If there is leakage beyond the rated range in the sealing part of the disc and seat of the safety valve, it will lead to the loss of medium and damage the sealing material. In general, the sealing surface of the safety valve is mainly composed of metal materials, and try to be smooth and flat. However, in the case of secondary extrusion of the medium with pressure, it is impossible to require complete sealing without leakage. Therefore, in the rated pressure environment, the safety valve with steam as the medium can be detected only by visual observation and ear hearing. The main reasons for valve leakage are as follows:



(1) There are dirt and debris on the sealing surface, and the original sealing plane is blocked and separated, so that there is a gap between the valve core and the valve seat, leading to the leakage of the valve. To solve this kind of problem, it is usually to clean the dirt on the sealing surface. When the boiler is temporarily out of service for maintenance, the safety door should be tested first, and once there is leakage, it should be overhauled as a whole. Generally, the interval between running mounds is 20 minutes after complete cooling.



(2) The sealing surface is damaged. There are many reasons, such as: first, the sealing material is unqualified. After many years of use, it is easy to weaken the strength of the sealing surface due to continuous opening and running in maintenance and other reasons, thus 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, so as to enhance the hardness and strength of the surface. And pay attention to the surface damage, must not be careless.



Second, maintenance quality. Due to the poor level of maintenance, the grinding process of valve core and valve seat can not reach a certain level. The solution is depending on the severity of damage to use grinding or even turning and other means to repair the sealing surface as much as possible.



Third, improper assembly or wrong size of parts. In the whole assembly work, the valve core and the valve seat are not completely aligned, or there is a serious light transmission problem on the joint surface, or the sealing place of the valve core and the valve seat is too loose to really seal. The solution is to strictly check the length, thickness and distribution of the gap beside the valve core, and ensure that the valve core can not be lifted by the gap of each part. According to the data on the drawing, the width of the sealing surface should be appropriately reduced to seal.