If the disc and seat are leaking out of the rated range,then the medium will be lead to run off,and also the seal material will be damaged.In general,the seal of brass valves is mainly made of brass materials,and all produced to be smooth and flat, but when the seal went through in the stressful medium under the condition of secondary extrusion,it will be impossible to keep the seal no leaking.Therefore,in the rated stable stressful condition,the valve can be detected by visual observation and ear hearing when the medium is steam.There are two mainly reasons for valve leakage:
(1) There are dirt and debris appears on the sealing surface, and the original sealing surface is blocked and separated, resulting in a gap between the valve core and the seat, caused leakage of the valve.To solve this kind of problem,you should clean the dirt on the sealing surface.When the boiler is temporarily stopped and ready for maintenance,the safety door should be tested by running lead first. -- the interval of the lead is 20 minutes after the complete cooling.
(2) The damagement of sealing surface.There are many causes,firstly, the materials used for sealing are unqualified.While the valves used for many years,one side of the valve is vulnerable to the weakening of the strength of the sealing surface,due to the continuous on-off and on-off maintenance, that will lead to the weakening of the sealing capacity. The suggestion to solve this problem is to cut the original sealing surface flat and conduct secondary processing and welding,according to the original drawings to enhance the hardness and strength of the surface. And pay attention to the surface damage, do not be careless.
Second,it is maintenance quality.As a result of poor maintenance level,the valve core and seat in the grinding process can not reach a certainly level.The solution is to repair the sealing surface as much as possible by grinding,even turning depending on the severity of the damage.
Third,improper assembly or part size.In the whole assembly work,the valve core and valve seat not alignment,or the juction surface appeared serious light transmission problem,also the valve core and valve seat seal coule be too loose,became really hard to sealed.The solution is strictly check the length of the gap and the thickness distribution of valves core, and ensure that the clearance will not lift, the parts according to the data on the drawings to properly reduce the width of the sealing surface.