The body holds pressure, houses the seat and closure member, and connects to the pipe by flanges, weld ends or threads. It is cast or forged, in grades such as WCB or A105 carbon steel and CF8M or F316 stainless, and its markings show material, pressure class, size and flow direction. Body and bonnet together form the shell that a hydrostatic shell test proves.
Body casting has a weep at the bottom drain boss, tag it out and get a new valve, you don't weld on that.
Also heard as
- valve body
- shell
Related terms
Bonnet
The cover that closes the top of a valve body and carries the stem, packing and often the yoke.
Shell test
A hydrostatic pressure test of the valve body and bonnet, run with the valve partly open, to prove the shell holds.
Pressure class
The standardized rating step, such as 150, 300 or 600, that sets a valve or flange's allowable pressure at each temperature.
Seat
The surface inside a valve that the closure member presses against to stop flow.