The valves are used all over the world for different industrial and residential applications. The valves are used to control the fluid flow. There are multiple types of valves, and the globe valve is one of them. A globe valve is a linear flow valve used to regulate, start, or stop the fluid flow. These valves are used to completely open, close, or throttle flow applications. This article mainly explains the types, working, applications, and parts of the globe valve.
What is Globe Valve?
A globe valve is a type of valve that regulates the fluid flow by using a disc or plug. The globe valve is named because of its spherical body with two halves.
It has an inner baffle that is employed to separate the halves. It has a fixed ring seat installed in a spherical body.
The valve plug plays a big role in regulating fluid flow. This plug or disc connects with a stem. This stem further connects with a handwheel.
In the case of a manual valve, the operator rotates the handwheel to open or close the valve.
As the handwheel is rotated to open or close the valve, the plug moves vertically to the valve seat. This motion of the plug generates an annular space between the valve seat ring and the plug that slowly shuts as the valve closes. This feature of the globe valves makes them best for throttling flow applications. The major function of the globe valve is to ensure a reliable throttle and shutoff.
The main disadvantage of the globe valve is that it has a high-pressure drop than the gate valve. It has a complex design because the internal parts are installed within the valve cavity.
Globe Valve Design
The globe valve is a unidirectional valve. The globe valve has the following two major designs:
- Plug closing in the same direction of flow: If you install the valve in such a way that the valve plug shuts in the flow direction, then the fluid K.E. assists in shutting off the plug quickly. However, this design creates problems with the plug opening. This globe valve is recommended when you need a quick stop.
- Plug Closing to the oppositive flow direction: If you install a valve in which the plug closes in the opposite direction of the flow, then the fluid K.E assists in a quick opening of the valve. However, this design produces problems for valve closing. Therefore, this design is suitable when you need a rapid valve opening.
Working of Globe Valve
A globe valve is a unidirectional valve. You can install it in only one direction. It has a handwheel, disc, or plug and stem. The globe valve is used to regulate, start, and stop fluid flow. A globe valve works in the following way:
- This valve needs an operator to open, close, or regulate the flow by rotating the valve’s handwheel.
- The handwheel is connected to the stem, which is further connected to the valve disc.
- To close or reduce the fluid flow, the operator rotates the handwheel clockwise, then the handle transfers its downward motion to the stem.
- As the stem receives handwheel motion, it also moves downward and pushes the valve disc in a downward direction.
- This downward motion of the valve disc ultimately fits it between the two seats of the valve and stops the fluid flow.
- To open the valve, the operator operates the handwheel in an anticlockwise direction. In such conditions, the stem pulls the valve disc and removes the disc from the two valve seats.
- For throttling flow, the operator operates the handwheel in such a way that the valve disc or plug partially opens and partially closes.
For a better understanding of the working of the globe valve, watch the following video:
Read Also: Working of Check Valve
Types of Globe Valves
The globe valve has the following major types:
- Z Type Globe Valve
- Y-shaped Valve
- Angle Globe Valve
- Piston Globe Valve
- Needle Globe Valve
- Balanced Globe Valve
1) Z Type Globe Valve
The Z-body valve is one of the most famous types of globe valves. It is one of the simplest designs.
This valve has a Z-shaped partition inside the spherical housing. This Z-shaped partition has a seat.
The valve seat has a horizontal seating arrangement. This arrangement permits the disc and stems to move perpendicularly to the pipe axis, which leads to high-pressure losses.
The stem goes through the bonnet. This bonnet connects with the large opening on the head of the valve housing. This arrangement generates a symmetrical design that simplifies the maintenance, installation, and manufacturing of the valve.
The Z-shaped globe valves are used when pressure loss is not an issue, and throttling is needed.
Read Also: Different Types of Valves
2) Y-shaped Valve
The Y-shaped globe valves are used to control the high-pressure drop. In this design, the stem and seat rotate at an angle of approx. 45° to the pipe axis.
These valves are utilized for high-pressure and other major applications where pressure drop is a problem.
The Y-shaped globe valves are best suitable for high-temperature and high-pressure applications. The design of these valves helps to reduce the stress on the valve components and permits easy maintenance.
They are most commonly used in chemical processing, petrochemicals, oil and gas, and power generation applications.
3) Angle Globe Valve
These valves can turn the flow direction by 90° without utilizing any additional pipe weld or elbow. The disc of this valve opens in the opposite direction to the flow. These types of globe valves can handle the effects of slag. They can also use in variable flow conditions.
A main advantage of the angle globe valve is that it can be used both as a piping elbow and a valve. Under moderate temperature, pressure, and flow conditions, angle valves are very similar to normal globe valves.
4) Needle Globe Valve
It contains a needle-shaped, slender plug that ensures precise flow control, particularly in low-flow conditions. These valves are usually found in instrumentation and sampling systems.
