China Safety Science Journal ›› 2025, Vol. 35 ›› Issue (12): 147-153.doi: 10.16265/j.cnki.issn1003-3033.2025.12.1701

• Safety engineering technology • Previous Articles     Next Articles

Structural reliability assessment of gas pipeline segments considering multiple defects correlation

PENG Weiyuan1,2(), PENG Shiliang1,2, CHEN Pengchao3, SU Huai1,2, ZHANG Hong1,2, ZHANG Jinjun1,2   

  1. 1 National Engineering Laboratory for Pipeline Safety, China University of Petroleum-Beijing, Beijing 102249, China
    2 Beijing Key Laboratory of Urban Oil and Gas Distribution Technology, China University of Petroleum-Beijing, Beijing 102249, China
    3 PipeChina Institute of Science and Technology, Tianjin 300457, China
  • Received:2025-07-01 Revised:2025-10-10 Online:2025-12-27 Published:2026-06-28

Abstract:

A structural reliability evaluation method for gas pipeline segments with multiple defects, based on Copula functions, was proposed to address the characteristics of the interrelationship between defects and the difficulty in quantifying the highly nonlinear coupling effects of multiple defects. First, based on the limit state equations of pipeline segments corresponding to different defects, Monte Carlo (MC) method was used to calculate the failure probability and probability distribution of pipeline segments under the influence of a single defect. Second, the probability distribution of each defect were treated as random variables, and the Copula functions were employed to study the impact of the correlation between different defects on the pipeline failure probability. The joint failure probability of the pipeline segment under the coupling effect of two defects was obtained. Third, the reliability of the pipeline segment with multiple defects was determined based on the second-order narrow-bound theory. Finally, using this method, the impact of the correlation between corrosion and crack defects on the structural reliability of gas pipeline segments was explored, and the variation of pipeline reliability was analyzed under different defect depths and wall thickness ratios (0.2-0.8). The results show that, under the condition that the failure probabilities of the defects are at the same order of magnitude and do not differ significantly, the correlation of the same type of defects is stronger, and the coupling effect has a greater impact on the pipeline failure probability. Compared with traditional series methods that assume independence between defects, which underestimate the pipeline reliability, the results of this method are more consistent with practical needs. This approach provides theoretical support for the stable operation of gas pipeline segments with multiple defects.

Key words: multiple defects, correlation, gas pipeline segments, structural reliability, reliability assessment, Copula functions, failure probability

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