In the process of daily inspection, sealed pressure devices such as boilers, pressure vessels, and pressure pipelines can not be separated from the silicone rubber gaskets. However, because most people lack professional knowledge in the selection and application scope of silicone rubber gaskets, they only choose by experience, which is bound to produce some misunderstandings. So the running, taking, dripping, and leakage phenomenon is common, causing a lot of waste to the unit, and even due to the failure of the silicone gasket caused by serious accidents. These situations are mainly due to the selection and assembly of the silicone gasket. Given the above situations, it is necessary to make a specific introduction to the selection of silicone rubber gasket.
The role of a silicone gasket is to prevent the leakage of the sealed medium, and the form of leakage can be divided into interface leakage and penetration leakage. The cause of interface leakage is usually due to the relaxation of the pressing force between the sealing surface, aging, deformation, corrosion, wear or burn of the sealing surface, and mechanical vibration under working conditions. The infiltration leakage is related to the material type of silicone gasket, the manufacturing method, the nature of the sealed medium, and the working pressure, temperature, and other factors.
Theoretically speaking, even if the silicone gasket is used, it is impossible to achieve complete contact between the sealing surface, so that there is no microscopic channel or gap. Although these channels are extremely small, the molecular volume of the fluid medium is still large enough, so it is impossible to prevent the fluid completely at the edge of the sealing surface. There is always a part of the fluid entering the sealed contact between the surface, and there is a complex hydrodynamic and thermodynamic process. It is generally believed that after the fluid enters the extremely small and irregular gaps between the sealing surface, it will generate resistance loss in the flow process to consume its energy. At the same time, the static boundary layer will be generated on the wall of these gaps, which will make the small channel become more narrow or even completely blocked so that the fluid entering the sealing surface can not continue to flow, to realize the sealing.