内圧を受ける渦巻き型ガスケット付き管フランジ締結体の有限要素応力解析と特性評価

-管フランジ呼び径の影響-

抄録

This paper deals with the stress analysis of a pipe flange connection with a spiral wound gasket under an internal pressure using the elasto-plastic finite element method taking account the hysteresis and the non-linearity in the stress-strain curve of the gasket. The effects of the different nominal diameter of the pipe flange connections from 2”to 20”on the contact gasket stress distributions, the hub stresses and the load factors are examined. As a result, it is found that the variations in the contact gasket stress distributions are substantial due to the flange rotation in the pipe flange connections with the larger nominal diameter. It is observed that a difference of the hub stresses between the initial clamping state and the internal pressure application is small in the pipe flange connections. It is also found that the value of the load factor of the connections decreases as the nominal diameter of the pipe flange increases. The results by the analysis are fairly consistent with the experimental results concerning the variation in the axial bolt force. By using the contact stress distributions and the results of the leakage tests, the new gasket constants are evaluated. In addition, a method to determine the bolt preload for a given tightness parameter is demonstrated. The bolt preload obtained by PVRC is found to be smaller than that obtained using the load factor.