What should I pay attention to when using gaskets with flange connections?
Definition of gasket:
The gasket is made of paper, rubber sheet or copper sheet. It is a material placed between two planes to strengthen the seal. It is a sealing element arranged between static sealing surfaces to prevent fluid leakage. When the flange sealing surface is matched with the gasket, the following points should be noted:
1. Thread of flange
Thread is the main direction of flange surface roughness, such as: multi-direction, recording spiral, serration and other surface finish patterns should be as close as possible to the center line of the gasket to be consistent, such as round flanges. The surface texture should be processed into concentric circles or recording spirals to avoid straight lines passing through the flange surface. If there is a straight line across the sealing surface, it will become a direct leakage path. If the gasket needs to be used in conjunction with the flange, then you need to pay attention to this point.
2. Waviness of flange
The waviness is the deviation from the overall flatness. Under normal circumstances, there is no need to consider the waviness problem, but there are two situations that require special attention, because excessive waviness is also a difficult problem to solve.
3. Roughness of flange
Roughness refers to the average value of unevenness calculated from the center of the flange surface, in units of tenths of inches (or meters). For serrated flange surfaces, the typical roughness is 125-500 microinches, while for non-serrated flange surfaces, the roughness is 125-250 microinches. For flanges that are too rough, it is usually impossible to seal the gasket, so you can only choose the softest possible gasket; on the other hand, it is difficult to seal the surface of the flange with a high degree of polishing. This kind of flange should also be avoided because of the sealing The surface needs to have enough “bite marks” to provide enough friction to prevent the gasket from being blown out or extruded or excessive creep.
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