Overall reliability analysis on oil/gas pipeline under typical third-party actions based on fragility theory

Based on fragility and internal & external hazard, an overall reliability model can be established as a theoretical basis for quantitative risk assessment on oil and gas pipeline systems. In this paper, overall reliability is regarded as conditional probability, including probability of third party hazard and pipeline fragility. Third parties refer to all individuals, organizations and mechanical tools that cause unexpected damages to pipelines when they are carrying out operations either relevant or irrelevant to pipelines. By analyzing the propagation, waveform and frequency spectrum of natural seismic waves, the acceleration waveform of an artificial seism is simulated. Also a finite element model of pipeline's seismic response is established. Various pipelines' reactions simulated by ANSYS software are analyzed. Then the fragility probability of pipelines under blasting seismic actions is determined by normal distribution model. The overall reliability model is established and quantitatively evaluates the risks of Petro-China Gang-Zao product oil pipeline. By comparing the calculation results from algorithm software with the actual situation, the confidence interval of this model is [95%,100%]. This model can precisely calculate the risk probability of certain pipe sections and then decide which section should be preferentially maintained and protected, increasing the efficiency of pipeline management. (C) 2016 Elsevier B.V. All rights reserved.