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Causes and treatment of valve leakage

2018-07-04


If the sealing part of the disc and seat of the safety valve leaks beyond the rated range, the medium will be lost and the sealing material will be damaged. - Generally, the sealing surface of the safety valve is mainly composed of metal materials, and it should be smooth and flat as much as possible. However, in the case of secondary extrusion of media with 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 be detected simply by visual observation and ear. The main reasons for valve leakage are as follows: (1) Dirt and sundries appear on the sealing surface, and the originally sealed plane is blocked and separated, so that there is a gap between the valve core and the valve seat This causes leakage of the valve. To solve this kind of problem, it is usually to clean the dirt and sundries on the sealing surface. When the boiler is temporarily out of service for maintenance, the escape weight test shall be carried out on the safety door first, and the overall maintenance shall be carried out once there is leakage. - The interval of the general running weight is 20 minutes after the complete cooling. (2) The sealing surface is damaged. There are many reasons, such as: First, the sealing materials are unqualified. After a safety valve has been used for many years, it is very easy to weaken the strength of the sealing surface due to continuous opening, running in, maintenance and other reasons, thus weakening the sealing ability. The recommended measure to solve this problem is to flatten the original sealing surface, and carry out secondary processing and welding according to the original drawings to enhance the hardness and strength of the surface. And pay attention to the damage on the surface, and do not be careless. The second is maintenance quality. Due to the poor maintenance level, the valve core and valve seat cannot reach a certain level in the grinding process. The solution is to repair the sealing surface as much as possible by grinding or even turning depending on the severity of the damage. Third, improper assembly or wrong part size. During the whole assembly work, the valve core and valve seat are not completely aligned, or there is a serious problem of light transmission on the joint surface, or it may be that the sealing position of the valve core and valve seat is too loose to really seal. The solution is to strictly check the length, thickness and distribution of the gap near the valve core, and ensure that the gap of each part can not lift the valve core, and properly reduce the width of the sealing surface according to the data on the drawing to seal.



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