Statistical Evaluation of Stress Independence of Two Connected Structures
In ASME B16.34, features included in a control valve geometry that allows connection to standard flanges, referred to as “flange like features”, need to be evaluated as part of the valve design analysis. An analysis approach is presented that evaluates if the stress in the region of the flange like feature is independent of the core control valve structure. When determined to be independent, then the flange like feature can be designed by rule using ASME B16.5. The approach evaluates the stress around the flange like feature with the flange at the designed location and then at an increased distance from the core control valve structure. Because the two geometries result in two different finite element analysis (FEA) meshes, a statistical approach was developed to evaluate how much the linearized stress behind the flange changes between the two different geometries. The result is a procedure and criteria to determine if the flange like feature can be designed by rule or further stress analysis is needed.