Abstract
A Creep/relaxation occurs when gaskets for the flanged joints are used over extended periods. The Creep/relaxation of gaskets may causes leakage of an internal fluid from the flanged joints. A PTFE sheet gasket is easy to cause a creep strain of gasket and the stress relaxation of the flanged joints, and may causes leakage compared with compressed other gaskets. In the present study, the relationship between the sealing performance and the stress relaxation behavior is investigated in flanged joints using the gasket. The experiment is carried out using the PT Class 150, slip-on type and six-inch flanges and expanded PTFE sheet gasket, and the relaxation behavior of the bolts and leak rate of internal fluid is measured from the start time of the test to 240 hours at room temperature. The leak rate decreases with the decreasing relaxation behavior of the bolts. It is considered that ununiformly-distributed stress of test gasket right after the tightening relaxed with the time.
