Plug Valve

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 Plug Valve:


  • Plug valve is a Quarter-turn rotary motion Valve that uses a tapered or cylindrical plug to stop or start the flow. The disk is in plug shape, which has a passage to pass the flow.
  • In the open position, this bored passage is in line with the flow. When the plug is turned 90° from the open position, the solid part of the plug blocks the flow.
  • It is used in place of a gate valve where the quick operation is required. It can be used in high-pressure temperature services.
  • Plug valves are available in either lubricated or non lubricated design.
                         ***Video link of plug valve working***

Plug Valve types:

These valves classified as lubricating and non-lubricating.

1. Lubricating plug valve:
These valves use a lubricant which provided under pressure between the body seat and plug face. Lubricant provides less friction between the metal parts of the valve and increases valve life. Multiple grooves around the body and plug port opening supplied with grease prior to actuation. This lubricant (grease) seals the gap between body and plug and also seals plug motion. Grease injected for lubrication through fitting at the top of the valve stem through the check valve. The lubricant must be compatible with temperature and working fluid nature. Lubricated plug valves can be large as 24 inches and have capabilities to handle pressure up to 6000 psig.

2. Non-lubricated plug valve:
Non-lubricating plug valve uses a tapered or cone-shape that acts as a wedge and presses the sleeve alongside the body cavity. Sleeve reduces friction between the body and plug mechanism. Lift type and elastomer sleeve are the two basic types of non-lubricating plug valve. Lift type non-lubricating plug provides with a mechanically lifting arrangement to disengage tapered plug from the seating surface. Mechanical lifting accomplished with external lever or cam.
Common non-lubricating plug valves have elastomer sleeve. Elastomer sleeve is a TFE sleeve which surrounds the plug completely. It is engaged and locked in place through a metal body. This design results in a primary seal maintained between the sleeve and the plug at all times irrespective of the valve position. TFE sleeve has less coefficient of friction and also self-lubricated. These valves used where maintenance to be kept at a minimum level.

Applications of Plug Valve:

  • Plug valves use for low pressure, low temperature. While some high pressure, high-temperature designs are also available. 
  • These valves permit easy lining of the body with corrosive chemical materials such as polytetrafluoroethylene (PTFE), sulfur and hydrogen fluoride. 
  • These are ideal for on off, moderate throttling and diversion applications. 
  • They are applied in liquid and gas, vacuum, food processing, non-abrasive slurry and pharmaceutical services. Abrasive and sticky fluids can also handle with special design.

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