Cause:

1. The packing is not installed correctly, and there are defects such as replacing the big with the small, poor spiral wound joint, tightening and loosening;

2. The packing is not selected correctly, which is not resistant to medium corrosion, and is not resistant to the use of high pressure or vacuum, high temperature or low temperature of the valve;

3. The packing has expired, aged and lost elasticity. 4. The precision of the valve rod is not high, and there are defects such as bending, corrosion and wear. 5. The number of packing rings is insufficient, and the gland is not compressed;

4. The gland is skewed, and the gap between the gland and the valve rod is too small or too large, resulting in the wear of the valve rod and the damage of the packing.

5. Improper operation, excessive force, etc;

6. The gland, bolts and other parts are damaged, so that the gland cannot be pressed tightly;

Prevention and elimination methods:

1. The material and type of filler shall be selected according to the working conditions;

2. The fillers with long service life, aging and damage should be replaced in time;

3. Install the packing correctly according to relevant regulations. The packing should be placed and compacted circle by circle, and the joint should be 30 ℃ or 45 ℃;

4. Straighten and repair the valve rod after bending and wear, and replace it in time if it is seriously damaged;

5. The operating procedures shall be observed. Except for the impact handwheel, the operation shall be carried out with constant speed and normal force;

6. Damaged glands, bolts and other parts should be repaired or replaced in time;

7. The packing shall be installed according to the specified number of turns, the gland shall be tightened symmetrically and evenly, and the compression sleeve shall have a pre tightening clearance of more than 5mm;

8. The gland bolts should be tightened evenly and symmetrically. If the gap between the gland and the valve rod is too small, the gap should be appropriately increased; The clearance between the gland and the valve rod is too large and should be replaced.