Globe Valves
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Globe valve is a linear motion valve which is used to start, stop and regulate flow in a pipeline. It consists of a movable disc that connects to a steam which allow user to regulate the flow by rotating the wheel handle following the label of open and close on it. The valve direction arrow is embossed on the valve body to show flow direction.
The disc can close the flow path completely or remove entirely from the flow path. It moves perpendicularly to the seat during valve operation. The movement creates the annular space between seat and disc that gradually closes as the valve. It provides the valve a good throttling ability required in regulating the flow. Throttling valves is used to control flow rates by throttling flow straight or in a bypass line. |
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Product Specifications
For more information on the individual product specifications, please click on the links below:
What are globe valves
1. What is Globe Control Valve?
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With the right angle contact between the seat and disc, this will provide a better sealing between both main parts and the possibility of leaking will be decreased. The valve design restricts the flow of fluid by altering the distance between the seat and the movable disc. Fluid flows through a hole in the middle of the seat when the valve is at an open position.
Conventional valves may be used for throttling and isolation services. It is named as globe valves as the halves of the body are designed in a spherical shape which are separated by an internal baffle. Nowadays, many new globe valves do not have much of a spherical shape. |
ANSI 150# SS316 Globe Valve
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Globe valve has different types of disc and there are shown as table per below:
Ball Type |
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Needle Type |
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Composition Type |
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2. Are globe valves directional?
Globe valve is installed in the proper relation to system flow application as indicated by the flow direction arrow from inlet to outlet marked on the valve body. The flow is unidirectional and install with pressure side or inlet under the seat. A globe valve has several main key parts:
2.1 Body: The body is important as it is the main pressure function of valve and the easiest to identify as it forms the mass of the valve. It includes all the valve’s internal important parts that will contact with the substance which is controlled by the valve. The body is connected to the bonnet and it provides containment to the gas or fluid that is being controlled.
Globe valve is installed in the proper relation to system flow application as indicated by the flow direction arrow from inlet to outlet marked on the valve body. The flow is unidirectional and install with pressure side or inlet under the seat. A globe valve has several main key parts:
2.1 Body: The body is important as it is the main pressure function of valve and the easiest to identify as it forms the mass of the valve. It includes all the valve’s internal important parts that will contact with the substance which is controlled by the valve. The body is connected to the bonnet and it provides containment to the gas or fluid that is being controlled.
Threaded End SS316 Globe Valve
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2.2 Bonnet: It allows a leak proof termination for the valve body and the threaded section of the stem flow through a hole with matching threads in the bonnet. There are few options of bonnet: screw-in, union or bolted bonnet. Screw-in bonnet is the common and simplest bonnet type, it offers a durable and pressure tight sealing. Union bonnet is suitable for application that requires frequent inspection, cleaning or repairing. It gives the body added strength. The bolt attached to the bonnet is used for larger or higher pressure applications. The bonnet contact packs a wearable material that maintains the seal between the bonnet and steam during valve operation.
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2.3 Disc or plug: Plugs are used to control the throttling of flow. They are connected to the stem via sliding or screwing up and down method. There are two types of plug, balance or unbalance type. Unbalance plug are solid. It is used with smaller valves size with low pressure drops across the valve. The design is simple and has low cost with one possible leak path at the seat. This design has limited size constraint with large unbalance plug the forces needed to seat and hold the flow often becomes impractical. Holes are found throughout the balance plugs so the valve is easier to shut off as the plug does not have the need to overcome the static forces. A second leak path is created between the plug and the cage but this causes the cost generally higher.
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2.4 Stem: The stem serves as a connector from the hand wheel handle to the inside of the valve. Stems are smooth for threaded manual valve or actuator controlled valve. The smooth stems are surrounded by packing material to prevent valve leaking. The packing is a wearable material and can be replaced during maintenance. With a smooth stem, the ends are threaded to allow connection to the plug and the hand wheel. The stem is unable to withstand a large amount of compression force during valve closure. However, it has high tensile strength during valve opening. The stem must stay straight or on low run out in order to ensure good valve closure. The minimum run out minimizes wear of packing contained in the bonnet. It provides the sealing against leakage.
