Seal structure and leakage
The gasket is a kind of roller fitting for the roller seal, which has excellent protection against dust intrusion into the roller.
Seal sealing mechanism
The function of the gasket is caused by the internal medium blocking effect formed by the contact pressure of the sealing material with respect to the joint surface and the elastic restoring force for the fastening external force.
Classification and structure of gaskets
Seals are divided into non-metallic seals, non-metallic and metal combination seals and metal seals. The materials are commonly found in rubber, leather, asbestos, cork, PTFE, tinplate, steel, aluminum, copper and Stainless steel, etc.
Hebei Innovation Sealing Material Co., Ltd. (graphite packing, graphite packing, PTFE packing, high water based packing, aramid packing, carbon fiber packing, ceramic fiber packing, fiberglass packing, Gore packing, Butter packing, ramie packing, butter packing, cotton packing, coarse hemp root, etc.)
Third, the choice of gasket
The principle of selection of the gasket: according to the working pressure, working temperature, corrosiveness of the sealing medium and the form of the combined sealing surface. Generally speaking, when the temperature is low and normal, the non-metallic soft honey seal is used; when the medium pressure is high temperature, the metal and non-metal combination seal or metal seal is used; when the temperature and pressure have large fluctuations, the elasticity is good. Or self-tightening gaskets; gaskets with special properties should be considered in low temperature, corrosive media or vacuum conditions. Effect of the flange form: The flanges are different in form and the required gaskets are different. Smooth surface flanges are generally only used for low pressure, with soft thin gaskets; under high pressure, if the strength of the flange is sufficient, smooth flanges can also be used, but thick soft mats should be used, or in-band reinforcement A wound gasket of a ring or a reinforcing ring. In this case, the metal gasket is also not suitable, because the pressing force required at this time is too large, resulting in a large deformation of the bolt, making the flange difficult to seal. If a metal gasket is to be used, the smooth surface should be reduced to reduce the contact area with the gasket. Thus, in the case where the bolt tension is the same, the pressing stress of the narrowed smooth surface is increased.
Seal leakage
There are four types of leakage phenomena in general gaskets: interface leakage, seepage leakage, diffusion leakage, and damage leakage.
Interface leakage: The interface will leak at the sealing interface due to insufficient gasket pressing, improper flange joint surface finish, and flange deformation. For the interface leakage, it can be prevented by clamping the cushion material in the flange surface.
Hebei Innovative Sealing Material Co., Ltd. is mainly engaged in sealing gasket products (metal wound gasket, basic metal wound gasket, metal wound gasket with inner ring, metal wound gasket with outer ring, stainless steel spiral gasket, graphite composite gasket Sheet, octagonal gasket, toothed gasket, copper gasket, PTFE gasket, asbestos gasket, etc.)
Penetration leakage: Since the material of soft materials is mostly fiber, it is easy to be immersed in the medium, especially the pressure. Due to the capillary phenomenon, the medium will penetrate to the low pressure side to form an infiltration.
Diffusion leakage: Under the push of the concentration difference, the medium is leaked by the substance transported by the seal gap or the capillary of the sealing material. Diffusion is the result of molecular motion and is not unidirectional. Pay special attention to both leakage and diffusion when the sealing pressure difference is very small or vacuum, or when sealing osmotic substances such as nitrogen and hydrogen, as well as highly toxic and radioactive substances.
Destruction of leakage: working conditions in the sealing part are relatively harsh, thermal deformation is large, often subject to vibration, impact, improper installation, excessive tightening force, repeated use, compression deformation, internal stress concentration, damage beyond fatigue strength, material aging Deterioration, etc. will cause damage to the leak. This kind of leakage has the greatest impact and the harm is also great. It is necessary to strengthen prevention.
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