Study On Leakage Risk And Control Measures Of Yuantuogou Section Of Lanzhou Station

With the rapaid increase of city development, more and more populations and buildings are concentrated in the area where oil pipelines pass through. The risk assessments and control measures of Yuantuomaogou oil pipelines which pass through densely populated areas can effectively reduce the casualties and econmic losses which caused by failure accident. This thesis is mainly carried out the following aspects of Yuantuomaogou oil pipelines based on risk assessments and control measures.(1) According to the investigation of Yuantuomaogou oil pipelines, the analysis results of oil pipelines inner inspection and cathodic protection effectiveness, the fault tree which composed of 49 basic events is established. By analyzing minimum cutsets and structure importance coefficients of fault tree, the following conclusion comes out:Corrosion is the most major failure factor of Yuantuomaogou oil pipelines.(2) According to the evaluation standard of Risk assessment for Buried Steel Pipeline and Pipeline Risk Management Manual, the failure possibility index system of Yuantuomaogou oil pipelines is established, which is composed of 77 grade item. On basis of fuzzy mathematics theory and 5 evaluation index score interval grades, the failure probability calculation method is proposed.(3) Leakage failure consequence models of Yuantuomaogou oil pipelines are ascertained by event tree analysis. Leakage simulation model is established by OLGA software and banded pool fire affected area calculation method is proposed. Quentitative calculation models of probability and influence area are established respectively, which include banded pool fire, vapour cloud explosion and flash fire. On basis of TOPSIS standardization and Euclidean parameter, failure consequence assessment method of casualties and economic losses is given.(4) According to the failure possibility and failure consequence, the risk level is divided into 4 grades by risk matrix method. The risk assessment model of Yuantuomaogou oil pipelines is established and the assessment process is introduced briefly. By the risk assessment model established in this paper, Lanzhou-Chengdu-Chongqing product oil pipeline, Lanzhou-Zhengzhou-Changsha product oil pipeline and Lanzhou-Chengdu crude oil pipeline are assessed as relatively high risk level, which failure probability values are identified as 3.24×10-2,2.10×10-2,2.02×10-2 and failure consequence values are identified as 0.7906,0.7717,0.7416.(5) According to the results of risk assessment, appropriate risk control measures to reduce failure possibility and failure consequence are proposed. Graded accident is evaluated by leakage and the classification preplans are established.