In this post, I want to share with you the applications of globe valves and their examples. Different from ball, plug, and gate valves, which are used to start and stop fluid flow in piping systems, globe valves are used to regulate flow. Globe valves usually should not be used for less than 20% opening for throttling, because it will increase the wear and load concentration on the seat and plug.
Application of Globe Valves for Control Valves Bypass
Typical application of globe valves is for control valves bypass. When control valve is taken out for maintenance purpose, a bypass globe valve provides continuous operation with some level of regulation.
Bypass of a control valve can be achieved by using a globe valve in process piping that should have Cv value close to but not more above the control valve. The first solution is to select control valve for the bypass line and purchase it from control valve manufacturer. Second, to purchase manual globe valve with special bore. Third, to apply restriction orifice downstream of bypass globe valve to reduce the Cv value, if the Cv value of bypass globe valve is larger than Cv value of control valve.
Stop Check Globe Valve to Prevent Backflow
Stop check globe valve work like a globe valve with additional ability to open and close the flow inside the piping system. If there is pressure drop in process line, it also shuts automatically and prevent backflow, like check valve. Stop check globe valves are available in size from ½” to 24”. The design of stop check globe valve is more complicated than conventional globe valve.
Application of Angle Globe Valves
Angle globe valves are globe valves with 90 degrees of fluid rotation. The valves were initially designed for boiler’s outlet where the steam line comes out vertically from the boiler and needs to be rotated 90 degrees. By using these valves eliminate the requirement to use an elbow to change the piping route.
Disadvantages of Globe Valves
Globe valves have several disadvantages:
- Reverse flow in globe valves can cause wearing and mechanical damage. Flow direction is only in one direction from under the disk.
- Globe valve does not perform well in dirty fluid.
- Globe valve is larger and heavier than other types of valve.
- Pressure drop through fully open globe valve is much higher than a gate valve.
- Globe valve requires high force and torque to open and to close.
- Globe valve cannot achieve tight shut off (TSO) in closed position.
That’s all about application of globe valves and their examples. I hope you find this short post useful.
Reference:
Sotoodeh, Karan. 2021. A Practical Guide to Piping and Valves for the Oil and Gas Industry. Elsevier