One, valve leakage:
Reason：
1. Close LAX
2. Joint Surface Damage
3. Valve core and stem clearance too large, causing the spool or contact is not good
4. Bad sealing material or valve core card astringent.
Processing：
1. Improve the operation, turn it back on or off
2. Valve disintegration, valve core, valve seat sealing surface grinding
3. Adjust spool and stem clearance or replace disc
4. Valve disintegration, eliminate the card astringent
5. Re-replacement or surfacing seal ring
Ii. Packing Leakage:
Reason：
1. The filler material is not right
2. The packing gland does not press tight or presses the deviation
3. The method of loading is not correct
4. Valve STEM Surface damage
Processing：
1. Correct selection of Filler
2. Check and adjust packing gland to prevent bias
3. Add the filling material in the correct way
4. Repair or replacement of stem
Third, valve body leakage:
Reason：
1. The valve body has the sand hole or the crack
2. Valve Body repair welding when the crack
Processing：
1. For the suspected crack at the polished, with 4% nitric acid solution etching, if there is a crack can be displayed
2. The crack place carries on the Wabu treatment.
Four, the stem and its matching thread mother screw damage or stem head broken, stem bending:
Reason：
1. Improper operation, switch force too large, limit device failure, over torque protection not action.
2. Thread with too loose or too tight
3. Excessive operation and long service life
Processing：
1. Improve the operation, not too much force, check the limit device, check the Torque protection device
2. Selection of materials suitable, assembly tolerances meet the requirements
3. Replacement of spare parts
V, bonnet combination surface leakage:
Reason：
1. The bolt tightness is not enough or tight
2. Gasket does not meet the requirements or gasket damage
3. Defective interface
Processing：
1. Tighten the bolts or make the Mengefalan clearance consistent
2. Replace the gasket
3. Disassemble and repair the seal surface of the door cover
Six, valve core, valve seat with crack:
Reason：
1. Bonding surface surfacing quality is poor
2. The valve side temperature difference is big
Processing：
For the cracks in the repair welding, according to the provisions of heat treatment, car light, and grinding.
Seven, valve core and STEM detachment, resulting in switch failure:
Reason：
1. Improper repair
2. The valve core and the valve Stem Union place is corroded
3. The switch force is too big, causes the valve core and the stem Union place to be damaged
4. Valve Core Non-return gasket loose, connection part wear
Processing：
1. Attention check during overhaul
2. Replace the corrosion resistant material door lever
3. Operation is not a strong switch, or can not open after the opening of the valve import pump
4. Check and replace damaged spare parts
Eight, valve stem or switch does not move:
Reason：
1. Cold state is too tight when heated after the expansion of death or after full open too tight
2. Packing pressed too tightly
3. Valve stem clearance is too small and swollen death
4. Valve stem and silk mother with too tight, or with the wire buckle damage
5. Packing Gland Press deviation
6. Door Bar Bending
7. Medium temperature is too high, bad lubrication, valve stem serious rust
Processing：
1. After heating the body to slowly drive or open the foot and then slightly close.
2. Slightly loose packing gland after drive
3. Increase valve stem clearance properly
4. Change stem and silk mother
5. Readjust Packing gland bolts
6. Straightening Door bar or replacement 7. The door rod uses the pure graphite powder to make the lubricant