1. General classification and performance introduction of non-metallic gaskets

(1) There are many types of rubber products used for sealing by rubber sheets, generally natural rubber sheets, nitrile rubber sheets, neoprene rubber sheets, isobutyl rubber sheets, styrene butadiene rubber sheets, EPDM rubber sheets, and silicone rubber Plate, tetrafluoroethylene plate, fluorine rubber plate.

Natural rubber, nitrile rubber, and neoprene rubber are used in large quantities of rubber sheets for gaskets. In recent years, special rubbers such as fluorine rubber have also been gradually promoted.

(2) Non-asbestos board In recent years, with the strengthening of environmental protection requirements, asbestos products will show people's sight. Sealpilot non-asbestos board is a sealing material made by mixing organic and inorganic fibers with special glue series adhesives and a small amount of filler materials, and then rolling and vulcanizing. Because it does not contain asbestos fibers, it is suitable for non-asbestos replacement products for asbestos gaskets. Non-asbestos gaskets not only have high strength, but also have good resilience, and at the same time have super anti-permeability performance. The non-asbestos products of Bird Seal are good environmentally friendly materials to replace asbestos gaskets under high temperature and high pressure. .

(3) Asbestos rubber sheet Asbestos rubber sheet is made by pressing asbestos, rubber and filler. According to its different formulas, processes, properties and uses, there are mainly high-pressure asbestos rubber sheets, medium and low-pressure asbestos rubber sheets and oil-resistant asbestos rubber sheets.

There are chrysotile asbestos and blue asbestos (crocidolite) as the asbestos materials used to make asbestos rubber sheets. Chrysotile asbestos belongs to the serpentine type of asbestos. Its main component is magnesium silicate containing about 13% of crystal water. It has good heat resistance, alkali resistance, high tensile strength, and poor acid resistance. Most asbestos rubber sheets are Made by it. Blue asbestos belongs to the hornblende asbestos, the main component is silicate containing 2.5 to 3.5% of crystal water, magnesium oxide is very small, and iron oxide accounts for about 18 to 24%. Blue asbestos is not only good in heat resistance, but also in acid resistance, so it is mostly used to make acid-resistant asbestos rubber sheets.

The quality of asbestos fiber has a great influence on the performance of asbestos rubber sheet, so the asbestos fiber is required to have high tensile strength, good heat resistance, a certain length, and the fiber is easy to bend and be elastic. Generally, high-pressure asbestos rubber sheets and No. 400 oil-resistant asbestos rubber sheets use asbestos fibers of grade 2 and 3. At present, due to restrictions on the use of asbestos rubber sheets, more non-asbestos rubber sheets are used to replace the original asbestos sheets.

(4) Flexible graphite sheets and strips Flexible graphite is a novel sealing material with good resilience, flexibility, media resistance, and temperature resistance, and has been quickly promoted and applied in chemical companies.

(5) Polytetrafluoroethylene Polytetrafluoroethylene is the leader among synthetic resin materials. Excellent corrosion resistance makes it can be used as a sealing gasket in most of the strong corrosive media. It is especially suitable for industries such as medicine and food that do not allow materials to be polluted. It is a temperature-resistant material among plastic sealing materials. However, the PTFE material is easy to cold flow after being compressed, and it is easy to creep after being heated, which affects the sealing performance. Some glass fibers, graphite, and molybdenum disulfide are usually added to improve creep resistance and thermal conductivity.

(6) Other types of gaskets In order to solve the sealing problems in chemical production, Bird Seal also trial-produced some non-asbestos gaskets. A few examples are introduced as follows:

①Asbestos resin plate gaskets The acid-resistant gaskets cut from a soft plate-like material made of non-asbestos and polyvinyl chloride resins have high strength, good pressure resistance and relatively low price. The sample was boiled in 65% nitric acid for 1 hour, and the weight loss was 7.28%.

②Asbestos impregnated gasket It is a kind of shaped acid-resistant sealing gasket that is punched out of acid-resistant blue asbestos board and impregnated with acid-resistant paint.

After the above two gaskets are immersed in nitric acid and sulfuric acid and boiled tests, their weight loss and weight gain percentage are much lower than the acid-resistant asbestos rubber sheet.

③Asbestos woven gasket The asbestos rope is knitted into a flat shape, and the two ends are stitched together with asbestos rope. According to the use temperature, the asbestos materials are different. At present, domestic asbestos woven gaskets made of 60~70% blue asbestos and first-grade chrysotile asbestos are used in China, which can be used up to 800℃