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Application And Selection Of Metallic Seal Gaskets In Gear Pumps
- Jun 15, 2018 -

The principle of selection of gear pump seals is that they can be replaced when they are not suitable for occasions with low requirements. However, for those rigorous occasions, such as explosives, highly toxic and flammable gases, and highly corrosive liquid equipment, reaction tanks and conveying pipe systems, etc., they should be based on working pressure, working temperature, corrosivity of the sealing medium, and joint sealing surfaces. Form to choose. In general, non-metallic soft honey seals are used at normal temperature and low pressure; when metal pressure is high temperature, metal and non-metal combination seals or metal seals are used; when the temperature and pressure have large fluctuations, the elasticity is good. Or self-tightening seals; seals with special properties should be considered at low temperatures, corrosive media or vacuum conditions. What needs to be explained here is the effect of flange conditions on the gasket selection.

Effect of the flange form: Different flange types require different gaskets. Smooth surface flanges are generally used only for low pressure, with soft thin gaskets; under high pressure, if the flange is strong enough, smooth flanges can also be used, but thick soft pads should be used, or reinforced with tape. Ring or reinforcement ring winding seal. The metallic seal gasket is also not suitable because the pressing force required at this time is too large, resulting in a large deformation of the bolt and making the flange less sealable. If a metallic seal gasket is to be used, the smooth surface should be reduced so that the contact area with the gasket is reduced. In this way, under the same tension of the bolt, the compressive stress of the reduced narrow smooth surface increases.

The influence of the flange surface roughness: The flange surface roughness has a great influence on the sealing effect, especially when non-soft gaskets are used, the high degree of roughness of the sealing surface is one of the main causes of leakage. For example, when turning a flange surface, the knife pattern is a spiral. When a metallic seal gasket is used, if the roughness value is large, the gasket cannot block the spiral groove formed by the knife pattern. Under pressure, the medium will be Follow this groove and leak it out. Soft gaskets require much less cleanliness of the flange surface because it is easily deformed and can block the cutting pattern and prevent leakage. For a soft gasket, the flange surface is too smooth and unfavorable because the interface leakage resistance becomes smaller at this time. Therefore, different gaskets require different flange surface roughness.