Strength And Stiffness And Fatigue Reliability Study Of Nuclear Safety Class 2 Bellows Globe Valve

In the context of low-carbon economy,nuclear energy will become one of the most promising new energy sources.As the connection pivot of the nuclear power plant systems,nuclear valve is the basic guarantee for reliable operation of nuclear power plants.In the normal operation of the nuclear power plants,due to the problem of reliability deficiency itself,the annual maintenance of costs of nuclear valve accounted for more than half of the total maintenance.Based on the problem of insufficient reliability analysis of nuclear valves,such as the limitations of the test conditions,the complexity of the test process and the risk of fatigue failure,etc.,Nuclear safety class 2 globe valve was used to carry out the following strength and fatigue reliability fatigue analysis.(1)According to the high reliability requirement of the nuclear valve,the standard system and material of the nuclear valve were elaborated,according to related standards,the strength of valve body was calculated and the wall thickness was checked;structural strength under tensile,extrusion,bending external load and seismic load was analyzed on finite-element method,to ensure its effectiveness in the process of analysis and design.(2)Based on the stress-intensity interference theory,the reliability model of the bellows was established.Using the theory of non-linear correlation,the two-layer bellows of the nuclear grade 2 bellows globe valve was analyzed under the condition of bearing only external pressure load,tensile load and under pressure.The influence of the gap and tensile load on the strength and fatigue life of the bellows structure had a certain guiding effect on the manufacture,use and fatigue life of the two-layer bellows.(3)On the basis of thermal-structure interaction coupled mathematical equations and boundary conditions,the transient temperature field and transient thermal shock analysis of the valve body in fully open state were used to improve the fatigue life of the nuclear valve,and provide a certain degree of guidance on how to effectively reduce the pressurized thermal shock effectively.