How to operate the valve correctly

When we operate the valve, in many cases, the system is not running properly due to improper operation, and sometimes there are safety hazards. So how do we operate the valve correctly? In addition to proper installation and maintenance, it is also important to operate:
Precautions:

1. The high temperature valve above 200°C is at room temperature during installation, but after normal use, the temperature rises, the bolt is heated to expand, and the gap increases, so it must be tightened again, which is called “thermal tightening”. The operator should pay attention to this work. , otherwise leakage is likely to occur.

2. When the weather is cold, the water valve is closed for a long time, and the water behind the valve should be removed. After the steam valve is stopped, the condensed water should also be removed. The bottom of the valve is like a plug, which can be opened to drain.

3. Non-metallic valves, some are hard and brittle, and some are low in strength. When operating, the opening and closing force should not be too large, especially not violent. Also be careful not to bump objects.

4. When the new valve is used, the packing should not be pressed too tightly, so as not to leak, so as to avoid too much pressure on the valve stem, speed up the wear and tear, and it is difficult to open and close.

Manual valve opening and closing:

1. The manual valve is a widely used valve. Its handwheel or handle is designed according to ordinary manpower, considering the strength of the sealing surface and the necessary closing force. Therefore, it is not possible to use a long lever or a long wrench to move the board. Some people are accustomed to using a wrench, and they should pay strict attention not to use too much force, otherwise the sealing surface will be easily damaged, or the handwheel and handle will be broken.

2. When opening and closing the valve, the force should be stable and not impacted. Some components of high-pressure valves that are opened and closed by impact have already considered this impact force and cannot be equal to ordinary valves.

3. For the steam valve, it should be pre-heated before opening, and the condensed water should be removed. When opening, it should be as slow as possible to avoid water hammer.

4. When the valve is fully opened, the handwheel should be reversed a little so that the threads are tightly tightened to avoid loosening and damage. For rising stem valves, remember the stem position when fully open and fully closed to avoid hitting the top dead center when fully open. And it is convenient to check whether it is normal when fully closed. If the valve does fall off, or if there is a large debris embedded between the valve core seals, the position of the valve stem will change when it is fully closed.

5. When the pipeline is first used, there is a lot of internal dirt, the valve can be slightly opened, and the high-speed flow of the medium can be used to flush it away, and then gently close (can not close quickly or violently to prevent residual impurities from pinching the sealing surface ), turn it on again, repeat this many times, rinse off the dirt, and then put it into normal work.

6. For normally open valves, there may be dirt on the sealing surface. When closing, use the above method to flush them clean, and then officially close them tightly.

7. If the handwheel and handle are damaged or lost, they should be assembled immediately, and can not be replaced with a flexible wrench, so as to avoid damage to the valve stem, ineffective opening and closing, resulting in accidents in production.

8. Some media cool down after the valve is closed to shrink the valve. The operator should close it again at an appropriate time, so that the sealing surface does not leave a slit. Otherwise, the medium flows through the slit at a high speed, which is easy to be eroded. Sealing surface.

9. During operation, if it is found that the operation is too laborious, the reason should be analyzed. If the packing is too tight, it can be loosened appropriately. If the valve stem is skewed, the personnel should be notified for repair. For some valves, when the valve is closed, the closing member is heated and expanded, which makes it difficult to open; if it must be opened at this time, the bonnet thread can be loosened by half a turn to one turn to eliminate the stress of the valve stem, and then the hand wheel is turned.

The above tells you how to operate the valve correctly from two aspects: one, precautions, and two, the opening and closing of the manual valve. I hope you read it carefully to avoid potential safety hazards in the follow-up life and production.