Globe Valves

A globe valve, different from ball valve, is a type of valve used for regulating flow in a pipeline, consisting of a movable disk-type element and a stationary ring seat in a generally spherical body.

Description

Globe valve-Carbon

Globe valves are different from a ball valve and are a type of valve used for regulating flow in a pipeline, consisting of a movable disk-type element and a stationary ring seat in a generally spherical body.

Although globe valve-Carbon in the past had spherical bodies which gave them their name, many modern globe valves do not have much of a spherical shape. ย However, the term globe valve is still often used for valves that have such an internal mechanism. ย In plumbing, valves with such a mechanism are also often called stop valves since they don’t have spherical housing, but the term stop valve may refer to valves that are used to stop flow even when they have other mechanisms or designs.

Globe Valves

The body is the main pressure-containing structure of the valve and the most easily identified as it forms the mass of the valve. ย It contains all of the valve’s internal parts that will come in contact with the substance being controlled by the valve.

The bonnet is connected to the body and provides the containment of the fluid, gas, or slurry that is being controlled.

Globe valves are typically two-port valves, although three-port valves are also produced mostly in straight-flow configuration.ย  Ports are openings in the body for fluid flowing in or out. ย The two ports may be oriented straight across from each other or anywhere on the body, or oriented at an angle (such as a 90ยฐ).ย  Globe valves with ports at such an angle are called angle globe valves.

Globe valves are mainly used for corrosive or highly viscous fluids that solidify at room temperature.ย  This is because straight valves are designed so that the outlet pipe is in line with the inlet pipe and the fluid has a good chance of staying there in the case of horizontal piping.ย  In the case of angle valves, the outlet pipe is directed towards the bottom.

This allows the fluid to drain off. In turn, this prevents clogging and/or corrosion of the valve components over some time. A globe valve can also have a body in the shape of a “Y”.ย  This will allow the construction of the valve to be straight at the bottom.

Otherwise opposed to the conventional pot type construction (to arrange bottom seat) in case of other valves.ย  This will again allow the fluid to pass through without difficulty and minimize fluid clogging/corrosion in the long term.

Bonnet

The bonnet provides a leakproof closure for the valve body. The threaded section of the stem goes through a hole with matching threads in the bonnet.

Globe valves may have a screw-in, union, or bolted bonnet.ย  Screw-in bonnet is the simplest bonnet, offering a durable, pressure-tight seal.ย  Union bonnet is suitable for applications requiring frequent inspection or cleaning.ย  It also gives the body added strength.

A bonnet attached with bolts is used for larger or higher-pressure applications.ย  The bonnet also contains the packing, a wearable material that maintains the seal between the bonnet and the stem during valve cycling.

Plug or Disc (Disk)

The closure member of the valve, plugs is connected to the stem which is slid or screwed up or down to throttle the flow. ย Plugs are typically of the balanced or unbalanced type.

Unbalanced plugs are solid and are used with smaller valves or with low-pressure drops across the valve. ย The advantages are simpler design, with one possible leak path at the seat, and usually lower cost. The disadvantage is the limited size; with a large unbalanced plug, the forces needed to seat and hold the flow often become impractical. Balanced plugs have holes through the plug.

Advantages include easier shut-off as the plug does not have to overcome static forces. However, a second leak path is created between the plug and the cage, and the cost is generally higher.

Stem

The stem serves as a connector from the actuator to the inside of the valve and transmits this actuation force. ย Stems are either smooth for actuator-controlled valves or threaded for manual valves.

The smooth stems are surrounded by packing material to prevent leaking material from the valve. ย This packing is a wearable material and will have to be replaced during maintenance. ย With a smooth stem, the ends are threaded to allow connection to the plug and the actuator.

The stem must not only withstand a large amount of compression force during valve closure.ย  It will also have high strength on valve opening.ย  In addition, the stem must be very straight, or have low run out, to ensure good valve closure. ย This minimum run out also minimizes wear of the packing contained in the bonnet, which provides the seal against leakage.

The stem may be provided with a shroud over the packing nut to prevent foreign bodies from entering the packing material.ย  This foreign body would accelerate wear.

Cage

The cage is a part of the valve that surrounds the plug and is located inside the body of the valve. ย Typically, the cage is one of the greatest determiners of flow within the valve. ย As the plug is moved more of the openings in the cage are exposed and flow is increased and vice versa.

The design and layout of the openings can have a large effect on the flow of material.ย  Cages are also used to guide the plug to the seat of the valve for a good shutoff, substituting the guiding from the bonnet.

Seat

The seat ring provides a stable, uniform, and replaceable shut-off surface.ย  Seats are usually screwed in or torqued. ย This pushes the cage down on the lip of the seat and holds it firmly to the body of the valve.ย  Seat may also be threaded and screwed into a thread cut in the same area of the body.

However, this method makes the removal of the seat ring during maintenance difficult if not impossible. ย Seat rings are also typically beveled at the seating surface.ย  It allows for some guidance during the final stages of closing the valve.

Economical globe valves or stop valves with a similar mechanism used in plumbing often have a rubber washer at the bottom of the disc for the seating surface.ย  This is so that rubber can be compressed against the seat to form a leak-tight seal when shut.

