Release time：2023.01.20
Source: This website
Sealing gasket types have industrial rubber plate, metal winding pad, polytetrafluon, oval pad, metal cover pad, metal flat pad, today we will introduce these several sealing gaskets in detail.
First, industrial rubber plate
Rubber sheet as flange gasket, mostly used for pipeline or often removed manhole, hand hole, pressure does not exceed 1.568MPa. Because in all kinds of gaskets, rubber gaskets are the softest, good fitting performance, and can play a sealing effect under small preloading force. Because of this, when under internal pressure, due to the thickness of the gasket or low hardness and easy to be extruded. Rubber sheet used in benzene, ketone, ether and other organic solvents, easy to appear swelling, weight gain, softening, sticky phenomenon, leading to seal failure. General swelling degree more than 30% can not be used.
In the case of low pressure and vacuum, the rubber pad is more suitable. The rubber material has good density and low breathability. For example, fluorine rubber, the most suitable for vacuum container sealing gasket, vacuum up to 1.3×10-7Pa. When the rubber pad is used in the vacuum degree range of 10-1~10-7 PA, it needs to be baked and pumped.
Two, metal winding pad
Metal winding pad cleverly uses the heat resistance, resilience and strength of metal and the softness of non-metallic materials, so the sealing performance is better, and the stainless steel tape winding flexible graphite pad performance is the best. The preload pressure is smaller than that of asbestos winding pad, and there is no asbestos fiber capillary leakage.
Sealing gasket
Three, polytetrafluoroethylene
Ptfe friction coefficient is small, the gasket is easy to slip outward when pre-tightening, so it is best to use concave and convex flange surface. When the plane flange is used, the outer diameter of the gasket can be contacted with the bolt to prevent the gasket from sliding. Because the glass lining equipment is sintered after spraying a layer of porcelain glaze on the metal surface, the glaze layer is very brittle, coupled with uneven spraying and glaze layer flow, the surface flatness of the flange is poor. The metal composite gasket is easy to damage the glaze layer, so it is recommended to use the core material made of asbestos plate and rubber polytetrafluoroethylene cushion. This kind of packing is easy to fit with flange surface and corrosion resistant, and the use effect is good.
Four, metal cover pad
The advantages of metal cladding are high strength, unbreakable, firm and strong, but the resilience is limited, and the flange surface is required to be flat and the fastening force is very high to achieve good results. According to different materials can be combined into 201, 304, 316 stainless steel coated graphite (temperature resistance 650 degrees) coated pad, asbestos coated pad, ceramic fiber coated gasket and other forms.
Material: Q235A, stainless steel, copper, aluminum, etc
Filling material: flexible graphite, asbestos, asbestos free, ceramic fiber (10%), etc.
Purpose: Suitable for sealing flange of pressure vessel with large diameter. All kinds of medium machine pump, pipe valve, pipe and all kinds of equipment flange seal.
Five, metal flat pad
Generally used for medium and high pressure valves, pipes and small diameter equipment flanges. The use pressure is different according to the temperature, the former is 1.568~31.36MPa, the latter is 1.568~3.92MPa. Gasket material is selected according to medium and temperature.
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