Replacement of Valve Packing

Some stainless steel gate valve’s packing materials are not suitable for the valve in stock, and some are not in accordance with the medium used, so the packing needs to be replaced.

Valve manufacturer can not consider using different media. The packing box is always filled with ordinary packing, but when used, it must be suitable for the medium.

When replacing the packing, the packing should be pressed in circle by circle. The joint of each circle should be 45 degrees, and the circle should be separated by 180 degrees. The packing height should consider the space for the gland to continue to compress, and at present, the proper depth of the lower gland packing chamber should be allowed. This depth can be generally 10-20% of the total depth of the packing chamber. For valves with high requirements, such as flang stainless steel gate valve the joint angle is 30 degrees. The joint between the ring and the ring is staggered by 120 degrees.

Classification of valve packing
The filler is divided into soft packing, semi-metallic packing and metal filler according to its material.
The following is a description of the service conditions.
Plant fiber filler
It is made of hemp or cotton impregnated oil, wax or other impervious materials, and is used for low pressure valves below 100 ℃. Suitable for water, ammonia, acetic acid, caustic soda and other media.
Asbestos fiber filler
Asbestos fiber has the advantages of good heat resistance, weak acid and strong alkali resistance, high strength and good adsorption performance
Plastics and plastics impregnating fillers

YAB type nylon asbestos filler, suitable for corrosive medium, medium temperature ≤ 100 ℃, pressure ≤ 32Mpa
PTFE emulsion asbestos filler is suitable for strong corrosive medium. The medium temperature is -200 ~ 200 c, the pressure is less than 35MPa
NFS type polytetrafluoroethylene braided packing, suitable for chemicals, medium temperature of - 200 ~ 260 ℃, pressure ≤ 35MPa
Rubber filler

There are rubber cloth, rubber rod and annular rubber filler, which are used in ammonia, concentrated sulfuric acid and other media with temperature ≤ 140 ℃
Carbon fiber filler

The model is TCW type, which is made of carbon fiber braided cord and polytetrafluoroethylene emulsion. Carbon fiber filler has excellent elasticity and softness; It has excellent self-lubricating property and high temperature, and can work stably in the temperature range of - 120 ~ 350 ℃ in air, with pressure resistance ≤ 35MPa
Flexible graphite packing

Flexible graphite is widely used in petroleum, chemical industry, power generation, chemical fertilizer, medicine, papermaking, machinery, metallurgy, aerospace and atomic energy industries. Suitable for nominal pressure ≤ 32Mpa.