Gate valve

A Gate Valve, or Sluice Valve, as it is sometimes known, is a valve that opens by lifting a round or rectangular gate/wedge out of the path of the fluid. The distinct feature of a gate valve is the sealing surfaces between the gate and seats are planar. The gate faces can form a wedge shape or they can be parallel. Gate valves are sometimes used for regulating flow, but many are not suited for that purpose, having been designed to be fully opened or closed. When fully open, the typical gate valve has no obstruction in the flow path, resulting in very low friction loss.

Gate valves are characterised as having either a rising or a nonrising stem. Rising stems provide a visual indication of valve position. Nonrising stems are used where vertical space is limited or underground.

Bonnets provide leakproof closure for the valve body. Gate valves may have a screw-in, union, or bolted bonnet. Screw-in bonnet is the simplest, offering a durable, pressure-tight seal. Union bonnet is suitable for applications requiring frequent inspection and cleaning. It also gives the body added strength. Bolted bonnet is used for larger valves and higher pressure applications.

Another type of bonnet construction in a gate valve is pressure seal bonnet. This construction is adopted for valves for high pressure service, typically in excess of 15 MPa (2250 psi). The unique feature about the pressure seal bonnet is that the body - bonnet joints seals improves as the internal pressure in the valve increases, compared to other constructions where the increase in internal pressure tends to create leaks in the body-bonnet joint.

Gate valves normally have flanged ends which are drilled according to pipeline compatible flange dimensional standards. Gate valves are typically constructed from cast iron, ductile iron, cast carbon steel, gun metal, stainless steel, alloy steels, and forged steels.

Images of Gate Valves

See also

* Globe valve
* Ball valve
* Butterfly valve
* Control valve
* Plastic pressure pipe systems
* Needle valve
* Valve

External links

* [http://www.shipham-valves.com/gate.html Gate Valves] from Shipham Valves
* [http://www.nov.com/Products.aspx?Puid=wGKNPPbF1se9oD&nodeId=ELDTJXWWMWBWM1CW%2BWBLY6GSRYW%3D-WGKNPPBF1SE9OD Example of a gate valve from Shaffer, a subsidiary of National Oilwell Varco]
* [http://www.williamsvalve.com/gate_valves.asp Example of gate valves] from Williams E. Williams Valve Corporation
* [http://www.smidse-groenlo.nl Dutch Valve Modification Factory]