Plug valves are one of the most popular category of pipe vales used in variety of applications. Also known as cock or stop-cock valves, plug valves have been in use since a long period of time. Infact, they were developed for use in citywide Roman plumbing systems and remain as one of the most widely used valves for both on/off and throttling services. They are a kind of rotational motion valves which are used to stop or start fluid flow. They are so called because of the shape of the disk, which resembles a plug.
