When designing the flange thickness, should stiffness or strength of the joint be the main consideration?

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This post was last edited by “Kindergarten questions are too difficult” on May 10, 2019, at 13:03. As the title suggests, when designing the flange thickness, should considerations be given to the stiffness of the joint—that is, its sealability—or to the strength of the flange itself? From the perspective of flange strength: My calculation model and simplified model are shown in the figures. In view angle 2, the blue area on the upper surface of the flange is under fixed constraints, while the red area of the flange in view angle 1 is subjected to liquid pressure. Based on the stress conditions, the flange can be modeled as a beam as shown in the figures; it can be seen that the maximum combined stress occurs at the location under fixed constraints, which corresponds to the blue area on the upper surface of the flange in view angle 2, near the edge of the bolts. Therefore, it is sufficient to verify that the strength at this location meets the requirements. If not, the thickness of the flange should be increased (to enhance its bending stiffness) so that the material’s strength criteria are satisfied. From the perspective of sealing performance: The flange thickness that meets the strength criteria is selected and used for calculations to determine the pressure distribution across the gasket. Sealing performance is then evaluated in accordance with relevant sealing evaluation standards (such as PVRC), and it is determined whether an increase in flange thickness is necessary based on the required sealing grade.