Plug valves utilize conical and cylindrical plugs to stop or throttle flow in a system. The plug has an opening in the center that allows for flow through the valve in the open position when the cavity is parallel to the flow. When the controlling lever rotates, the plug inside the valve assembly turns and the cavity is perpendicular to the flow which in turn stops the flow.

Plug valve construction allows for quarter turns to completely shut off or open flow. This article covers the different types of plug valves, valve construction and components, typical applications, and maintenance and repair.