Valve, Plug 2 : A valve in which the closure member (plug) is rotated. This plug may be cylindrical, conical or spherical in shape, solid, or split, with a conduit bore which aligns with the seat bore in the open position. (Spec 14D)
The Mudblogger (Oilfield, Energy and Related Photographs), Oil Field Glossary, TX, USA 2014. http://mudblogger.com/oilfield-glossary/, (Oil - Amer) {777}