如何选择合适的垫圈

垫圈的选择原理是，对于更少的苛刻场合，可以根据经验选择，并且在不适合时更换。但对于那些严格的要求，如：爆炸性，高度毒性可燃气体和高度腐蚀性的液体设备，反应箱和宽松的管道系统等，根据工作压力，工作温度，密封介质的腐蚀性和组合密封表面选择。

一般而言，在常温和低压下选择非金属软垫圈;在中压和高温下选择金属和非金属复合垫圈或金属垫圈;当温度和压力大大波动时，使用弹性或自紧固型垫圈;在低温下，腐蚀性介质或真空条件下，应考虑具有特殊特性的垫圈。这里需要解释的是法兰条件对垫圈选择的影响。

　　 Influence of flange form: Different flange forms require different gaskets. Smooth flanges are generally only used for low pressure, thin gaskets with soft configuration; under high pressure, if the flange is strong enough, smooth flanges can also be used, but thick soft pads or reinforced with tape should be used Wrapped gasket for ring or outer reinforcement ring. In this case, the metal gasket is not used, because the pressing force required at this time is too large, resulting in large deformation of the bolt, making the flange difficult to seal. If a metal gasket is used, the smooth surface should be reduced to reduce the contact area with the gasket. In this way, when the spiral tension is the same, the compression stress of the narrow smooth surface after shrinkage will increase.

　　 Influence of flange surface roughness: Flange surface roughness has a great influence on the sealing effect, especially when non-soft gaskets are used, a large sealing surface roughness value is one of the main causes of leakage. For example: the cutting pattern of the turning flange surface is a spiral line. When using a metal gasket, if the roughness value is large, the gasket cannot block the spiral groove formed by the cutting pattern. Under the pressure, the medium will be Leak along this groove. The soft gasket requires a much lower level of smoothness on the flange surface. This is because it is easily deformed and can block the processing knife lines, thereby preventing leakage. For soft gaskets, the flange surface is too smooth but unfavorable, because the resistance to interface leakage becomes smaller at this time. Therefore, the required roughness of the flange surface is different for different gaskets.