Common valve failure and handling

Common valve failure and treatment First, the valve leakage: The reason: 1. The valve body with trachoma or cracks; 2. Valve body pull crack treatment: 1. On the suspected crack polished, with 4% nitric acid solution etching , If there is a crack can be displayed; 2. Crack at digging treatment. Second, the stem and nut thread with its damaged or broken stem, stem bending: Reason: 1. Improper operation, the switch force is too large, limit device failure, torque protection is not action. ; 2. The thread is too loose or too tight; 3. The number of operations is too long, the service life is too long Processing: 1. Improve the operation, not too much force; check the limit device, check the torque protection device; 2. Select the appropriate material , Assembly tolerances to meet the requirements; 3. Replacement of spare parts Third, the valve cover with leakage: reasons: 1. Bolt tension is not enough or tight; 2. Gasket does not meet the requirements or gasket damage; 3. Defective bonding surface: 1. Tighten the bolts or make the flange of the door cover the same; 2. Replace the gasket; 3. Disassemble the sealing surface of the door 4. Valve leakage: Reason: 1. Strict closure; Spool valve stem and valve clearance is too large, causing the spool drooping or contact is not good; 4. Bad sealing material or spool jam. Treatment: 1. To improve the operation, re-open or close; 2. The valve disintegration, valve core, valve seat seal surface re-grinding; 3. Adjust the valve stem and valve stem clearance or replace the valve; 4. The valve disintegration, 5. Re-replacement or surfacing seals Fifth, the valve stem and valve stem from the switch, causing the switch failure: Reason: 1. Improper repairs; 2. The valve stem and stem corrosion; 3. Switch force is too large, resulting in valve The core and the valve stem is damaged at the junction; 4. The spool backstop gasket loose, connecting parts wear and tear treatment: 1. Maintenance pay attention to check; 2. Replace the corrosion-resistant door material; 3. The operation is not strong switch, Or open the valve can not be fully open; 4. Check the replacement of damaged spare parts Sixth, the valve core, the seat is cracked: Reason: 1. The quality of bonding surface with poor welding; 2. Valve temperature difference on both sides of the deal: Welding, according to the provisions of heat treatment, car light, and grinding. Seven, valve stem lifting or switching does not work: Reason: 1. cold state is too tight after the heat expansion or death after the full open too tight; 2. packing too tight; 3. Stem clearance is too small 4. Stem and nut mating too tight, or with the threaded damage; 5. Packing gland pressure partial; 6. Door bending; 7. Medium temperature is too high, poor lubrication, the valve stem serious rust treatment: 1. The valve body heated slowly after the test open or open enough and tight time off; 2. A little loose packing gland after the trial open; 3. Appropriate to increase the stem gap; 4. Replace the stem and nut; 5. Re-adjust the packing gland bolts; 6. Straighten the door or replacement; 7. Gate rod with pure graphite powder as lubricant. 8. Leakage of Packing: Reason: 1. The packing material is wrong; 2. The packing gland is not pressed Tight or partial pressure; 3. The method of adding packing is wrong; 4. Stem surface damage treatment: 1. The correct choice of packing; 2. Check and adjust the packing gland to prevent pressure deflection; 3. According to the correct method of packing 4. Repair or replace valve stem

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