The basic principle of self-tightening sealing bonnet
The necessary condition for forced sealing is that under the action of the medium and the operating force, the sealing surface can still maintain a certain compressive force. It should be emphasized that: in forced sealing, the medium pressure always tends to reduce the preloaded seal compared with the pressure to reduce the sealing performance. The typical structures of forced sealing are flat gasket, wound gasket and toothed gasket. Usually used for low pressure, medium pressure and small and medium bore valves.
In the self-tightening seal, the specific pressure of the working seal on the sealing surface is composed of two parts: one is the specific pressure of the pre-tightening seal, and the other is the specific pressure formed by the medium pressure. It should be emphasized that: in self-tightening seals, the medium pressure always tends to increase the specific pressure of the pre-tightening seal and increase the sealing performance. The higher the medium pressure, the greater the specific pressure of the working seal. According to this feature, self-tightening seals are often used in high-temperature, high-pressure large-diameter control valves as a high-pressure sealing technology.