This multi-turn valve derives its name from the rotating plug which forms the closing element.The plug may be cylindrical or truncated. In the open position, the fluid flows through a hole in the plug.Lubricated plug valves rely on a sealing compound injected between the plug and the valve body, whilst sleeved plug valves are fitted with a "soft" insert between the plug and the body.

Self-Lubricated Plug Valve Class 300's specification is as follow:

Design and manufacture: API6D ANSI B16.34
Face to face dimensions: ANSI B16.10
End flange dimensions: ANSI B16.5
Test: API 6D or API598
End Flange Dimensions
RF and RTJ flange ends to ANSI B16.5 standard.
BW flange ends to ANSI B16.25 standard
Type of Construction
Lever
Connection dimensions of worm Gear actuator, Electric actuator,
Pneumatic actuator to ISO 5211 standard
Anti-static Electricity constructions "AS" and Fire-safe construction "FD"