body The main pressure boundary of the valve, which also provides the pipe connecting ends and the fluid flow passageway as well as supporting the valve trim. [ANSI/ISA-75.05.01-2000]
body, encapsulated A body with all surfaces covered by a continuous surface layer of a different material, usually an elastomeric or polymeric material.
body, split A valve body design in which trim is secured between two segments of a valve body.
body, wafer A thin annular section body whose end surfaces are located and clamped between the piping flanges by bolts extending from flange to flange.
body, wafer, lugged A thin annular section body whose end surfaces mount between the pipeline flanges or may be attached to the end of a pipeline without any additional flange or retaining parts, using either through-bolting and/or tapped holes.
body, weir type A body that has a raised contour that is contacted by a diaphragm to shut off fluid flow.
body cavity The internal chamber of the valve body. [ANSI/ISA-75.05.01-2000]
boiler 1. A closed vessel in which water is heated, steam is generated, steam is superheated, or any combination of these, by the application of heat from combustible fuels in a self-contained or attached furnace. [ISA-77.41-1992] A typical boiler control scheme is shown in the illustration accompanying this definition. 2. The entire vessel in which steam or other vapor is generated for use external to itself, including the furnace. This includes the waterwall tubes; the firebox area, including burners and dampers; the convection area, consisting of any superheater, reheater, and/or economizer sections as well as drums, generating tubes, and headers. [ANSI/ISA-77.13.01-1999; ANSI/ISA-77.42.01-1999; ANSI/ISA-77.44-1995]
boiler drum level A water-tube boiler (not once-through) process variable that is measured and controlled by adding feedwater. Control may be single-element, two-element, or three-element; the control strategy will depend on the user’s requirements and the boiler design. Measured variables may include drum level, steam flow, feedwater flow, blowdown flow, drum pressure, and feedwater pressure.
boiler horsepower The evaporation of 34½ lbs of water per hour from a temperature of 212°F into dry saturated steam at the same temperature. Equivalent to 33,475 Btu.