Regarding the selection of new sand making machine seals, in the case of lower requirements, they can be selected based on experience, and they can be replaced if they are not in the market. However, for those demanding applications, such as explosive, highly toxic, combustible gas and corrosive liquid equipment, reaction tanks and piping systems, etc., the working pressure, working temperature, corrosiveness of the sealing medium and the combined sealing surface to make sure. Generally, when the temperature is low at normal temperature, please use a non-metal sander soft gasket; at medium pressure and high temperature, use a metal and non-metal combined washer or metal washer; when the temperature and pressure fluctuate greatly, choose elasticity. Good or self-tight gaskets; gaskets with special properties should be considered under low temperature, corrosive media or vacuum conditions. What needs to be explained here is the influence of flange conditions on gasket selection. The influence of the flange form of the sand maker. Different flange shapes require different gaskets. Smooth surface flanges are usually only used for low pressure and have soft, thin gaskets; under high pressure, if the flange is strong enough, a smooth flange can be used, but using thick cushions or reinforcing rings in the pipeline, Or strengthen the wrap around the gasket. In this case, a metal washer is also inappropriate, because the pressure required at this time is too large, resulting in large deformation of the bolt, making the flange difficult to seal. If a metal washer is to be used, reduce the smooth surface to reduce the contact area with the washer. Therefore, with the same bolt tension, the compressive stress of the narrowed smooth surface increases. The influence of the surface roughness of the new sand making machine flange. The surface roughness of the flange has a great influence on the sealing effect, especially when a non-soft gasket is used, a large sealing surface roughness is one of the main causes of leakage. For example, the blades that rotate the surface of the flange are helical. When using a metal washer for a new type of sand maker, if the roughness value is large, the washer cannot block the spiral groove formed by the blade. Under pressure, the medium will be stressed. Leaks along this groove. Soft washers require a smoother flange surface because it deforms easily and hinders tooling to prevent leaks. For soft gaskets, the flange surface is too smooth and unfavorable because the interface leakage resistance is reduced. Therefore, different flanges require different flange surface roughness.