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STRUCTURAL STRESS ANALYSIS ON THERubber diaphragmOF AIR-OPERATED
VALVEAir-operated valves are used extensively in the power-generation industry for process control and system isolation functions. A study on the prevention of damage of an air operated valve is very important. Specially,Rubber diaphragmin an actuator of an air-operated valve has the highest damage rate.In this study, the stress ofRubber diaphragmwith thickness change is analyzed. For this analysis, four experiments were conducted to obtain material properties of rubber. A stress analysis is carried out by commercial FEM code, ANSYS 8.0.
It is compared with tension test to verify finite element analysis. From the result of analysis, the maximum stress happened at flange edge part, and the maximum displacement happened between flange edge and spring support. This study also finds out effect of the thickness about variable thickness. Even if a section area is same, the maximum stress is varied with the thickness of edge side.1.IntroductionAir operated valves are used extensively in the power-generation industry for process control and system isolation functions. Nuclear power plants consist of many air-operated valves. Safety is a primary issue in a nuclear power plant.
A study on the prevention of failure of an air-operated valve is very important. The most critical and sensitive component of the air-operated valve is the diaphragm. This provides the seal that allows a successful actuation to overcome spring pressure that is used to return the valve to its"safe" position.Table 1 shows failure cases of air operated valves. Table 1 is referred to "Air-operated valve maintenance guide"[l]. From the Table.1, 30% of total damage is failure of actuator.
Of actuator failures, the highest failure (35%) wasRubber diaphragmfailures, the second failure (29%) was seal and seal, the third highest failure (13%) was bolting- related failures, and next (4%) was piston binding.
In this study, structural stress analysis on theRubber diaphragmis carried out by commercial FEM code.