Elevated Temperature Characterization of Flexible Graphite Sheet Gasket Materials

To better understand the performance of flexible graphite sheet gaskets, a Pressure Vessel Research Council (PVRC) sponsored program has been launched in 1991, and extended in 1992-93 by the participation of a private gasket manufacturer company. The elevated temperature behaviour of these materials with and without different types of metallic reinforcement and/or passivating corrosion and oxidation inhibitor has been evaluated according to specific room and elevated test procedures and gasket quantification tools developed for the Material Testing Institute (MTI) and the PVRC.

The program consisted in combinations of short to long term (up to 6 months) mechanical screening tests at temperatures from 650°F to 1100°F. The test results are used to compute creep/relaxation resistance, thickness change, weight loss, density change and post aging tensile strength of gasket specimens subjected to the various aging conditions. To further check the correlation between mechanical properties and leakage behaviour, short term elevated temperature leakage tests were performed at specific test temperatures.

This paper presents a summary of the test results obtained and the development of quantification tools for flexible graphite sheet materials that permits the assessment of their probable long term performance in service.