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Type of Globe Valves

Butterfly Valves

Ball Valves

Additional information

Weight 25 lbs
Dimensions 24 × 12 × 12 in
Size

1/2", 3/4", 1", 1-1/2", 2", 3", 4", 6", 8", 12"

Connection Ends

Threaded (FNPT), Flanged (Class150), Socket, Sanitary (Tri Clamp)

Materials of Construction

Bronze, Cast Iron, Carbon Steel, Stainless Steel

Seal Type

TEFC (Default), Graphite (High Pressure / High Temperature), Metal (High Pressure / High Temperature)

Class

150LB (Default), 300LB, 600LB

Temperature

400F (Default), 800F

Specifications

Globe Valve Specifications

Globe Valve Flange End

 

 

Q&A

Q:ย  What is a globe valve?

A:ย  A globe valve is a type of valve used to regulate flow in a pipeline. It consists of a movable disk (or plug) and a stationary ring seat.

Q:ย  What are the common applications of globe valves?

A:ย  Globe valves are commonly used in cooling water systems, fuel oil systems, boiler feedwater systems, and other applications that require throttling or isolation.

Q:ย  How does a globe valve differ from other types of valves?

A:ย  Unlike gate valves that provide full flow or block flow completely, globe valves are designed to regulate flow by adjusting the position of the disk in relation to the seat.

Q:ย  What are the advantages of using globe valves?

A:ย  Globe valves offer good throttling ability, precise flow control, and can be used in moderate to high-pressure applications. They also provide a tight seal when closed.

Q:ย  What are the main components of a globe valve?

A:ย  The main components of a globe valve include the body, bonnet, disk (or plug), stem, seat, and handwheel or actuator for operation.

Q:ย  How do you maintain a globe valve?

A:ย  Maintenance of globe valves typically involves regular inspection for leaks, cleaning or replacing damaged parts, lubricating moving components, and ensuring proper alignment of the valve.

Feel free to ask more specific questions if you have any!

Advantages / Disadvantages

Advantages of Globe Valves

Precise Flow Control:ย  Globe valves offer excellent throttling capability, allowing for precise adjustment of flow rate.

Good Shut-Off Capability:ย  When fully closed, globe valves provide a tight seal, minimizing leakage.

Versatility:ย  Globe valves can be used in a wide range of applications, including high-pressure and high-temperature environments.

Durability:ย  These valves are typically robust and long-lasting, making them suitable for various industrial settings.

Easy Maintenance:ย  Globe valves are relatively easy to maintain and repair, with straightforward access to internal components.

Disadvantages of Globe Valves

Pressure Drop:ย  Globe valves can cause pressure loss due to their design, which can impact system efficiency.

Slower Operation:ย  Compared to some other valve types, such as gate valves, globe valves may have slower opening and closing times.

Higher Cost:ย  Globe valves can be more expensive than some other valve types, which can be a drawback for budget-conscious projects.

Complexity:ย  Globe valves consist of multiple components that may require more intricate maintenance procedures compared to simpler valve designs.

Limited Flow Capacity:ย  In fully open position, globe valves may have restrictions that limit their flow capacity compared to some other valve types like ball valves.

These advantages and disadvantages should be considered when selecting globe valves for specific applications. Let me know if you need more information!

Applications

Globe valves are versatile and find applications in various industries due to their ability to regulate flow.ย  Here are some common applications for globe valves:

Boiler Feedwater Systems:ย  Globe valves are commonly used in boiler feedwater systems to control the flow of water into the boiler.ย  They help maintain the desired water level and pressure within the boiler system.

Cooling Water Systems:ย  Globe valves are used in cooling water systems to regulate the flow of water through heat exchangers, condensers, and other components.ย  They help in maintaining the temperature of industrial processes.

HVAC Systems:ย  In heating, ventilation, and air conditioning (HVAC) systems, globe valves play a crucial role in controlling the flow of water or steam to regulate the temperature in buildings.

Steam Systems:ย  Globe valves are employed in steam systems to control the flow of steam in pipelines, ensuring efficient operation and safety.

Process Control Industries:ย  Globe valves are used in various process industries such as chemical, petrochemical, and pharmaceutical industries for precise flow control of liquids, gases, and steam.

Water Treatment Plants:ย  Globe valves are utilized in water treatment plants to regulate the flow of water during different treatment processes like filtration, chlorination, and disinfection.

Oil and Gas Industry:ย  Globe valves are found in oil and gas pipelines and refineries for controlling the flow of oil, gas, and other fluids in different stages of the production and transportation process.

Power Plants:ย  Globe valves play a significant role in power plants for controlling the flow of water, steam, and other fluids in various systems like turbines, condensers, and generator cooling systems.

Mining Industry:ย  Globe valves are used in mining operations to regulate the flow of water, acids, and other liquids in processing and extraction systems.

Marine Applications:ย  Globe valves are employed in marine systems for controlling the flow of seawater, fuel, and other fluids in onboard systems like cooling, ballasting, and fuel systems.

These are just a few examples of the diverse applications where globe valves are utilized for efficient flow control and system operation.ย  Let me know if you need more information on any specific application!

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