Comparison of performance for non-asbestos and asbestos seat gaskets

摘要

As pure PTFE and expansive graphite are hopeful as the material of non-asbestos seat gaskets, the comparison with the performance of asbestos seat gaskets are carried out for one of non-asbestos seat gaskets. They have the same size in dia. and the thickness of 1.0, 1.5, 2.0 and 3.0 mm respectively. The items of the test are the maintenance "m" factors and yield "y" stresses. The test pressure with the nitrogen gas are 2.06 MPa and 0.014 MPa respectively. The "m" factors of 1.0, 1.5 and 2.0 mm thickness of PTFE and graphite seats have the constant figures of about 10 and 25 respectively without depending on thickness. The "y" stresses of them also have about 12 MPa and 3 MPa respectively. But the figures of both gaskets of 3.0 mm in thickness have different ones so that they may be depended on thickness, if it would be over 2.0 mm. And it was confirmed that the "y" stresses of asbestos seats by gas fluid are remarkably exchanged with thickness. Though the performance of graphite seat gasket is a little inferior in "m" factor and the "y" stresses of PTFE of 3.0 mm in thick is little high, PTFE and graphite seat gaskets can replace asbestos one with the select of temperature, corrosive fluid and so on in consequence of the result.