Reason：
1. Filler selection is wrong, the media is not resistant to corrosion, the valve is not resistant to high pressure or vacuum, high temperature or low temperature.
2. Filler installed wrong, there is a small generation of big, bad spiral coil connector, under the tight loose defects.
3. Filler over the use of the period, has been aging, loss of elasticity.
4. Valve stem is not high, there are bending, corrosion, wear and other defects.
5. Less than of the number of no compression gland packing ring.
6. Damaged gland, bolts, and other components, so no compression gland.
7. Improper operation, excessive force, etc.
8. Gland skew, gap between the gland and the stem is too small or too large, resulting in stem wear, packing damage.
Maintenance method:
1. The material and type of packing should be chosen according to the working condition.
2. According to the relevant provisions of the correct installation of packing, packing should be placed by pressing, joints should be 30 degrees or 45 degrees celsius.
3. The use of long, aging, damaged packing should be replaced in a timely manner;
4. Stem bending, wear and straightening, repair, serious damage to the timely replacement;
5. Packing shall be installed according to the prescribed number of turns, gland should be evenly to tight, pressure sleeve preload gap should be more than 5mm;
6. Damage to the gland, bolts and other components, should be timely repair or replacement;
7. Should comply with the operating procedures, in addition to the impact of the hand wheel, in order to uniform normal power operation;
8. Be evenly tightened symmetrically gland bolts, gland and valve clearance is too small, the gap should be suitably increased; gland and the valve clearance is too large, should be replaced.
