Correct operation method of the valve: for the valve, not only the installation and maintenance, but also the operation.
1、 Opening and closing of manual valve:
1. The manual valve is a more widely used valve. Its handwheel or handle is designed according to ordinary manpower, taking into account the strength of the sealing surface and the necessary closing force. Therefore, do not use a long lever or a long wrench to move. Some people are used to using the spanner, so they should be careful not to use too much force, otherwise the sealing surface may be damaged, or the handwheel and handle may be broken.
2. When opening and closing the valve, the force shall be stable and shall not be impacted. Some parts of high pressure valves with impact opening and closing have considered that the impact force cannot be equal to that of ordinary valves.
3. For steam valve, it shall be heated in advance before opening, and condensate shall be discharged. When opening, it shall be slow as possible to avoid water hammer.
4. When the valve is fully opened, the handwheel should be turned back a little to make the threads tight to avoid looseness and damage. For rising stem valves, remember the valve stem position when fully open and fully closed to avoid hitting the top dead center when fully open. It is convenient to check whether it is normal when it is fully closed. If the valve stem falls off, or large debris is embedded between the valve core seals, the valve stem position will change when it is fully closed.
5. When the pipeline is used for the first time, there is a lot of dirt inside. You can slightly open the valve, use the high speed flow of the medium to flush it away, then close it gently (do not close quickly or violently to prevent the sealing surface from being pinched by residual impurities), and open it again. Repeat this for many times to clean the dirt, and then put it into normal operation.
6. Dirt may be stuck on the sealing surface of normally open valves. When closing, flush them with the above methods and then formally close them.
7. If the hand wheel and handle are damaged or lost, they should be equipped immediately, and can not be replaced by an adjustable wrench, so as to avoid damage to the four sides of the valve stem, ineffective opening and closing, and accidents in production.
8. Some media are cooled after the valve is closed to make the valve shrink. The operator should close the valve again at an appropriate time to keep the sealing surface free of cracks. Otherwise, the media flows through the cracks at a high speed and easily erodes the sealing surface.
9. During operation, if it is found that the operation is too laborious, the reason shall be analyzed. If the packing is too tight, it can be loosened properly. If the valve stem is skewed, notify the personnel to repair it. Some valves are difficult to open due to thermal expansion of the closing parts when they are closed; If it must be opened at this time, unscrew the bonnet thread for half a turn to one turn to eliminate the valve stem stress, and then turn the handwheel.
2、 Precautions:
1. High temperature valves above 200 ℃ must be tightened again, called "hot tightening", because they are installed at normal temperature. After normal use, the temperature rises, the bolts expand due to heat, and the clearance increases. The operators should pay attention to this work, otherwise, leakage is likely to occur.
2. When the weather is cold, the water valve shall be closed for a long time, and the accumulated water behind the valve shall be removed. Condensate shall also be discharged after the steam valve stops. The valve bottom is like a plug, which can be opened for drainage.
3. Some non-metallic valves are hard and brittle, and some have low strength. During operation, the opening and closing force should not be too large, especially not strong. Also pay attention to prevent objects from bumping.
4. When a new valve is used, the packing should not be pressed too tightly to avoid leakage, so as to avoid excessive pressure on the valve stem, accelerated wear, and difficult opening and closing.
News