Globe Valve Types and Parts – A Complete Guide

What is Globe Valve?

A globe valve is a linear motion valve used to stop, start, and regulate the fluid flow. The globe valve disk can be removed entirely from the flow path, or it can completely close the flow path. During opening and closing of globe valve, disc moves perpendicularly to the seat.

This movement creates the annular space between the disk and seat ring that gradually close as the valve closed. This characteristic provides the globe valve good throttling ability required for regulating the flow.

Leakage from globe valve seat is less as compared to the gate valve, mainly due to right angle contact between the disk and seat ring, which allows tighter seal between seat the disk.

Globe Valve Diagram

In the below globe valve diagram, you can see the how globe valve functions. Figure 1 below show also shows flow direction.

 Figure 1

Globe valves can be arranged in a such a way that the disk closes against the flow or in the same direction of flow.

When the disk closes in the direction of flow, the kinetic energy of the fluid helps closing but obstructs opening. This characteristic is preferable when a quick-acting stop is required.

When the disk closes against the direction of flow, the kinetic energy of the fluid obstructs closing but helps to open the valve. This characteristic is preferable when quick-acting start is required.

 Globe Valve Parts

Here in below image, you can see the globe valve parts such as Body, Bonnet, Stem, Seat, Disk, etc.

 Figure 2

 Globe Valve Disk Types

Globe valve is available in may different types of disc arrangement. Most used disk designs are listed below:

1. Ball Type
2. Needle Type
3. Composite type

Figure 3

The ball disk design is used in low-pressure and low-temperature systems. It is capable of throttling flow, but in principle, it is used to stop and start the flow.

Needle disk design provides better throttling as compared to ball or composition disk design. A wide verity of long and tapered plug disks are available to suit different flow conditions.

Composition disk is used to achieve better shutoff. A hard, non-metallic insert ring is used in composition disk design.

Depending on the type of body there are three types of globe valves;

1. Z types
2. Y types
3. Angle Types

Z types Globe Valve

The simplest design and most common type is a Z-body. The Z-shaped partition inside the globular body contains the seat. The horizontal seating arrangement of the seat allows the stem and disk to travel perpendicular to the pipe axis resulting in a very high-pressure loss.

The valve seat is easily accessible through the bonnet which is attached to a large opening at the top of the valve body. Stem pass through the bonnet like gate valve.

This design simplifies manufacturing, installation, and repair. This type of valve is used where pressure drop is not a concern and throttling is required.

Figure 4

 Y types Globe Valve

The y-type design is a solution for the high-pressure drop problem in Z-type valves. In this type, the seat and stem are angled at approximately 45° to the pipe axis. Y-body valves are used in high pressure and other critical services where pressure drop is concerned.

Figure 5

Angle types Globe Valve

The angle globe valve turns the flow direction by 90 degrees without using an elbow and one extra pipe weld. Disk open against the flow. This type of globe valve can be used in the fluctuating flow condition also, as they are capable of handling the slugging effect.