New development in studies on the characteristics of bolted pipe flange connections in JPVRC

This paper deals with some studies carried out in the bolted flanged connection committee (BFC) in Japan Pressure Vessel Council (JPVRC) on the stress analysis of a pipe flange connection using the elastoplastic finite element method. The characteristics of the connections with the different nominal diameters from 2 in. to 20 in. such as the contact gasket stress distribution, the hub stress, and the load factors were examined. The results from the finite element analyses were 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 test, the new gasket constants were evaluated. As a result, it was found that the variations in the contact stress distributions were substantial due to the flange rotation in the pipe flange connections with the larger nominal diameter. A method to determine the bolt preload for a given tightness parameter was demonstrated and the difference in the bolt preload between our research and PVRC was shown. In addition, the characteristics of pipe flange connection under a bending moment and internal pressure were also discussed and a newly developed bolt tightening method was demonstrated.