Optimization Research On The Determination Of Safety Integrity Level In Functional Safety Analysis

With the rapid development of industrial civilization and the quick advance in industrial technology,security is getting more and more attentions.Functional safety technology plays an important role in the protection of personal,property and environmental safety.However,there are still some problems worth discussing in the standard for the rationality and effectiveness of the methods for determining the target safety integrity level.Therefore,establishing the methods selecting principle and analyze the influence of common cause failure on the risk analysis of the equipment under control with the background of functional safety standard,will have a very important practical value and reference significance to scientifically determine the target safety integrity level.In order to choose methods scientifically,a method which is adaptable for matching the equipment under control according to their features was presented after a comprehensive analysis of the applicability of the six common used methods as well as the safety characteristics of the equipment under control.Furthermore,the correlation strength between the analysis methods and the characteristic of the equipment under control was expressed by the case reasoning technology in the way of the matrix form of quality house to establish the matching mode.Additionally,there may be a common cause failure between the equipment under control and the safety-related system,so a fault tree analysis for the special accident that may be occur was conducted based on the qualitative screening of the 5M influencing factors.Then the Cut set operation was curried out to determine the common cause failure of the two separate systems.Finally,The reliability calculation method based on the fault tree was used to calculate the influence of the common cause failure on the target SIL.Finally,the method was respectively applied to the cases of “the coal pressurized gasification unit” and “the large-scale floating roof oil tank”,which shows the feasibility of the research.