Nonlinear Fuzzy Comprehensive Evaluation Method Of Long-distance Gas Pipeline Failure,

Accidents in the past pipeline transportation development have a high occurring rate, including malignant accident, and the consequences including economic damage and casualties were severe which caused strong social response. Accordingly,the developing and perfecting of some techniques is needed urgently, and make use of these techniques in the risk assessment of pipelines.The analysis of the pipeline failure event type and consequences emphasizes the prevention is the most important in how to effectively control involved risk.The main point in pipeline risk analysis is to conduct risk identification and confirmation in different pipeline system on the bases of the analysis of the historical accident data. This text makes a detailed description for risk assessment for long oil&gas pipelines, including the characteristics composition and accident situation of long oil&gas pipelines. And the general principles to choose risk assessment methods and the several risk assessment methods are also given in this paper,and then the method to judge the effect probability and to evaluate the consequences are given,too.Fault tree analysis is a technique which suitable for reliability and safety analysis in large and complex system.This paper eatablishes fault tree for long oil&gas pipelines on the bases of the fault tree qualitative analysis principle, and gets the minimum cut set, and then does quantitative calculation to the fault tree, finally gets the probability importance degree and critical importance degree of the basic reason event, and then recognizes the main influencing factors which causing pipeline failure. Essentially, fault tree analysis is a qualitative model which can conduct quantitative calculation easier, so it can be used to conduct quantitative risk analysis in pipeline.Because of the lack of enough field data and experimental data in long oil&gas pipelines, fault tree analysis is seemed not enough to use, so fuzzy comprehensive assessment model is usually used to the analysis in long oil&gas pipeline system. And as linear fuzzy assessment model can not response the prominent effect of some factors, so the innovation point in this paper is using a nonlinear fuzzy comprehensive assessment model to analyse long oil&gas pipeline system, and the assessment results are more tally with the actual which provides a new way of thinking to minimize the number of oil&gas pipeline failure problems.The standpoint of this paper considers:for the failure problem of long pipelines, first conduct qualitative analysis on the basis of the exist data and experience, set up the independent and simplified fault tree for each pipeline, and then do quantitatively calculation, find out weak pipeline, risk factors and the size and sorting of dangerous degree of the basic events which shoud be pay attention to in improving system reliability, provide theoretical basis of specific data in pipeline management operation.