抄録
In the present paper, the characteristics of the metal flat gasket and the flange connection with metal gasket were examined experimentally at room temperature. In addition, the sealing mechanism of the metal-metal contact gaskets was studied. The gaskets used were fabricated by aluminum, copper and Cr-Mo steel flat gaskets. Firstly, according to JIS B 2490, the effects of the gasket materials, surface roughness and gasket width on the sealing characteristics of the above metal flat gaskets were measured. That is, the gaskets were compressed using a material testing machine while the leakage was measured. The relationship between the compression stress and the amount of leakage was obtained. In the metal-metal gasket contact region, it was found newly that the amount of leakage depended on the gasket yield stress because the contact surfaces increase due to the surface roughness. The amount of leakage was found to decrease rapidly when the plastic deformation occurs at the contact gasket surfaces. In addition, the amount of leakage was measured for bolted flanged connections (flange nominal diameter: 2”) with metal gaskets. Furthermore, the contact gasket stress distributions in the connection were analyzed using 3-D FEM analysis. Using the obtained results from the FEM stress analysis, the characteristic of bolted flanged connections with metal flat gasket was elucidated. The estimated result were fairly good agreement with the measured results. It is found that when the plastic deformation occurs at the contact gasket surface, the sealing performance increases substantially.
