The Reliability Analysis To Spring Full-open Safety Valve By FMEDA Method

The spring full-open safety valve is a widely used over-pressure protection device and its reliability directly affects safety and economic benefits.There are three difficulties for spring full-open safety valve in determining the inspection cycle and the reliability of quantitative analysis.1)Due to the industrial internal failure data samples are often too small,there is a high proportion of accidental factors when quantitative analysis depends on the reliability on their own data.2)The safety valve parts failure rate has varied greatly due to differences in usage and changes in the environment and it is difficult to obtain.;3)The factors affecting the service performance of the safety valve is complicated,so the the safety valve test cycle is difficult to determined quantitatively.The following research work has been carried out:(1)In order to obtain a more accurate in-service safety valve failure rate,as a means of solving the problems of using database data on reliability analysis,this paper presents a failure rate calculation method which is based on Bayesian estimation.(2)On the basis of achieving the safety valve failure rate through the study of the relationship between the safety valve failure modes and causes,combined with expert experience knowledge using analytic hierarchy process(AHP)to calculate the safety valve parts failure rate of the proportion,to calculate the safety and dangerous failure rate value of the safety valve,improve the FMEDA technology based on analytic hierarchy process,and set up a FMEDA prototype analysis software,it provides a new thought to the difficult problem of analyzing the failure mode due to the lack of component data.(3)For the petrochemical processing industry needs to run for long periods of time,there is a need to extend safety valve inspection cycles from the perspective of the semi-quantitative and quantitative perspective,using five kinds of methods to determine safety valve inspection cycle.Comparing the results of each method in determining the inspection cycle analysis provides a reference for the determination of safety valve inspection cycle for the long term running of petrochemical device.The FMEDA analysis technology is based on the analytic hierarchy process to research the reliability of the safety valve,in order to get the valve parts failure rate and find out the weakness of the safety valve.In addition,it simultaneously puts forward the improvement measures,and provides data support for the semi-quantitative and quantitative method of determining the safety valve testing cycle.This is consistent when comparing the inspection cycle calculated in this paper to the results of petrochemical industry operating experience and inspection agency of the assessment report.It also verifies the validity of the method to determine the test cycle and the availability of FMEDA analysis technology based on the analytic hierarchy process,so the methods has practical significance.