What is valve packing?
The valve type is all stem actuated control valves. It requires some form of seal that allows motion of the stem from external devices. This happens while sealing the fluid so that no leak occurs between the body of the valve and moving stem. Packing is the general term of this sealing mechanism.
Choosing of the valve packing material
There are two types of valves packing material and the most used packing material is PTFE packing. It can also be used as virgin and it is loaded with other materials such as carbon, silica and glass fiber. The other valve packaging material is graphite packing and it can withstand high pressure of temperature that goes up to the 1000 degree.
Valve material and its packing material is actually installed between the packing box and valve material which helps in preventing the outer leakage. There are many kinds of valve packaging materials such as flexible graphite pickings, vegetable fiber packing, PTFE valve packing, rubber filler, carbon fiber packing, metal and rubber valve packing and many more.
For the knowledge the valve packing materials are actually flexible graphite and PTFE and it is also noted that the packing boxes need roughness and accuracy. The stem surface dimensions and its accuracy also affect the packing seal performances.
How to do valve packing?
The valve packing must be done properly. It means that it should be compressed properly. While doing this we could prevent loss of fluid and also help in damaging the fluid stem. If the packing of the valve is very loose then the valve leaks and it affects its safety. But if the valve packing is tight then it damages the stem.
Importance of valve packing
Valve packing allows the stem to pass into the body of the valve. It does this without any loss of fluid and pressure. The packing of the valve acts as the dynamic seal that is between the bonnet and the valve stem. This valve packing is done for most of the valves to prevent leakage from the spaces that are between the bonnet and the valve stem. Mostly packing of the valve is done by the fibrous material such as Teflon and flax. It forms the seal between the internal valve parts and the outside of the stem.
Requirements for the valve packing material
The major requirements for the valve packing material includes:
1. The ideal valve packing material must be elastic and it must be deformable
2. It must be chemically inert
4. It is very much useful to withstand temperature and high pressure.
Advantages of valve packing material
1. The biggest advantages of the valve packing material is that it helps in preventing the fluid leakage
2. It also helps in preventing the dirt or any other things from entering the fluid
3. The packed glands can be used for stem sealing. It also includes many types of valves such as globe valves, ball valves and gate valves.