Abstract
It has been well known that a scatter in axial bolt forces in pipe flange connections tightened by the torque control method is substantial. In practice, pipe flange connections with the larger nominal diameter tightened by the torque control method have been used in chemical industry, and so on. In some study, the characteristics of the connections with smaller nominal diameter (less than 8") have been examined. So, in an optimum design of pipe flange connections with gaskets, it is necessary to understand the characteristics of the pipe flange connections with large nominal diameter under internal pressure and the contact gasket distributions due to the scatter in axial bolt forces in the connections tightened by the torque control method. In this paper, the experimental and FE analyses were done to evaluate the effect of scatter in axial bolt force on the gasket stress distribution and the sealing performance of pipe flange connections with 20" nominal diameter. Two types of torque controlled assembling procedures and an effect of scatter in the axial bolt forces obtained from the above methods is examined. Then, the effect of scatter in the axial bolt forces on the sealing performance of the connection is evaluated. The contact stress distribution in the larger pipe flange connection with 20" nominal diameter under internal pressure is analyzed using FEM by taking into account a non-linearity and a hysteresis. The measured scatter in the axial bolt forces is applied in the FEM calculations.