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ANSI 150# Cast Iron Globe Valve
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2.5 Seat: The seat ring provides a uniform, stable and replaceable shut off surface and it is screwed in or torqued. This pushes the cage down on to the lip of the seat and holds it firmly to the valve body. Seat is threaded and screwed into a thread cut in the same area of the body. It increases the difficulty of removing the seat ring during maintenance. At the final stage of valve closing, the bevelled end seat rights located at the seating surface will provide guidance on the closure of the valve.
3. Why is it called a globe valve?
The globe valve body are designed in several types and the most common types are Z-type, Y-type and angle type.
The globe valve body are designed in several types and the most common types are Z-type, Y-type and angle type.
- Z-type/Tee pattern: This is the most common and simplest type as a Z-shaped partition inside the globular body contains the seat. The horizontal seating arrangement allows the disc and stem to move at a perpendicular to the pipe axis resulting in a very high pressure loss. The seat can be easily accessible through the bonnet and attach to a huge opening at the top of the valve body. When the operation pressure dropped, it does not affect the valve operation while throttling is required.
ANSI 150# Cast Steel Globe Valve
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4. How does a globe valve work?
The valve plug is guided by the stem to maintain alignment with the centreline of the seat and valve is at open position when the plug and stem lift up from original place. There are two types of port design for globe valve.
The valve plug is guided by the stem to maintain alignment with the centreline of the seat and valve is at open position when the plug and stem lift up from original place. There are two types of port design for globe valve.
- Standard port-guided: The seat ring acts as a guide for the plug to ensure the centre-lines of the plug and seat is aligned. The stem may be made smaller in diameter size, so that it would minimize sliding friction and improves control behaviour. There will be only one force generated by the process working pressure.
- Double-ported: Globe valve that uses a pair of plugs and a matching pair of seats to throttle fluid flow. Differential pressure of the fluid process between inlet and outlet across a valve will generate a force parallel to the stem. There will be two opposed force vectors, one generated at the lower plug and another created at the upper plug. If the plug areas are roughly equal, the forces will likewise be about the same and therefore nearly cancelled. This makes the valve easier to actuate.
5. Where is a globe valve used?
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The globe valve is used in application such as below:
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ANSI 150# Forged Steel Globe Valve
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Globe design valve is used for throttling flow control and by moving the disc against the flow stream, valve shutoff is achieved. The flow pattern through a globe valve changes in direction and will cause high pressure drop which will result in greater resistance to flow. The globe valve is a good valve option to apply in high pressure operation of steam.
The advantage of using globe valve:
The advantage of using globe valve:
- Reliable shutoff capability
- Throttling capability
- Disc and Seat easy for repairing
- Fast operation due to shorter stroke length (compare to gate valve)
- Available in different Y, Z and angle types
- Easy to machine or resurface the seats
6. Gate valve vs globe valve
There is a difference between gate valve and globe valve.
There is a difference between gate valve and globe valve.
- Function: The gate valve is designed to start and stop the flow without any flow regulation purposes. It is used for isolation applications where frequent opening and closing is required. Globe valve is designed to the contrary and can be modulate and reduce the flow with precision or throttling purposes. They are majorly used in the control valve industry to obtain a flow that can be calculated in accuracy.
- Application: Gate valves are suitable for low pressure drop application and it is a multi-directional valve. Globe valves are suitable in application where massive changes in pressure are required.
- Installation: Gate Valve can be installed in various directions but globe valve can only flow in one direction and the direction arrow is embossed on the valve body.
- Sealing: Globe valves generally have seals which are better than gate valves.
Threaded End Forged Steel Globe Valve
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