Maintenance of Valve Leakage

Valve leakage occurs may due to the following five reasons: falling off of the disc, packing leakage, sealing surface leakage, leakage between body and bonnet, and leakage of sealing ring connection. For different reasons, respective measures can be taken.

Falling off of the disc

1. Do not use too much force to close valves.
2. The disc should be firmly connected with stem.
3. The fasteners used to connect disc and stem should withstand corrosion of medium and have certain mechanical strength and abrasion resistance.

Packing leakage

1. Packing with long period of use, aging and damage should be replaced in time.
2. Stems that are bent and worn should be straightened and repaired and those that are severely damaged should be replaced in time.
3. Damaged glands, bolts and other parts should be timely repaired or replaced.
4. Comply with operation procedures and operate at a uniform speed with normal force except impact handwheel.
5. Select packing materials and types according to working conditions.

Sealing surface leakage

1. Select gasket materials and types according to working conditions.
2. If the static sealing surface is corroded and of poor quality, it should be repaired and ground to meet relevant requirements.
3. Cleaning should be noticed when installing gasket. Use kerosene to clean sealing surface.

Leakage between body and bonnet

1. Improve casting quality and strictly perform hardness test according to regulations before installation.
2. The welding seam of body and bonnet composed by welding should be performed in accordance with relevant welding operation regulations.
3. It is forbidden to pile heavy objects on the valve and to hit cast iron valves and non-metal valves with hammer.

Leakage of sealing ring connection

1. If the connection surface of sealing ring is corroded, it can be repaired by grinding and bonding. And if it fails, sealing ring should be replaced.
2. Remove screws and pressure rings for cleaning and replace damaged parts. Take measures of welding and bonding to repair the parts that are severely corroded and damaged.