Gate valves are primarily designed to start or stop flow, and when a straight-line flow of fluid and minimum flow restriction are needed. In service, these valves generally are either fully open or fully closed.
The disk of a Gate valve is completely removed when the valve is fully open; the disk is fully drawn up into the valve Bonnet. This leaves an opening for flow through the valve at the same inside diameter as the pipe system in which the valve is installed. A Gate valve can be used for a wide range of liquids and provides a tight seal when closed.
Construction of a Gate valve
Gate valves consists of three main parts: body, bonnet, and trim. The body is generally connected to other equipment by means of flanges, screwed or welded connections. The bonnet, which containing the moving parts, is attached to the body, usually with bolts, to permit maintenance. The valve trim consists of the stem, the gate, the disc or wedge and the seat rings.
