中文摘要：

针对石化行业典型有毒介质和法兰连接的泄漏特点，采用连续点源泄漏扩散数学模型，以距点源任意距离处能构成危险的介质初始浓度为依据，计算了相应的源强浓度．在此基础上，对有毒介质进行了危险性分级，建立了石化行业典型有毒介质泄漏率分级方法，并依据危险性分级以及紧密性分级结果提出了相应的泄漏率等级．此种分级方法考虑到泄漏时的重要影响参数（介质特性、环境和气候因素以及泄漏源位置），并且建立了泄漏率等级与介质危害程度之间的关系，研究结果为密封连接的安全评价以及泄漏事故的预防和救援提供了借鉴．

英文摘要：

Aimed the characteristics of flanged connections and the toxic mediums frequently used in petrochemical industry, source strength density of the toxic mediums was calculated with continuous point source mathematical model and fuking the initial concentration of toxic mediums to make pernicious hazard at a certain distance away from the leak age source, the toxic mediums were classified. Furthermore, a classification of the toxic medium leakage rate in petrochemical industry was also proposed. This method considers medium characteristics, environment and climate factors, and leaking position, and the relation between leakage rate classification and endangered degree was obtained. The research results provide the reference for the safety assessment of sealed connections, the prevention and the rescue of leakage accidents.