Study On Risk Assessment Method Based On Fault Tree Analysis In Long Pipelines

Accidents in pipelines have occurred frequently in the past period of pipelines transporting development.Pressure Pipelines safety situation is stern.Public tolerance is now decreasing.Therefore,Risk reduction in hazardous pipelines is more and more important,such as:improvement of management system,reliability and risk analysis.The analysis of major accidents in hazardous pipelines underlines how the systematic control of the hazards involved is essential for prevention purposes. Identification of pipeline hazards associated with the different pipeline system functions is essential for risk analysis and historical data are of great importance.In the light of pipeline accidents occurred in Russia,Europe and the US,during 70's-nearly 90's,an analysis has been carried out,with the aim of full understanding the accidents and accidental causes as to provide a referential experience for the daily operation in the type elementary division of pipeline.Distinction should be made between several categories of pipelines e.g.gas and hazardous liquids pipelines, sincethe associated risks are of different nature and level.It is also important to distinguish between risks associated with different functions of pipeline systems.FTA(Fault Tree Analysis) is an effective method to evaluate the reliability and security of large complex system.Using this way,the failure of oil and gas pipeline sis discussed.The fault tree of oil and gas Pipelines is established by considering two major failure modes of pipelines:leaking and rupture.All the minimal cut-sets are got through qualitative analysis.The basic risk factors are investigated that cause failure of pipelines.Fault Tree is also a model that quantitative analysis is based upon.In the fault tree quantitative analysis of oil and gas pipelines,due to lacking of the enough test-data and field-data,the fuzzy mathematics analysis method is introduced.Triangular fuzzy-numberdesignated probability of the basic events in fault tree.A method-Median method for analyzing fuzzy significance was provided to order the basic events in fault tree.The process of calculation and steps were presented in detail.The fuzzy probability order and classification are also found.The method given in this article is a new way to treat fuzzy failure probability of events in oil and gas pipelines.Oil and gas pipelines can be regarded as a grey system for its characteristic and grey theory,Grey correlation analysis is applied in the model identification of the fault diagnosis and fault tree analysis.The possibility of fault model could be judged correctly in the fault tree analysis,which provides a scientific basis for fault handling in order to improve the reliability and security of the system.The paper is concluded with the point of view.Detailed distinction should be made between pipelines;the different fault tree should be established according to different pipelines and different part of pipeline;appropriate quantitative analysis based upon fault tree should be applied;a scientific and dada bases should be set up for manager.