VALVE PARTS AND TERMINOLOGY

VALVE PARTS AND TERMINOLOGY
Port: Entrance and exit opening in the body.
Body: Pressure containing portion of valve with end connections

Disc: Linear movable element with sealing surface (gate, globe, check and butterfly)

Rotor: Rotating movable element with sealing surface (ball, plug)




Body Seat: “Stationary” sealing surface inside the body that contacts the disc or rotor

• Weld overlay (e.g., stellite)
• Integral (e.g., SS seat machined inSS body)
• Removable insert
• Soft (e.g., PTFE, rubber)

Yoke: Structure above bonnet that supports the stem and operator on an OS&Y gate or globe valve.  Is not part of the pressure boundary.  Is not needed where the valve has an inside stem design (such as under ground gate valves)
Stem: The mechanical element that connects the Disc or Rotor inside the valve with the operator outside the body of the valve.  Common stem configurations include:

• Outside stem (or screw) and yoke (OS&Y) with rising stem (shown above)
• Inside screw with rising stem
• Inside screw with non-rising stem (e.g., gate valve in underground service)

Bonnet: Cover for access opening in body.  Commonly penetrated by stem.
Backseat: Supplied on rising stem valves to seal the stem/bonnet area when valve is fully opened.  This feature permits in-service replacement of stem seals.
Gland: Bushing that compresses the packing rings when the gland flange bolts are tightened.
Valve body, valve port, disc, rotor, valve body seat, Yoke, Valve Stem, Bonnet, backseat, valve gland

Valve Trims