VALVE FUNCTIONS AND BASIC PARTS

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 Page 1