What is the main function of packing in a gate valve?
What is the main function of packing in a gate valve?
Regardless of valve type, all stem-actuated control valves require some form of seal allowing motion of the stem from some external device (an actuator ) while sealing process fluid so no leaks occur between the moving stem and the body of the valve. The general term for this sealing mechanism is packing.
How do you maintain a gate valve?
Maintenance
- Cycle the valve at least once a month if not used regularly.
- Relieve the system pressure before performing any maintenance.
- To remove from pipework reverse the installation sequence (above).
- Replace valve gate by removing the top body (bonnet) and stem.
What is PTFE packing?
PTFE Packing or Teflon Packing is braided with high purity PTFE (Polytetrafluoroethylene, Teflon) filament. PTFE material has a low friction and excellent resistance to chemicals.
How often should valve packing be replaced?
every 2 to 3 years
Replacement Procedure for Valve Stem Packing The stem packing should be replaced preferably every 2 to 3 years even though valves have no failure such as leakage. It is required to reduce valve operating torque and to prevent stem wear.
How do you change a valve pack?
Shut off the water supply to the line that feeds to the leaking valve. The packing cap can be located just below the handle. The packing material is behind the bonnet nut. Fresh packing should be wrapped around the stem counterclockwise three times.
What is the difference between Teflon and PTFE?
Essentially, the only difference lies in the name. PTFE is the shortened name of the chemical polytetrafluoroethylene, and Teflon is the trade name of the same polymer. If you are looking for a highly flexible, non-stick material that is chemical, electrical and thermal resistant, look no further than PTFE.
Which is better graphite or Teflon packing?
Graphite packings can be treated with PTFE to get better benefits such as preventing colour contamination, gaining better stability etc. Both graphite, as well as PTFE packings, are cost-effective as they bothare durable and require low maintenance.