Now many flanged gate valves are in use, because the correct installation method is not used, which leads to various failures of flanged gate valves, so when we install flanged gate valves, we must understand the relevant installation.
1. The flanged gate valve should be checked for leakage before opening to determine whether the valve has no leakage defects and whether the stuffing box has no leakage defects.
2. If the valve stem operation of the flanged gate valve cannot be done by hand, it can be replaced by a special F wrench. However, when the F wrench still cannot be opened, do not use the extended wrench to forcibly open and close it to avoid valve damage or even safety accidents.
3. When the flanged gate valve is used in the medium pressure gas pipeline, the condensed water needs to be removed before opening, and then the pipeline is preheated with steam, and the preheating pressure is maintained between 0.2 and 0.3MPA.
The purpose of this is to avoid damage to the seal caused by sudden changes in temperature and pressure, and the pressure can be adjusted to the required level after it is determined that the state is stable.
Now in the process of using the flanged gate valve, it will encounter many problems, so how should we solve these problems? What methods can be used to avoid these failures?
The main factors that affect the dead zone of the electric valve: friction, travel, valve shaft torsion, and the dead zone of the amplifier. The sensitivity of various control valves to friction is different.
For example, rotary valves are very sensitive to friction caused by high seat loads, so pay attention to this when using them. But for some seal styles, a high seat load is necessary to obtain the shutoff rating.
This kind of valve is very poorly designed, and it is easy to cause a large dead zone. The impact on the process deviation is obvious and decisive.
Wear: Wear of the electric valve is inevitable during normal use, but the wear of the lubricating layer is relatively fast, and the load caused by the pressure will also lead to the wear of the sealing layer, which are the main factors leading to the increase of friction.
Packing friction is the main source of friction in the control valve, and the friction caused by different packings is very different.
Different types of actuators also have a fundamental impact on friction, generally speaking, spring-film actuators are better than piston actuators.