Study On The Risk-assessment Technology Of Long Gas Pipelines

The growing demand of long gas pipelines makes the security and reliability problem of in-use pipelines attract more and more concern. The risk assessment and early warning of long gas pipeline system can effectively prevent sudden exploding and leaking events. Based on the analysis of overseas theory and technology and consideration of China present practice, the thesis analyzes the main factors leading to pipe problems, establishes the risk-assessment flow model and risk-assessment index system. The thesis adopts the fuzzy-index assessment method systematically and early in the study of pipeline's failure probability. It also proposes "fuzzy-index assessment method" of the long gas pipeline's failure probability and describes in great detail the method and the standard of defining indexes' value about pipeline failure. Then, it establishes half-quantitative computation model of the risk-assessment of long gas pipeline on the basis of analyzing the pipeline's failure probability and failure consequence.Firstly, the paper introduces fault-tree assessment method, establishes the threat-discerning fault tree of long gas pipelines, and finds out the main factors leading to the pipeline failure. By analyzing these factors, the thesis establishes the risk-assessment flow model and risk-assessment index system suitable to our country's practical situation.Secondly, the paper, by drawing on the experience of W.Kent Muhlbauer's pipeline risk assessment method and the fuzzy integrative assessment method, proposes the failureprobability assessment method of long gas pipelines-"fuzzy index method"(FI). In thismethod, AHP is taken to confirm the weights of the experts' sights. As an effort of being accurate and practical, the method of pre-giving experience value is used in obtaining the rank weight matrix and the method of using cut set of fuzzyαis used in obtaining the rank assessment matrix.Then, the method of pipeline's relative failure consequence and relative risk assessment is explained carefully. The thesis analyzes the factors influencing the long gas pipeline's failure consequence, and evaluates the pipeline's failure consequence with the method of half-quantitative assessment. In this method, the calculation model on the long gas pipeline risk assessment is proposed, and the long gas pipeline's relative risk result is got.At last, "the long gas pipeline risk-assessment software" is researched and developed. It can standardizes the management of long gas pipeline's failure information database and improves the efficiency of risk assessment, and provides theoretical and technical support for the long gas pipeline's safe and efficient running.