COMMON VALVE TYPES
Plug Valves
The families that appear on first RFQs and Chinese export quotes. Shared names are not interchangeable designs.
Choosing Plug Valves
A plug valve uses a rotating plug to change the flow path. Isolation plugs, multi-port routing plugs and eccentric rotary control plugs serve different purposes. Specify the actual construction rather than using plug valve as a substitute for a flow diagram or a control requirement.
What to include in the RFQ
- Define isolation, diversion or continuous regulation and identify the required port arrangement.
- Request plug and seat materials, permitted flow direction and torque through the travel.
- For control duty, request capacity versus opening and checks for noise, cavitation or erosion.
- Confirm lubrication requirements, packing design, maintenance access and the full service envelope.
A published design example
The Neles Finetrol FC/FG family is an eccentric rotary plug control design; it should be evaluated as a control valve rather than assumed to be equivalent to every isolation plug.
Selection scenario
For a process line needing regulation with impure fluid, compare an eccentric control plug using a sizing calculation. For a routing duty, begin with the port diagram; a two-port control design cannot replace a three-way routing valve.
Common selection mismatch
A rotating plug does not make every design suitable for abrasive service or throttling. Obtain evidence for the offered trim and fluid conditions.