Causes of leakage at the valve packing: 
1. The packing is selected improperly, it is not resistant to the corrosion of the medium, and it is not resistant to the use of high pressure or vacuum, high temperature or low temperature of the valve ; 
2. The packing is not installed properly, and there is a problem that the small packing is large and the spiral coiled joint is bad. Tight loose and other defects 
3, filling more than the use of the period, has been aging, loss of elasticity 
4, the valve stem accuracy is not high, there are bending, corrosion, wear and other defects 
5, the number of filling cycles, the gland is not compressed; 
6, cover, Damage to bolts and other components, so that the gland can not be compressed; 
7, improper operation, excessive force, etc.; 
8, the lid is inclined, the gap between the gland and the valve stem is too small or too large, resulting in the valve stem wear, damaged packing . 
Prevention and elimination methods: 
1. The materials and types of 
packing should be selected according to the working conditions; 2. The packing should be properly installed according to the relevant regulations. Packing should be placed on a circle by pressing, and the joints should be 30°C or 45°C; 
3. Use The fillers that are too long, aging and damaged shall be replaced in time. 
4. The valve stems shall be straightened and repaired after they are bent and worn. The damaged ones shall be replaced in time; 
5. The fillers shall be installed according to the specified number of turns. It is said to be evenly tightened, and the press sleeve should have a pre-tightening gap of 5 mm or more; 
6. The damaged glands, bolts and other parts should be promptly repaired or replaced; 
7. The operating procedures should be followed except for the percussive hand wheel. The uniform normal force operation; 
8, should be evenly and symmetrically tighten the gland bolt, the gap between the gland and the stem is too small, should increase the gap; the gap between the gland and the stem is too large and should be replaced.