Evaluation of Sealing Performance and FEM Calculations in Bolted Flange Connections With Ring Joint Gasket Subjected to Internal Pressure

The bolted flange connections with ring joint gasket have been used to seal the inner fluid at higher pressure under higher temperature condition. Assembly procedures and tightening methods for the type of gasket have typically been empirically determined. Generally, it is known that the bolt preload which is required to seal the inner fluid in the connections using the ring joint gasket is not higher than that of the connections using sheet gaskets and spiral wound gaskets. However, no research for the evaluation of sealing performance in the bolted flange connections with metal ring gasket has been conducted. In this paper, the leakage tests for the bolted flange connections with the ring joint gasket were conducted in the case where the maximum pressure is 10MPa. Measuring the leak rate of inner fluid using the pressure drop method, the sealing performance of the connections with the ring joint gasket was evaluated. In addition, using the FEM stress calculations, the flange hub stress distributions and the flange groove stress distributions were examined as the evaluation for the flange strength. As the result, it is found that the stress distribution at the contact surfaces between the ring joint gasket and the flange groove depends on the bolt tightening procedure. In the leakage tests, it was observed that the amount of the leakage (He gas) depends on the stress distributions at the groove stress which is affected due to the bolt tightening method.