Causes And Treatment Methods Of Cast Steel Stop Valve Leakage

If the sealing area between the valve disc and the valve seat of the Cast Steel Globe Valve exceeds the rated range, the medium will be lost, which will damage the sealing material. Generally, the sealing surface of the safety valve is mainly composed of metal materials, and it is smooth and flat as much as possible. However, it is impossible to require complete sealing without leakage under the secondary extrusion of the pressurized medium. Therefore, under the rated pressure environment, the safety valve with steam as the medium can be detected simply by naked eye 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 a gap appears between the valve core and the valve seat, causing valve leakage. To solve this kind of problem, the dirt and debris on the sealing surface are usually cleaned. When the boiler is temporarily shut down for maintenance, the safety door should be tested first. If there is leakage, it should be inspected as a whole. The interval between running is generally 20 minutes after complete cooling.

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

First, the sealing material is unqualified. After years of use, the strength of the sealing surface of a safety valve is easily weakened due to continuous opening and closing, running-in and maintenance, which in turn weakens the sealing ability. The recommended measure to solve this problem is to flatten the original sealing surface and perform secondary processing and welding according to the original drawings to enhance the hardness and strength of the surface. In addition, pay attention to the damage on the surface and do not be careless.

Second, 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.

Third, improper assembly or incorrect part size. During the entire assembly work, the valve core and valve seat are not fully aligned, or there is a serious light transmission problem on the joint surface. It may also be that the seal between the valve core and valve seat is too loose and difficult to truly 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 between the parts cannot lift the valve core, and appropriately reduce the width of the sealing surface according to the data on the drawing to perform sealing.