Strength Reliability Study Of High Temperature And High Pressure Multi-stage Decompression Control Valve

In the context of low-carbon economy, the development tendency of HTHP(high temperature and high pressure) valve is lightweight and high-performance. The problem of strength reliability is more evident under HTHP operating environment. Methods of predicting/evaluating trial sample of HTHP valve are rare, so reliability analysis and prediction methods have a barrier to cross.Aiming at the problem of reliability analysis of HTHP valves, such as the lack of maintaining records of longtime running, the limitations of the test conditions and the risk of fatigue failure, etc., HTHP multistage control valve was used to carry out the following fatigue analysis.(1) Based on FMECA(Failure Mode, Effects and Criticality Analysis) method, regulating system of HTHP multi-stage control valve except the driving device was analyzed. Components which mainly cause fatigue failure and analysis targets were determined. Stress-strength interference theory was adopted to establish a model of HTHP multistage control valve for reliability and theoretical life calculation; The effects of part size, surface processing, structural stress concentration on fatigue limit were analyzed, temperature correction coefficients were introduced to correct fatigue limit under high temperature to make the analysis results more accurate.(2) The 3D model of control valve was built with Pro/E software, and FEM software ANSYS Workbench was used to carry out thermal-structure interaction analysis. The dangerous parts equivalent stress of the parts was found out. According to the simulation results and control valve reliability theory model, reliability of each part and life under required reliability were calculated.(3) On the basis of thermal-structure interaction analysis, fatigue life of parts was analyzed based on the S-N curve. Fatigue life of main pressure components of HTHP multistage control valve was gained. By analyzing the fatigue life of the various components sensitivity curve, the effects of various components on valve system fatigue strength failure were gained. And then the parts which affect more would be optimized and overhaul during design stage and using stage.The researches above provide an indication of valve strength reliability.