Volume 21, Issue 1 (January 1993)
Asbestos-Free Gasket Materials for Turbines
The results of a systematic program undertaken to evaluate potential substitute materials for asbestoe-free gaskets used in power plant turbines are reviewed. Thirty-three commercially available materials were subjected to a series of tests reflecting the requirements of a good gasket material for turbine applications. The results identified flexible graphite as the only material to meet or exceed the properties of asbestos gaskets. One limitation of flexible graphite uncovered in the program, however, is its relatively high stress relaxation behavior especially at temperatures above 650°F (343°C). Ten-thousand-hour stress relaxation tests were conducted in the temperature range of 500 to 850°F (260 to 454°C) to determine the usable temperature limit of flexible graphite. The effects of joint flexibility and reloading were also evaluated at high temperatures.