The gate valve is a tool allows the fluid flows inside the pipe or can shut off the fluid flow, it uses for ON or OFF not to regulate the pressure.
As shown in the animated figure the gate can slide between two seats to switch on the flow or switch off.
** when you use the gate valve partially open during flowing, the fluid flow make a high vibration and noise, and the gate and two seats will damage.
It is designed with many types and characteristics as per which field the gate valve will serve?
For Example
- Oil and Gas industry: most probably the fluid inside the valve contains a mix of oil and gases, and some times the flow inside the valve contains [acids, sand from well formation, H2S,...]
So the design of gate valve must consider all of theses types of substances to be stable in normal operation.
For high pressure gate valves working pressure starts from 2000 PSI up to 20,000 PSI, the valve must be designed as per API 6A standard.
Gate Valve Construction
Flange Connection:
The flange connection in high pressure equipment has been considered by API-6A, it is a strong connection with metal to metal sealing.
The flange connected with pipe by two different methods (Welded neck, and Threaded), as per API 6A standard there are two types 6B, 6BX more details review API-6A standard below.
The metal ring between two flanges located inside the groove is responsible for sealing between two flanges - Review API-6A standard for more information.
Sealing:
There are two types of sealing to prevent the fluid passing when the valve is closed:
O-Ring Sealing: as shown in the figure, you can find O-Rings between the body of the valve and the seat that contact directly with gate.
those O-Rings able to prevent fluid to pass from pipe to the valve cavity and vise versa.
Metal to Metal Sealing: this sealing between the seat and gate itself, where metal to metal sealing allows the gate sliding between two seats smoothly (Lubrication is Mandatory).
Operating Mechanism:
There are many ways and mechanisms to operate the gate valve fully opened and fully closed.
Manually: by using the hand wheel connected to screw drive which converts the rotation movement to linear movement at the gate itself, so the gate become opened or closed.
Actuator: as shown in the figure, the hydraulic actuator can operate the gate valve easily with no human touch.
just send a hydraulic signal to the actuator to open or close in case of double acting actuator.
in case of single acting actuator just one signal to open the valve and when the pressure signal released, the spring return back the valve to initially closed.
Animated Video
References
- Fluid Power with Applications, Author: Anthony Esposito, Seventh Edition
- API 6A Standard 👇👇
- WOM gate valves for Oil and Gas industry.
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