Gate valves consist of valve body, bonnet and trim (disk). Gate valve bodies are generally bolted, flanged to pipeline or equipment and still able to do maintenance. The valve trim includes stem, disc and seat can be removed by unbolting the bonnet.
Gate valves are primarily designed to start and stop flow. The valves are designed for flow in a straight – line and full-area flow to minimize the pressure drop. Gate valves usually operate either fully open or fully closed. The valves open and close in a linear motion as the disk go ups or downs. Gate valves are usually used in liquid application because it has a tight seal when the valves are fully close.
Typically there are three types of gate valves: Solid Wedge, Flexible Wedge and Split Wedge Gate Valve. Each design operated differently and has its benefits.