5) Piston Globe Valve
These types of valves use a piston-like plug rather than a traditional disc. This design allows improved flow control and better seal, making it ideal for high-temperature and high-pressure applications.
6) Balanced Globe Valve
It contains a pressure-balanced design that helps to minimize the force needed to open and close the valve. The balanced plug arrangement plays a big role to reduce the operating torque, making it easier to operate even under high differential pressures.
Read Also: Working and Types of Butterfly Valves
Parts of Globe Valve
The globe valve has the following major components:
- Disc
- Seat
- Stem
- Packing
- Bonnet
- Housing or Body
- Cage
- Handwheel or Actuator
1) Disc
The disc is one of the most vital parts of the globe valve. It plays a big role in the throttling, opening, or closing of the fluid flow. It connects with the valve stem. The stem transfers the handwheel motion to the disc. As the disc gets motion, it opens or closes the fluid flow.
The globe valve has the following major designs of discs:
- Plug disc: The plug disc design delivers more excellent effects than the composition or ball design. This disc has multiple designs and long service life.
- Composition disc: It has a non-metallic, rigid insert ring on the disc. This design provides a tight and leakage-free closure.
- Ball disc: This design of the disc uses for low-temperature and low-pressure applications. It has a throttling flow function, but most commonly, it uses for opening and closing the flow.
2) Seat
This component of the globe valve provides a replaceable, uniform, and stable shutoff surface. The globe valves have two seats. A valve seat is a place where the disc fits and stops the fluid flow.
The valve seat can also be screwed and threaded within a thread cut in the valve body area. This arrangement makes the removal of the seat ring difficult during valve repair or service. The seat ring is generally declined over the seating surface to guide in the final phases of valve closing.
Some globe valves also contain backseats in the bonnet. As the valve fully opens, this arrangement provides a tight seal between the bonnet and the stem to stop the system’s pressure build-up against the valve packing.
3) Stem
The valve stem acts as a connector between the valve handwheel and the disc. It connects the disc to the handwheel. When the operator turns the handwheel, the stem takes motion from the handwheel, transfers this motion to the disc, and rotates it to start or close the fluid flow.
The manually operated valves have threaded steam, but the actuator-controlled valves most commonly have smooth stems.
The smooth surface stem has threads on both ends to ensure a connection between the valve disc and the handwheel. This stem must have high tensile strength during the valve opening, while it must also contain high compression pressure during the valve closing.
It should have a straight design or lowest run out to provide an excellent shutoff. This low run-out reduces the wear and tear of the packing installed inside the bonnet. The packing ensures a leak-free seal. The stem can be shielded over the packing nut to stop the foreign matter from going into the packing, which can produce wear.
Read Also: Working of Plug Valve
4) Packing
A packing material uses to cover the smooth stem. This packing uses to stop fluid leakage from the valve. The packing is made of wearable material. You must change it during valve maintenance.
5) Bonnet
This component of the globe valve delivers a leak-free seal for the valve housing. The stem’s threaded part inserts into the bonnet via a hole. The stem threads make contact with the corresponding bonnet threads.
The globe valves have the following major designs:
- Screw-in Bonnet: The screw-in bonnet has a very simple construction. It provides a tight pressure seal.
- Union Bonnet: Union Bonnets are best for systems that require regular cleaning or inspection. These designs strengthen the valve body.
- Bolted Bonnet: Bolted bonnets are employed for high-pressure applications. The packing of the bonnet has a wear-resistant material that ensures a tight seal between the stem and bonnet.
- Pressure-Seal Bonnet: These bonnets are most commonly employed for high-pressure and high-temperature services.
- Welded-Bonnet: These bonnets have low weight than the bolted-bonnet designs. These are used for valves where dismantling is not needed.
6) Housing or Body
The body is a major part of the valve. It surrounds all the internal parts of the valves. It prevents the internal parts from any damage due to any falling object on the valve.
7) Cage
The cage is also a major part of the globe valve. It surrounds the valve disc. It is positioned within the valve body. When the disc moves, more opening inside the cage exposes, and the flow rate increases.
The cage opening arrangement and design significantly disturb the fluid flow (the flow properties of different fluids within a certain pressure and temperature range). The cage also uses to guide the disc into the valve seat for a good seal and also uses for replacing the valve bonnet guide.
8) Handwheel or Actuator
A handwheel is employed for the manually operated valves, while an actuator is employed for the automatic valves.
A handwheel or actuator plays a big role in the valve opening, closing, and throttling. When the operator wants to open or close the valve, he turns the handwheel in a clockwise or anticlockwise direction. When the handwheel rotates, it transfers motion to the disc via a stem.
For the proper operation of the globe valve, you need to repair or maintain it properly.
