Regulating valve in the high, low temperature valve does not work the normal solution (5 methods)
1) uniform line swelling decreased two-seat valve leakage method
Two-seat valve in the normal temperature test, the leakage is not too large. However, an input high temperature leakage volume soared. This is because the seat is fixed on the valve seat sealing surface of linear expansion linear and valve sealing surface is not a double expansion caused by a DN50. If the valve seat, valve core is made of stainless steel, valve for carbon steel, used in F at room temperature 70 degrees in the sealing surface of the valve seat and valve, expansion of 0.06mm sealing surface line, an increase of leakage is more than 10 times. The solution:
The selection of the valve body and the valve core are made of the same material, the stainless steel valve. But stainless steel valve than carbon steel valve high price by more than 3 times. From the perspective of economy should be considered;
The selection of the sleeve valve replaced, due to the sealing surface of the sleeve, the sleeve and the valve plug is the same material.
2) the valve seat sealing welding method
When the temperature up to 750 ° F, the seat of threaded connection caused by leakage in the surface and the thread seal is connected with the valve, which can be threaded erosion, dangerous seat falling, encounter this kind of failure, should think of seal welding of the valve seat, to prevent loosening and shedding.
3) lining welding method
As on the spool, the valve plug, valve stem guide bushing, the vast majority of occasions are statically matched. Regulating valve in the indoor combination, work in high and low temperature, not a cause with diameter minor variations of the linear expansion, bushing with occasionally encountered interference is minimal, or bushing and valve due to a foreign body stuck in the spool movement under the pull, Bush will fall off. This fault is not much, but have occurred. In this regard, the bushing welding, to ensure that Bush never falling.
4) increase the guide bushing gap method
At high temperature, when the diameter of bushing with a diameter expansion is not a line, and the shaft is larger than the expansion bushing inner hole, shaft movement or rotation will produce card jumps, such as high temperature butterfly valve. If the actual operating temperature when the valve and the valve operating temperature requirements, may be the factory quality problems. To solve the problem, natural is to increase the gap clearance. A simple solution is to put the guiding position of shaft diameter small car 0.2 ~ 0.5mm, and should try to improve the smoothness.
5) packed back-to-back mounting method
The deep freeze temperature valve, due to pipeline when cooled to form a vacuum, if from the padding to the valve body can be vented, double packing layer or the filling part is installed back to back, to stop the atmosphere through the stem seal leak.
