抄録
This paper deals with the effects of the nominal diameter of a pipe flange connection with a non-asbestos spiral wound gasket under an internal pressure on the mechanical characteristics such as the contact gasket stress distribution which governs the sealing performance, the load factor and the hub stress of the connection. The stresses in the pipe flange connections with the nominal diameters from 3”to 24” under internal pressure are analyzed using finite element method taking account the hysteresis and non-linearity in the non-asbestos spiral wound gasket. 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. Leakage tests were conducted to measure the axial bolt forces (the load factor) and the hub stress. The results obtained from the FEM analyses are fairly consistent with the experimental results concerning the variation in the axial bolt forces (the load factor) and the hub stress. Using the obtained contact gasket stress distributions and the fundamental relationship between the amount of leakage and the gasket stress, the amount of the leakage of the pipe flange connection is estimated. The estimated results are in a fairly good agreement with the measured results. The difference in the hub stress between the FEM and ASME code is demonstrated and the sealing performance of the non-asbestos gasket is discussed.
