The valve disc and seat part of the seal if there is leakage beyond the rated range, then it will lead to the loss of media, and then destroy the sealing material. Generally speaking, the sealing surface of the relief valve is mainly made of metal material, and it is smooth and smooth as far as possible. However, in the case of secondary extrusion with pressure medium, it is impossible to require complete sealing without leakage. Therefore, in the rated pressure environment, with steam as the medium of the safety valve can simply rely on the naked eye observation and ear to detect. The main reasons for valve leakage are the following two points:
(1) dirt and impurities appear on the sealing surface, and the original sealing plane is blocked and separated, resulting in a gap between the valve core and the valve seat, resulting in leakage of the valve. To solve this problem, dirt is usually on the sealing surface. When the boiler is temporarily shut down for maintenance, the safety door should be tested first, and the whole maintenance should be carried out once leakage occurs. The interval between running weights is 20 minutes after complete cooling.
(2) damage of sealing surface. There are many reasons, such as: first, the sealing material is not qualified; one side of the safety valve in use for many years, it is very easy to cause the strength of the sealing surface is weakened due to continuous switch running-in overhaul and other reasons, and then lead to the sealing capacity is weakened. The proposed solution to this problem is to flatten the original seal surface and weld it by secondary processing according to the original drawings to enhance the surface hardness and strength. And pay attention to surface damage, do not be careless.
The two is the quality of maintenance. Due to poor level of maintenance, the spool and valve seat can not reach a certain level in the grinding process. The solution is to use grinding or even turning to repair the sealing surface as much as possible, depending on the severity of the damage.
The three is improper assembly or incorrect size of parts. In the whole assembly work, the spool and the valve seat are not completely aligned, or there is a serious problem of light transmission on the joint surface, or it may be too loose to seal the spool and the valve seat seals, it is difficult to really seal. The solution is to strictly check the size and distribution of the gap near the core, and to ensure that the gap between the various parts of the valve core can not be lifted, according to the drawings on the data to reduce the width of the sealing surface to seal properly.