Gate Valves are one of the most commonly used valves worldwide. They are used above and below ground across multiple applications including oil and gas industry, pharmaceuticals, manufacturing, automotive, and marine. They act as isolation valves to a system by either allowing or preventing flow through manual operation. In this way, Gate valves are designed to be either fully open or fully closed and should not be used as control or regulating valves.
Gate valves are often used when minimum pressure loss and a free bore is needed as when fully open, a Gate Valve is designed to give no obstruction which results in a very low pressure loss. Futhermore, the Gate Valve mitigates the effects of Water Hammer as its threaded operation means it opens and closes slowly.
Gate valves can be used for numerous types of applications, including water supply, gas supply, wastewater treatment and fire protection. They are particularly applicable in high pressure, high temperature environments.
Types of Gate Valve
There are three main variations on the main design of a Gate Valve. Parallel or Wedge Shaped Discs, Metal or Resilient Seated and Rising and Non-Rising Stems.
Parallel and Wedge-Shaped Gates use a variation on the disc inside the Gate Valve. A Parallel Gate Valves uses a flat disc between two parallel seats and the Wedge-Shaped Gate Valve uses an inclined disc which resembles a wedge.
Metal Seated Gate Valves use a depression in the base of the Gate Valve in which the disc will sit when fully closed. A Resilient Seated Gate Valve has a plain valve bottom allowing free passage for the fluid and any suspended matter.
Rising stems are fixed to the disc and so move with the disc when the valve is operated. Non-rising stems are threaded into the disc, and the rotatation of the Valve handle will only move the disc.
Gate Valves should not be used to control or regulate flow. It provides no accuracy in its operation to peform this role. Furthermore partially opened valves may cause erosion of the discs and seat. Vibration resulting from the flow may also result in degredation of the valve as a whole.