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SBX seal gasket selection principle
- Jun 15, 2018 -

The principle of selection of gaskets is: For applications where the requirements are not high, they can be selected empirically and replaced when inappropriate. It should be selected according to the working pressure, working temperature, the corrosivity of the SBX seal gasketing medium and the form of the combined SBX seal gasketing surface.

In general, non-metallic soft SBX seal gaskets are used at normal temperature and low pressure; non-metal and metal composite SBX seal gaskets or metal SBX seal gaskets are used when medium pressure is high temperature; when the temperature and pressure have large fluctuations, the elasticity is good or Tight gaskets; special properties of gaskets should be considered at low temperatures, corrosive media, or vacuum conditions. The special need to explain here is the effect of the flange condition on the gasket selection.

1, the influence of the flange form

Different flanges require different gaskets. Smooth surface flanges are generally only used 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. Wrap around ring or outer reinforcement 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 and making the flange less SBX seal gasketable. If a metal 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.

2. Effect of flange surface roughness

Flange surface roughness has a great influence on the SBX seal gasketing effect, especially when using non-soft gaskets, SBX seal gasketing surface roughness is one of the main causes of leakage.

3, the hardness of the flange and gasket

The purpose of the use of gaskets is to make the gasket elastic or plastic deformation to fill the small surface of the flange surface to prevent leakage. Therefore, the hardness of the gasket material should be lower than the hardness of the flange material. The larger the difference between the two, the easier it is to achieve SBX seal gasketing. When using metal gaskets in gaskets, in order to ensure SBX seal gasketing, soft materials should be used as much as possible so that the hardness of metal gaskets is 40 HB or more lower than the flange hardness.