Read Also: Working of Diaphragm Valve
Globe Valve Symbol
Each type of valve has a different symbol. This symbol represents a specific type of valve. The globe valve has the below-given symbol:
Advantages of Globe Valve
- This type of valve has excellent closure ability.
- It has easy maintenance than the ball valve.
- It has easy construction than the ball valve.
- These valves are best suitable for throttling flow.
- They have a shorter stroke than gate valves.
- A globe valve has faster operation than a gate valve.
Disadvantages of Globe Valves
- These valves have a high-pressure loss.
- They require high force to seat the valve.
- Obstructions and channel discontinuities can cause a large pressure drop.
- Pulsations and shocks in large high-pressure pipes can damage internal decorative parts.
- They have a high weight.
- They have more complex construction than the gate valves.
- These valves generate very more noise than the gate valves.
- They have high maintenance and installation costs than gate valves.
- More large or greater power is required to open and make noise during operation.
- These valves have high-pressure loss compared to the ball valve and gate valve.
- You can install it in just one direction.
Applications of Globe Valves
- Globe valves are used in water-cooling systems.
- Globe valves are employed in power plants to regulate the flow of cooling water, steam, and feedwater.
- Globe valves are employed in food processing, pharmaceutical, petrochemical, and chemical industries to control the flow of steam, gases, and liquids.
- These types of valves are used in heater drains, main steam vents, and drain systems.
- These are widely employed in the plumbing industry.
- Globe valves are used in HVAC systems to control and balance the flow of steam, hot and cold water, or glycol mixtures.
- They are used in water treatment plants to control the flow of water and chemicals.
- These valves are used in the oil and gas industries to regulate the fluid flow in refineries, pipelines, and production facilities.
Globe Valve Vs. Gate Valve
The main difference between a globe valve and a gate valve is given below:
| Globe Valve | Gate Valve |
|---|---|
| A globe valve uses to open, close, or throttle the flow. | A gate valve is only used to open or close the fluid flow. It can’t be used for flow regulation. |
| It is a unidirectional valve. | It is a multi-directional valve. |
| These valves have complex construction because all their internal are installed inside the valve cavity. | These have simple construction because all their parts are located on the top of the valve body. |
| The globe valves have more costs than the gate valves. | The gate valve has a low cost. |
| It has complex maintenance. | It has easy maintenance. |
| It has a high-pressure drop. | The gate valve has a low-pressure drop than the globe valve. |
| These have a complicated design. | These have an easy construction. |
Read Also: Working of Gate Valve
Globe valve Vs Ball valve
The main difference between a globe valve and a ball valve is given below:
| Globe Valve | Ball Valve |
|---|---|
| A globe valve is best suitable for opening, closing, and regulating flow. | A ball valve is best for open and close services. |
| A globe valve uses a disc to open, close, and regulate the flow. | A ball valve uses a ball to start and stop the flow. |
| You can use it for throttling flow. | It can’t be used for throttling flow. |
| The disc and stem of this valve move vertically. | It can’t be used for the throttling flow. |
| Globe valves are less durable and reliable than ball valves. | These are highly reliable and durable. |
| A globe valve has a high-pressure drop. | A ball valve has a very low-pressure drop. |
| It is a linear motion valve. | It is a rotary motion valve. |
| It has an easy design than the ball valve. | It has a complex design. |
| These valves have low costs than the ball valves. | These have high costs. |
FAQ Section
What is a globe valve used for?
A globe valve is used to open, close or throttle flow. There are manual or automatically operated valves. Globe valves are most commonly used in chemical industries, power plants, water treatment plants, HVAC systems, the oil and gas industry, and pulp and paper industries.
Why globe valve is used in petroleum industry?
A globe valve uses for throttling and isolation applications. It has a simple linear motion. Therefore, it quickly opens and closes the fluid flow. It provides a tight closure. Therefore, globe valves are used in petroleum industries.
What are the types of globe valves?
- Z-type globe valve
- Y-shaped valve
- Angle globe valve
- Piston valve
- Needle valve
- Balanced valve
How does a globe valve work?
A globe valve works by utilizing a flexible plug or disc. This disc or plug can be lowered or raised inside the valve’s body. As the operator rotates the handwheel to open the valve, the disc moves away from the seating surface, permitting fluid to flow by the valve. When the operator rotates the handwheel to close the valve, the disc makes contact with the seating surface and stops the fluid flow.
Are globe valves suitable for high-pressure applications?
Yes, some types of globe valves are designed for high-pressure applications. The pressure rating, valve design, and valve material determine the appropriateness of a globe valve for high-pressure use.
Can globe valves be used for gas applications?
Yes, you can use the globe valves for gas applications. These valves are ideal to regulate the flow of different gases, such as natural gas. However, it is important to select a valve according to the application requirements to ensure proper sealing and efficient performance.