Globe Valve

 

Globe valve is a linear motion type of valves and is typically used in both on-off and throttling applications. They are widely used in applications where pressure drop through the valve is not a controlling factor.

These valves are generally not used beyond sizes larger than NPS 12 (DN 300) as enormous forces are exerted on the stem to open or close the valve under fluid pressures. Globe valves require high pressures on the seat to keep it closed when the fluid exerts pressure from the bottom of the disc. These valves are invariably used due to their inherent characteristics of flow to valve opening.

Direct thrust of disc is acted on seat which gives good shut off and flow characteristics. Globe valve normally offers shut off tightness of 0.01% of full flow.

They are used for both on-off and throttling applications but special types of trims are required for throttling applications where large pressure drops are involved.

When the disc is removed from the stem and allowed to rest on its own weight, globe valves can be used as non-return valves. Machining of seats is easier and cheaper compared to other types of valves.

These valves can be used in three configurations, depending upon the applications:

Tee pattern :

This type of valve has a horizontal setting of seat and the disk travels perpendicularly to it. This pattern observes large amount of pressure drop and hence used where pressure drop is not a concern.

Angle Pattern :

The flow of fluid occurs in a single 90 degree turn. This type has the capacity to handle slugging effect and is used in applications having pulsating flow.

Wye Pattern :

The seat and stem are angled at 45 degree. At full opening this gives a straight flow path and least resistance. Wye pattern have higher coefficient of flow than Angle type and are used in throttling applications.