The Risk Assessment Of Gas Pipeline Leakage Emergency Repair

Gas pipelines may leak due to corrosion,aging,construction damage,engineering quality and other reasons during operation.After the Leakage accident,it needs to repair immediately.As a result of emergency workers peccancy operation,repair equipment failure,repair operation conditions,the repair company management defects,repair process may lead to explosion,casualties and other accidents.Thus the risk assessment about repairment has important engineering practical value.In this paper,Gambit software is used to establish a two-dimensional leakage diffusion model about buried pipeline and then the model is imported into FLUENT software.The FLUENT software which is based on fluid mechanics and porous media theory is used to set the boundary conditions and related parameters of the model.Using FLUENT software simulates and analyzes the gas diffusion law in the soil under the six working conditions.The pipeline pressure is 0.1MPa and the leakage aperture is 5mm,8mm and 10 mm namely.The leakage aperture is 10 mm and leakage pressure is0.1MPa、0.15 MPa and 0.2MPa namely.Based on the results of the "risk factor survey" questionnaire,a secondary risk evaluation index system is established.The first-level indicators are composed of risks from personnel,equipment,material,technology,environment and management.And the secondary indicators are 28 specific risk factors from the first-level indicators.As the risk factors are many and complex,analytic hierarchy process(AHP)is adopted to solve the weight of each index.A judgment matrix which is based on the results of the questionnaire survey about the importance of risk factors is constructed.The eigenvectors of the matrix are solved and normalized as the weight values of each index.Based on the fuzzy characteristics of six types risks in the process of emergency repair,a fuzzy comprehensive evaluation method which is suitable for the process of emergency repair is proposed.The method uses fuzzy algorithm to realize the quantitative treatment of each risk and can comprehensively reflect the magnitude of risks in the process of emergency repair.Taking the emergency repair process of a gas pipeline leakage as an example,the fuzzy comprehensive evaluation method is used to evaluate the risk.It is concluded that there are high risks in the emergency repair which are company’s rules and regulations,staff’s teamwork ability and staff’s safety responsibility consciousness.Finally,according to the results of risk assessment,some measures to reduce risks are put forward,such as establishing rules and regulations,increasing the number of emergency drills and strengthening safety education of emergency repair personnel.