First, the valve leakage:
Reasons: 1. Closed is not strict 2. Joint surface damage 3. The gap between the valve core and the valve stem is too large, causing the valve core to sag or the contact is not good 4. The sealing material is bad or the valve core is stuck.
Treatment: 1. Improve operation, re-open or close 2. Disassemble the valve, re-grind the valve core and seat sealing surface 3. Adjust the gap between the valve core and the stem or replace the valve disc 4. Disassemble the valve, eliminate the cassette 5. Replace it Or surfacing seal 2, packing leakage:
Reasons: 1. The material of the packing is not correct. 2. The packing gland is not pressed or biased. 3. The method of adding packing is not correct. 4. The surface of the stem is damaged.
Handling: 1. Correct selection of packing 2. Check and adjust the packing gland to prevent pressure deviation 3. Add packing according to the correct method 4. Repair or replace the valve stem 3. Valve body leakage:
Reasons: 1. The valve body has blisters or cracks. 2. The valve body is cracked during repair welding.
Treatment: 1. Polish the suspected crack and etch it with 4% nitric acid solution. If there is crack, it can be displayed. 2. Cut and repair the crack. 4. The valve stem and its mating female thread are damaged or the stem tip is broken and the stem is bent:
Reasons: 1. Improper operation, excessive force on the switch, failure of the limit device, and over-torque protection. 2. The thread is too loose or too tight. 3. The operation is too many and the service life is too long.
Treatment: 1. Improved operation, excessive force is not available; check the limit device, check the over-torque protection device 2. Select the appropriate material, the assembly tolerance meets the requirements 3. Replace the spare parts 5. The bonnet joint surface leakage:
Reasons: 1. The bolt tightening force is not enough or tightly biased. 2. The gasket does not meet the requirements or the gasket is damaged. 3. The joint surface is defective.
Handling: 1. Retighten the bolt or make the door flange flange gap 2. Replace the gasket 3. Disassemble the door cover sealing surface 6. The valve core and the valve seat have cracks:
Reasons: 1. The quality of the joint surfacing welding is poor. 2. The temperature difference between the two sides of the valve is large.
Treatment: Repair welding with cracks, heat treatment according to regulations, light and grinding. 7. The valve core is separated from the valve stem, causing the switch to malfunction:
Reasons: 1. Improper repair 2. Corrosion of the joint between the valve plug and the stem 3. Excessive force on the switch, causing damage to the joint between the valve plug and the stem 4. The spool is loose and the joint is worn
Handling: 1. Pay attention to inspection during maintenance 2. Replace the door rod of corrosion-resistant material 3. Operation is not strong switch, or can not continue to open the valve inlet pump after full opening. 4. Check and replace damaged spare parts. 8. Valve stem lift is not working or switch Do not move:
Reason: 1. In the cold state, it is too tight to be heated and then swelled or fully opened. 2. The packing is too tight. 3. The stem clearance is too small and swells. 4. The stem and the nut are too tightly fitted, or Damage with the threaded fastener 5. Pressure of the packing gland 6. Bending of the door rod 7. The medium temperature is too high, the lubrication is poor, and the valve stem is seriously rusted.
Disposal: 1. After heating the valve body, slowly test it with force or open it tightly and then close it slightly. 2. Slightly loose the packing and test the opening. 3. Increase the valve stem clearance. 4. Replace the valve stem and the nut. 5. Re-adjust the packing gland bolt. 6. Straighten the door rod or replace it. 7. The door rod is made of pure graphite. Powder lubricant
