抄録
A gasket in flange joint experiences the both creep and stress relaxation by used for the long term. Recently, the creep property of gaskets at a room temperature was evaluated by a viscoelasticity model in single axis. But many gaskets are used at an elevated temperature, so the clarification of their creep properties at the elevated temperatures is urgently needed. In order to measure the creep and stress relaxation properties of gaskets at the elevated temperature, the test device was manufactured in which four-inch flanges were used. This paper describes the evaluations of the creep properties of non-asbestos compressed fiber sheet gaskets using a 3-D viscoelasticity model under the elevated temperature. The 3-D viscoelasticity model that yields more accurate results compared to the viscoelasticity model, which uses the conventional single axis, was applied to the elevated temperature creep properties. Using the3-D viscoelasticity model, the gasket creep is divided into the viscoelasticity component that converges on a certain strain and the volume change component that increases with time. The gasket strain is evaluated using the 3-D viscoelasticity model taking account the gasket stress relaxation. It is shown that the gasket strain is divided into the pure creep component of the gasket and the volume change due to the weight loss and chemical factor.
