One, the closing piece falls off produces the leakage:

Reason: 1, the operation of the bad, so that the closure of the die or more than dead point, the junction damaged and broken; 2, the closure of the connection is not strong, let up and fall off; 3, the selection of connector material is wrong, not withstand the corrosion of the media and mechanical wear. 

Maintenance method: 1, correct operation, close the valve can not be too large, open the valve can not exceed the dead center, the valve full, the handwheel should be reversed a little;  

2, closed parts and valve stem connection should be strong, threaded joints should be back parts; 

3, closed parts and valve stem connection with the fastener should withstand the corrosion of the medium, and has a certain mechanical strength and wear-resistant properties. Second, the leakage of the packing (valve leakage, filling the proportion of the largest) reasons: 1. Filler selection is not, not resistant to the corrosion of the medium, the valve is not high pressure or vacuum, high-temperature or low-temperature use; 2. Filler installation is not correct, there is a small generation of large, spiral wound joints bad, tighten down loose and other defects; 3. Filler over the use period, has been aging, loss of elasticity 4. Stem precision is not high, there are bending, corrosion, wear and other defects 5. Insufficient number of filler rings, the gland is not pressed tight; 6. The gland, bolts, and other parts are damaged so that the gland cannot be pressed tightly; 7. Improper operation, excessive force, etc. 8.  

Gland askew, gland and stem gap between too small or too large, resulting in stem wear, filler damage. Maintenance method: 1. Material and type of filler should be selected according to working conditions; 2. According to the relevant provisions of the correct installation of fillers, packing should be placed on a ring-tight, the joint should be 30 ℃ or 45 ℃ 3. The use of too long, aging, damaged fillers should be replaced in a timely manner; 4. Valve stem bending, wear after straightening, repair, serious damage should be replaced in time; 5. Filler should be installed according to the number of laps, the gland should be said evenly tight, the pressure sleeve should be more than 5mm of preload clearance; 6. Damaged gland, bolts and other parts shall be repaired or replaced in time; 7. Should observe the operating procedures, in addition to impact type Handwheel, with uniform normal strength operation; 8. 

Should be evenly symmetrical tightening gland bolts, gland and stem clearance is too small, should be appropriate to increase its clearance, gland and stem clearance is too large, should be replaced.

Leakage of sealing surface

Reason: 1, the sealing surface grinding uneven, can not form a closed line; 2, valve stem and close parts of the junction pinion shaft hanging, not positive or wear, 3, valve stem bending or assembly is not, so that the closure of skew or not in the middle of; 4, the quality of the sealing surface selection or not according to the working conditions of the selection of valve Maintenance methods: 1, according to the working conditions of the correct selection of the material and the shape of the gasket, 2, carefully adjusted, smooth operation, 3, should be evenly symmetrical screw bolts, when necessary, the use of torque wrench, preload should meet the requirements, not too large or small. There should be a certain preload gap between the flange and the threaded joint; 4. Gasket assembly should be in the right, uniform force, gasket does not allow lap and use of double gaskets, 5, static sealing surface corrosion, damage processing, processing quality is not high, should be repaired, grinding, color inspection, so that static sealing surface in line with the relevant requirements; 6, Ann When filling the gasket should pay attention to clean, the sealing surface application kerosene clear, the gasket should not fall to the ground.