeline damage in flood hazard scenarios. Thus, this paper develops a process pipeline fragility model to support the quantitative risk assessment (QRA) of flood-induced Natech events more comprehensively. This model simultaneously considers the structural physical damage caused by internal pressure and external load in the pipeline and establishes the limit state equation (LSE) corresponding to the failure mode. On this basis, parametric fragility functions are trained using Monte Carlo simulations and logistic regression. A pipeline case is used to test the proposed fragility functions, and the results show that the fitted parameterized fragility model can sensitively capture changes in the failure probability curve caused by hazard intensity and pipeline characteristics changes. The proposed pipeline fragility model is applied to a composite area of pipelines and storage tanks, accurately assessing the failure probability of different types of pipelines in flood scenarios.