Valves
DOE-HDBK-1018/2-93
VALVE FUNCTIONS AND BASIC PARTS
VALVE FUNCTIONS AND BASIC PARTS
Valves are the most common single piece of equipment found in DOE facilities.
Although there are many types, shapes, and sizes of valves, they all have the
same basic parts. This chapter will review the common parts and functions of a
valve.
EO 1.1
DESCRIBE the four basic types of flow control elements
employed in valve design.
EO 1.2
DESCRIBE how valve stem leakage is controlled.
EO 1.3
Given a drawing of a valve, IDENTIFY the following:
a.
Body
b.
Bonnet
c.
Stem
d.
Actuator
e.
Packing
f.
Seat
g.
Disk
Introduction
A valve is a mechanical device that controls the flow of fluid and pressure within a system or
process. A valve controls system or process fluid flow and pressure by performing any of the
following functions:
Stopping and starting fluid flow
Varying (throttling) the amount of fluid flow
Controlling the direction of fluid flow
Regulating downstream system or process pressure
Relieving component or piping over pressure
There are many valve designs and types that satisfy one or more of the functions identified
above. A multitude of valve types and designs safely accommodate a wide variety of industrial
applications.
Regardless of type, all valves have the following basic parts: the body, bonnet, trim (internal
elements), actuator, and packing. The basic parts of a valve are illustrated in Figure 1.
Rev. 0
ME-04
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