If the Double Acting Pneumatic Rotary Actuator safety valve's disc and seat seals leak beyond the rated range, it will cause medium loss and further damage the sealing material. Generally speaking, the sealing surface of the safety valve is mainly composed of metal materials, which should be as smooth and flat as possible. However, if the medium is squeezed out under pressure, it is impossible to require complete sealing without leakage. Therefore, under the rated pressure environment, the safety valve with steam as the medium can only be detected by visual observation and ears. The main reasons for valve leakage are as follows:
(1) Dirt and debris appear on the sealing surface, and the original sealing surface is blocked and separated, resulting in a gap between the valve core and the valve seat, resulting in valve leakage. In order to solve this kind of problem, it is usually to clean the dirt and debris on the sealing surface. When the boiler is temporarily shut down for inspection and maintenance, the safety valve should be subjected to a weight test first. In case of leakage, overall maintenance should be carried out. After cooling completely, run the weights 20 minutes apart.
(2) The sealing surface is damaged. There are many reasons, such as: the sealing material is unqualified. After many years of use, the strength of the sealing surface is easily weakened due to continuous opening and closing, running-in and maintenance, thereby weakening the sealing ability. The suggested measure to solve this problem is to flatten the original sealing surface, and carry out secondary processing and welding according to the original drawing to improve the hardness and strength of the surface. And pay attention to surface damage, don't be careless.
Maintain quality. Due to the poor maintenance level, the grinding process of the valve core and valve seat cannot reach a certain level. The solution is to restore as much of the sealing surface as possible, using grinding or even turning, depending on the severity of the damage. Improper assembly or wrong size parts. During the whole assembly process, the valve core and the valve seat are not completely aligned, or the joint surface has serious light transmission problems, or the seal between the valve core and the valve seat may be too loose to be truly sealed. The solution is to strictly check the length, thickness and distribution of the gap next to the spool, and ensure that the spool cannot be lifted through the gap of each part. The width of the sealing surface should be appropriately reduced according to the data on the drawing for sealing.
