基于检验测试策略的PFD模型建立与分析*

为制定合理检验测试策略，提高安全仪表系统（SIS）在低要求运行模式下的安全性，提出要求平均失效概率(PFDavg)通用计算模型，引入检验测试分布因子和共因失效修正因子，表征部分和完全检验测试对SIS安全性的影响。结果表明:该模型适用于所有同构koon架构系统，可应用于周期性、非周期性部分检验测试及共因失效影响较大的场景，可以为企业制定检验测试策略提供理论依据。

Establishment and analysis of PFD model based on proof test strategy

In order to formulate the reasonable proof test strategy to improve the safety of safety instrumented system(SIS)in the low-demand operation mode,a general calculation model of the average probability of dangerous failure on demand(PFD_avg)including the partial and complete proof test was proposed,which was suitable for the isomorphic koon architecture SIS.The proof test distribution factor and the common cause failure(CCF)correction factor were introduced into the model,and the influence of partial and complete proof test on the SIS safety was reflected,so it can be applied in the proof test strategy including the periodic or non-periodic partial proof test.The model was applied to the assessment of the emergency shut-off valve subsystem,and the application results showed that the model was practical and feasible,and it can be used as an effective tool for selecting the cost-effective proof test strategy.