In the automatic control of modern chemical plants, regulating valves play a very important role. The production of these plants depends on the correct distribution and control of flowing media. These controls, whether it is energy exchange, pressure reduction, or simple container feeding, require certain ultimate control components to be completed.
Regulating valves belong to the control valve series, mainly used to regulate the pressure, flow rate, temperature and other parameters of the medium, and are the ultimate control components in the process loop. How to solve the problem of electric control valve leakage
1) Add sealing grease method
For electric control valves that do not use sealing grease, adding sealing grease can be considered to improve the sealing performance of the valve stem.
2) Add filling method
To improve the sealing performance of the packing on the valve stem, the method of adding packing can be adopted. Usually, double-layer or multi-layer mixed fillers are used, and simply increasing the quantity, such as increasing 3 pieces to 5 pieces, does not have a significant effect.
3) Replacing graphite packing method
The widely used PTFE packing has a working temperature range of -20 to 200 ℃. When the temperature changes significantly between the upper and lower limits, its sealing performance decreases significantly, aging quickly, and its lifespan is short. Flexible graphite fillers can overcome these drawbacks and have a long service life. Therefore, some factories have completely replaced PTFE packing with graphite packing, and even newly purchased regulating valves have replaced PTFE packing with graphite packing before use. However, the use of graphite fillers has a large backlash, and some may even experience crawling at the beginning, which must be considered.
4) Change the flow direction and place P2 at the valve stem end
When Δ P is large and P1 is also large, sealing P1 is obviously more difficult than sealing P2 Therefore, the method of changing the flow direction can be adopted, changing P1 at the valve stem end to P2 at the valve stem end, which is more effective for valves with high pressure and large pressure difference For bellows valves, P2 sealing should usually be considered.
5) Using lens gasket sealing method
For the sealing of the upper and lower covers, the sealing between the valve seat and the upper and lower valve bodies If it is a flat seal, the sealing performance is poor under high temperature and high pressure, causing leakage. Lens gaskets can be used for sealing, which can achieve satisfactory results.
6) Replace the sealing gasket
Until now, most sealing gaskets still use asbestos board, which has poor sealing performance and short lifespan at high temperatures, causing leakage. In this situation, wrapped gaskets, "O" rings, etc. can be used instead, which are now adopted by many factories.

Shanghai Mingjing Anti corrosion Valve Manufacturing Co., Ltd

Technical Department