Causes of valve leakage and treatment methods

If there is leakage beyond the rated range between the valve disc and the valve seat of the safety valve, it will lead to the loss of the medium, which will destroy the sealing material. - Under normal circumstances, the sealing surface of the safety valve is mainly composed of metal materials, and it is as smooth and flat as possible, but in the case of secondary extrusion of the medium with pressure, it is impossible to require complete sealing and no leakage. of. Therefore, under the rated pressure environment, the safety valve with steam as the medium can be detected by visual observation and ear listening. The main reasons for valve leakage are as follows:

(1) Dirt and debris appear 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, resulting in leakage of the valve. To solve this type of problem, it is usually to clean up the dirt and debris on the sealing surface. When the boiler is temporarily out of service for maintenance, the safety door should be tested for running weights first, and if there is leakage, it should be overhauled as a whole. - The general running interval is 20 minutes after complete cooling.

(2) Damage to the sealing surface. There are many reasons, such as:

First, the material used for sealing is unqualified. On the one hand, after many years of use of the safety valve, the strength of the sealing surface is easily weakened due to the continuous opening and closing, running-in maintenance and other reasons, and thus the sealing ability is weakened. The suggested measure to solve this problem is to flatten the original sealing surface, and perform secondary processing and welding according to the original drawing to enhance the hardness and strength of the surface. And pay attention to the damage on the surface, be sure not to be sloppy.

The second is the quality of maintenance. Due to the poor level of maintenance, the grinding process of the valve core and valve seat cannot reach a certain level. 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 third is improper assembly or the wrong size of parts. During 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 part of the valve core and the valve seat is too loose, and it is difficult to achieve a real seal. The solution is to strictly check the length, thickness and distribution of the gaps next to the valve core, and ensure that the gaps in each part cannot lift the valve core, and appropriately reduce the width of the sealing surface to seal according to the data on the drawing.