Causes of Valve Leakage and Its Preventive Measures (Part Three)

2. Main measures to prevent leakage
2.1 Reasonable material selection to reduce the occurrence of corrosion
As the carrier of the medium, the corrosivity of the medium has a critical impact on the leakage of the valve. The corrosivity will cause the corrosion of chemical and physical properties of different materials. No matter what kind of corrosion, the valve will be damaged, resulting in leakage. Therefore, in the process of using the valve, we should first do a good job of anticorrosion, and choose different valve materials according to the different media carried, so as to increase its corrosion resistance. The corrosion effect of medium on valves is directly related to the concentration, temperature and pressure of medium. The increase of medium temperature, concentration and pressure will accelerate the corrosion. Because the corrosivity produced by various media is different and has very complex characteristics, in the actual selection process of valve materials, it is necessary to analyze the corrosion factors produced according to different situations, in order to select suitable materials.

2.2 Appropriate opening and closing force to prevent the damage of sealing surface
In the actual pipeline system, the manual valve at normal temperature and pressure is widely used. The handwheel and handle of this valve are designed according to ordinary manpower, so it can only be operated by hand, not by wrench. Because if the wrench is used for operation, the thread of the valve stem will be damaged, which will lead to the failure of opening and closing and cause accidents. At the same time, during operation, we should also pay attention to the use of strength, and do not use too much force, so as not to damage the handwheel or handle. In addition, when the handwheel or handle is damaged or lost, it should be fully equipped immediately and resolutely put an end to the use of spanners.

2.3 Open and close the valve correctly to prevent the valve from being damaged.
For high-temperature and high-pressure valves, they should be heated in advance before opening, and the condensed water should be removed. When opening, try to be slow to avoid water hammer. When the valve is fully opened, the handwheel should be reversed a little, so that the threads are tight to avoid looseness and damage. For open stem valves, remember the position of the valve stem when fully open and fully closed, and avoid hitting the top dead center when fully open. If the disc falls off or sundries are embedded between the valve core seals, the valve stem position will move when it is fully closed. When the valve is just started, there are certain sundries in the pipeline, so the valve can be opened slightly,. The impurities can be washed away by using the high-speed flow of medium. Then closed and opened again, this is repeated many times to wash away the sundries. For normally open valves, sundries may stick on the sealing surface, which should be washed clean repeatedly before closing. When the medium cools after the valve is closed, the valve plate will shrink, so the operator should close it again at an appropriate time, leaving no gap on the sealing surface.