Progress in Gasket Testing—Milestone Results

An extensive gasket test program, carried out under the auspices of the Pressure Vessel Research Committee and supported by over 30 sponsors from 6 countries, is nearing completion. The program was developed as part of the Long-Range Flanged-Joint Improvement Program of the PVRC at the request of the American Society of Mechanical Engineers and in response to the need for resolving complex gasket behavior questions. The test program was formulated in cooperation with cognizant ASME, API and ASTM Standards Committees. In these tests, complex load/pressure sequences are used to determine leakage performance and deformation response at room temperature of four types of commonly used gaskets. This paper presents an overview of the test program which investigates the effect of fluid pressure, type of fluid, flange facing surface finish, maximum gasket stress, gasket deformation and stress cycling. The results of the first two series of tests on spiral-wound asbestos-filled gaskets are presented to highlight some of the trends observed. Interpretation of the results is carried out with the aim of deriving meaningful design factors similar to the m and y factors of the ASME Pressure Vessel Code. It is shown, however, that such factors cannot have a unique value for a given gasket type. Instead, m and y are interrelated and their value depends on the level of specified tightness. They are also influenced by the various parameters aforementioned.