Non-Asbestos Rubber Sheet containing chloride and sulfide, easy to form after the metal flange corrosion of the original battery, especially oil Non-Asbestos Rubber Sheet sulfur content higher than ordinary Non-Asbestos Rubber Sheet several times, so in non-oily media should not be used. Gasket in the oil and solvent-like medium will occur in the swelling phenomenon, but within a certain range, the sealing performance of the basic no effect. For example, No. 400 oil-resistant Non-Asbestos Rubber Sheet in the room temperature aviation fuel for 24 hours soaking test, requiring the increase in oil weight shall not exceed 15%.
Domestic Non-Asbestos Rubber Sheet and foreign brand-name products are still a certain gap. A unit of statistics shows that in more than 350 ℃ of oil medium, where the use of Non-Asbestos Rubber Sheet does not leak most of the imported products. Japan Petroleum Industry Standard JPI-7S-71 "Standard for the use of Non-Asbestos Rubber Sheet for petroleum industry" with a term of about one year.
(3) Teflon PTFE in the pressure and high temperature easy to cold flow and creep, it is generally used for low pressure, medium temperature, strong corrosion and not allowed to contaminate the media, such as strong acid, alkali, halogen, drugs Wait. Safe use of the temperature at 150 ℃, the pressure below 1MPa. Filled polytetrafluoroethylene, although the strength of higher, but the use of temperature does not exceed 200 ℃, and corrosion resistance decreased. Polytetrafluoroethylene package pad maximum pressure is generally not more than 2MPa.
As the temperature increases, the material creep, resulting in significant reduction in sealing pressure. Even if not heated, with the extension of time, the sealing surface of the compressive stress will decline,Non-Asbestos Rubber Sheet resulting in "stress relaxation phenomenon." The phenomenon will occur in a variety of gaskets, but the stress relaxation phenomenon of polytetrafluoroethylene pad is more serious, Should be noted.
Teflon friction coefficient is small (compression stress greater than 4MPa, the friction coefficient of 0.035 ~ 0.04), preload when the gasket is easy to slip out, so it is best to use concave and convex flange surface. When the use of flat flange, the gasket can be outside the contact bolts,Non-Asbestos Rubber Sheet the use of bolts to prevent the slide outside the slide. As the glass-lined equipment is sprayed on the metal surface of a layer of enamel after sintering, glaze layer is very brittle, coupled with uneven spraying and glaze flow, flange surface flatness is poor. The use of metal composite gasket is easy to damage the glaze layer, it is recommended to use the core material from the asbestos board plus rubber PTFE packing. This pad is easy to fit with the flange surface and corrosion resistance, the use of good results.