Numerical modelling of an air operated valve assembly for virtual diagnosis based on experimental diagnosis in nuclear power plants

The valve assembly used in many industrial plants is important safety-related equipment. Diagnosing a valve assembly is important because the failure of a valve assembly can lead to severe safety problems and financial loss. This study conducted an experimental diagnosis and numerical diagnosis of a balanced globe valve with an air operated piston actuator. Using experimental diagnostic data, the physical properties were calculated and applied to a multibody dynamic model using various forces that affect the moving mechanism, such as spring force, sealing force, packing force, and supplied air force. The numerical model was created by applying multibody dynamics to the geometric and material information of the valve assembly. Because the numerical model is based on measured physical properties from the experimental diagnostic data, and verified by the experimental stroke and the numerically calculated stroke, the numerical model satisfies the concept of a test-based methodology which is required in the new specifications of ASME QME-1 2017. The numerical model can be used as a diagnostic tool, for functional qualification, as a tool to monitor aging conditions as time passes, and a maintenance tool in industrial sites.