The melt pump extrusion gasket selection principle

　　The melt pump extrusion gasket selection principle

　　The melt pump extrusion gasket selection principle is that for less demanding situations, empirically selected, and then the differences timely replacement. But for those demanding applications, such as explosive, toxic and combustible gases and highly corrosive liquid equipment, reaction tank and the pipeline system should be based on resistance and binding work pressure, temperature, sealing medium sealing surface The form of the selection. In general, low pressure at room temperature, the selection of non-metallic gaskets soft honey; when the pressure high-temperature, use a combination of metal and non-metallic gaskets or metal gasket; temperature, pressure greater volatility, the selection of good flexibility or self-tight seal; at low temperature, corrosive media or vacuum conditions, should be considered a special performance of the gasket. It should be noted that the impact of the case on the flange gasket choice.

　　Flange effects. Flange different requirements of the gasket used is also different. Smooth face flange is generally used for low pressure, with soft thin gasket; at high pressure, if the strength of the flange is sufficient, you can also use a smooth face flange, but it should be with a thick soft pad, or a reinforcing band ring or gasket wound reinforcement ring. In this case, the metal gasket does not apply, since then the required clamping force is too large, resulting in large deformation bolt, the flange seal is not easy. If you use a metal gasket, it should be smooth surface narrow to reduce the contact area with the gasket. Thus, in the case of the same bolt tension, stress narrow pressing the smooth surface will increase after the reduction.

　　Flange surface roughness effects. Surface roughness of the flange sealing effect is large, especially when using non-soft gaskets, seals the surface roughness value is the main cause of large leaks. For example, turning on the flange surface knife pattern is spiral, the use of metal gaskets, if the roughness is larger, the gasket can not be blocked this knife pattern of spiral grooves formed, under pressure, the media will along this trench leaked. Soft gasket on the flange surface finish degree requirements are much lower, which is due, it is easily deformed, can block the process knife pattern, thereby preventing leakage. For soft gaskets, flanges too slick detriment, because this time the leak occurred interface resistance becomes smaller. Therefore, various gaskets, flange surface roughness required is not the same.