Seal gasket types and their scope of application

All types of machinery and equipment, especially various types of pressure vessels, pipes and valves, etc., commonly use gasket sealing structure. The simplest gasket is a flat gasket. The entire gasket is made of the same material and used as the static seal of the general joint surface of mechanical equipment, such as the seal of a gear box.

The ideal gasket structure should be plastic as the surface layer, and the inner layer is an elastomer. The plastic surface layer guarantees sealing and close to each other even fit. The inner layer allows to compensate for a little separation of the sealing surface and often maintain a certain size on the seal. The compressive stress. Many combinations of gaskets are based on this idea or slightly modified, but the principle is the same. For example, polytetrafluoroethylene (PTFE) has good plasticity, excellent chemical resistance and a wide working temperature range (-190 to 250°C). It is commonly used for static seal flat pads, but for some reason it has poor resilience. And the tendency to cold flow restricts the simple use, and the use of a combined structure can overcome this drawback. On the one hand, it can protect the gasket from fluid medium corrosion or contact with food and pharmaceutical industry products, and on the other hand, it can improve the pure use of PTFE. Poor rebound and cold flow problems.

Non-metallic gasket type, material and applicable range

Gasket type Material pressure
MPa Temperature °C Applicable medium PTFE gasket PTFE plate ≤3.0 -108～250 Concentrated acid, alkali, solvent, oil rubber asbestos gasket High pressure rubber asbestos board Medium pressure rubber asbestos board Low pressure rubber asbestos board ≤6.0
≤4.0
≤1.5 ≤450
≤350
≤200 Concentrated acid, alkali, solvent, oil resistant rubber asbestos board ≤4.0 -180～250 Air, compressed air, inert gas, steam, ammonia, shift gas, coke oven gas, pyrolysis gas, water, seawater, liquid ammonia, Condensate, ≤90%** (mass fraction), salt, liquid ammonia, ammonia, liquid, caustic soda, freon, hydrocyanic acid, caprolone production media, polystyrene production media combination seal Pad type, material and application range Gasket type Material pressure
MPa Temperature °C Suitable for medium wound gasket Gasket: Stainless steel Non-metallic tape: Asbestos tape,
Teflon tape,
Flexible graphite with ≤ 6.4 ≈ 600 metal flat gasket for internal combustion engine Waveform pad Metal: soft steel, aluminum,
Stainless Steel, Alloy Steel Non-Metal: Asbestos Sheet, Rubber Asbestos Sheet, Teflon Sheet, Ceramic Fiber ≤ 6.4 ≈ 600 Steam, Hydrogen, Compressed Air, Natural Gas, Cracked Gas, Shift Gas, Oil, Solvent, Residue, Wax Oil, oil slurry, heavy oil, propylene, caustic soda, molten salt heat carrier, acid, alkali, salt solution, liquefied gas, water

Type, material and application range of metal gasket Gasket type Material pressure
MPa Temperature °C Applicable medium metal flat gasket metal toothed pad mild steel, stainless steel, alloy steel ≥ 4.0 ≈ 600 steam, hydrogen, compressed air, natural gas, cracked gas, shift gas, oil products, solvent, residual oil, wax oil, Slurry, heavy oil, propylene, caustic soda, molten salt contained love body, acid, alkali, alkali solution, liquefied gas, water metal octagonal cushion metal lens pad metal oval pad 10 steel, 1Cr13, alloy steel, stainless steel, etc. ≥ 6.4 ≈ 600 Steam ,Hydrogen,Compressed Air,Natural Gas,Cracked Gas,Conversion Gas,Oil Products,Solvents,Residual Oil,Wax Oil,Slurry,Hydrogen,Propylene,Caustic Soda,Frozen Salt Containing Thermobody,Acid,Alkaline,Alkaline Solution,Liquid Gas, Water Asbestos Rubber Sealing Products China's asbestos resources are abundant. Asbestos can be loosened by mechanical or chemical treatment. Asbestos fibers that are fully loosened have higher tensile strength, larger surface area, good adsorption performance, and can not burn, and have good heat resistance. The highest safe use temperature is 500 ~ 550 °C, this temperature range can basically meet the needs of industrial workers, and asbestos cheap, its drawback is that asbestos dust pollution to the environment, the human body is harmful, we must pay attention to environmental protection.

Asbestos rubber seal products can be divided into the following three categories:

1 Gaskets—Plate and sheet seals used on pipe flanges and container flanges;

2 Gaskets - Molded, sealed products used on pumps, valves, kettles;

3 Packing - Rope and velvet seals used on pumps, valves, kettles.

Asbestos rubber sheet is made of asbestos, rubber, and compounding agent. It is used to seal the tube flange, high-pressure container flange and various contact surfaces.

Asbestos oil-resistant rubber sheet is made of asbestos, oil-resistant rubber and compounding agent as the main raw material, and the sealing material used for the pipe flange, high-pressure vessel flange and various contact surfaces made by roll pressing.

Reinforced asbestos rubber sheet is composed of asbestos rubber sheet and a layer of geese or galvanized steel mesh (or stainless steel wire mesh). Generally divided into oil-reinforced plates and high-pressure enhanced plates. The number of layers of the steel mesh is related to the thickness of the products. In general, for every 1 mm increase in the thickness of the product, a layer of steel wire mesh should be added. The steel wire mesh should be sandwiched between the corresponding bisection and trisection of the asbestos rubber to increase the tension. Strength, so that it can withstand high temperatures and high pressure. Thin gaskets should be used in places with high temperature and pressure. The shim can function as a metal shim, and it can also be said to function as a direct "flat and planar" seal, where the roughness and flatness of the seal surface should be high. Reinforced asbestos rubber sheet thickness generally does not exceed 3mm.

With the development of petroleum, chemical, aviation and national defense. High-temperature high-pressure and ultra-high-pressure equipment, management and the emergence of high-speed, small-size, high-power development machines, general asbestos rubber sheet can no longer meet the needs, should have high temperature, high pressure, oil resistance, non-flammable, good elasticity, can adapt to temperature Features such as large fluctuations in pressure, and should have a long service life and excellent sealing performance. Therefore, only the reinforced asbestos rubber sheet and the following asbestos steel sheet, wound gaskets, etc. can meet these requirements.