The application of asbestos rubber sheet in the valve sealing industry has the following advantages:

Low price: Compared with other high-performance sealing materials, the price of asbestos rubber sheet is more affordable.

Chemical resistance: Asbestos rubber sheet has good corrosion resistance for some medium with relatively mild chemical properties, which can meet the needs of general working conditions.

Easy maintenance: Because the asbestos rubber sheet is easy to process and replace, it is more convenient for the maintenance  of the valve.

The biggest problem of asbestos rubber sheet is that although the gasket material is added with rubber and some fillers, it is still unable to completely fill the tiny pores that connect, and there is trace penetration. Therefore, in the highly polluting medium, even if the pressure and temperature are not high, they can not be used. When used in some high-temperature oil media, usually in the later period of use, due to the carbonization of rubber and filler, the strength is reduced, the material becomes loose, and there is penetration at the interface and inside the gasket, and there is coking and smoke. In addition, the asbestos rubber sheet is easily bonded to the flange sealing surface at high temperature, which brings a lot of trouble to the replacement of the gasket.

In the heated state, the pressure of the gasket in various media depends on the strength retention rate of the gasket material. There are crystal water and adsorbed water in asbestos fiber material. At 110℃, 2/3 of the adsorbed water between the fibers has been precipitated, and the tensile strength of the fibers is reduced by about 10%. At 368℃, all the adsorbed water precipitates out, and the tensile strength of the fiber is reduced by about 20%. Above 500 ℃, crystalline water begins to precipitate, and the strength is lower.

Asbestos rubber sheet contains chloride ions and sulfide, easy to form corrosion galvanic cells with metal flanges after water absorption, especially the sulfur content of oil-resistant asbestos rubber sheet is several times higher than that of ordinary asbestos rubber sheet, so it is not suitable for use in non-oily media. Gaskets will swell in oil and solvent media, but within a certain range, there is basically no impact on the sealing performance.

However, it is important to note that asbestos has been identified as a hazardous substance, and the use of asbestos rubber sheets may present potential risks to health and the environment.