Study On Quantitative Risk Assessment Of In-service Long-distance Natural Gas Pipeline Based On Failure Database

Nowadays, long-distance natural gas pipeline have stepped into a rapiddevelopment era in China. Until the end of2010, long-distance natural gas pipelinehave been forty-five thousand kilometers. With the rapid development oflong-distance natural gas pipeline, the safety problem has gradually emerged. It iscrucial that the ability of predicating accidents should be improved so as to realizeeffectively transportation. The purpose of study on quantitative risk evaluation ofpipeline is to improve the reliability in the process of natural gas transportation, toimprove the capability for accidents predication，to reduce the economic loss, injuriesand environmental destroy caused by accidents as little as possible. Therefore, it is ofgreat significance to study the quantitative risk evaluation of pipeline.According to the characteristics of long-distance natural gas pipeline in china，this paper analyses the main risk factors of pipeline, and studies the calculating modelof pipeline failure frequency that caused by different risk factors. In the meantime,this paper studies the gas release rate and failure consequence of different pipelinefailure mode, and a calculating method of risk value suitable for natural gas pipelinewas gave. In addition, the software used to evaluate quantitative risk was programmed.The following content are mainly considered：(1)A systematic analysis on the failure statistical data of the main oil and gasoperating country was introduced, which reveals the statistical law of pipeline failurein Europe, American and Canada.(2)The calculating model of natural gas pipeline failure frequency was developed,which can calculate failure frequency caused by internal corrosion, external corrosion,manufacturing defect and third-party interference.(3)According to the common mode of pipeline failure, this paper studiesreleasing and dispersing procession of releasing gas, and develops a simplecalculating model of pipeline failure consequence based on fluid mechanics. (4)This paper studies calculating model of individual risk, and develops acalculating analytic expression of individual risk. As a result, a criterion suitable fornatural gas pipeline and recommended acceptable risk level was given.(5)The software used to evaluate quantitative risk of long-distance natural gaspipeline was developed and was applied to a typical pipeline.(6)The method was compared with the kent’s. The result showed that it did nothave the three defects of kent’s.