Globe Valves - Design and Application

Globe valves are one of the most prominent valve types utilised in industrial operations. Their name derives from the spherical form of their bodies, which are typically made of cast iron, steel, or other metals. Globe valves are designed to regulate the flow of fluid in a conduit system and are frequently employed in applications requiring precise control of the fluid flow rate.

Construction of Globe Valves

Valve bodies, bonnets, stems, discs, and seats are the main components that make up globe valves. The valve body is typically constructed from cast iron, steel, or other metals, and it contains the valve seat and disc. The bonnet contains the stem, which is connected to the disc and is affixed to the valve body. Typically, the stem of a valve is sealed with a packing chamber to prevent fluid leakage.

Operation of Globe Valves:

Globe valves control the passage of fluid through the valve body using a movable disc. When the valve is open, the disc is separated from the seat, permitting fluid to pass through the valve. When the valve is closed, the disc presses against the seat, preventing fluid transfer. Globe valves may be manually actuated with a handwheel or lever, or automatically with a pneumatic or electric actuator.

Applications of Globe Valves

Globe valves are frequently employed in applications requiring precise control of the fluid flow rate, such as in chemical and petrochemical plants, power generation facilities, and water treatment facilities. They are also utilised in steam applications, where the valve controls the steam's pressure and temperature. Globe valves can be used with liquids, gases, and steam, among other fluids.

Advantages of Globe Valves

Globe valves are superior to other forms of valves in several ways. They are designed for precision control of fluid flow rate, making them ideal for applications requiring precise fluid flow regulation. Additionally, they are simple to maintain and repair, as the valve body can be readily accessed for cleaning and part replacement. Moreover, globe valves can be utilised in both low- and high-pressure applications, making them versatile and applicable to a vast array of uses.

Disadvantages of Globe Valves

In comparison to other varieties of valves, such as gate valves, globe valves can be more expensive. On top of that, globe valves may be more challenging to operate in high-pressure applications, as the force required to move the disc against the seat increases with pressure.

Body Patterns of Globe Valves

 The body pattern of globe valves is an essential characteristic. The body pattern of a globe valve refers to the geometry, orientation, and associated connections of the valve body. Let's discuss the various body patterns and applications of globe valves.

Angle Pattern Globe Valves

Angle pattern globe valves have inlet and exhaust ports that are angled relative to one another. Typically, the inlet is at a right angle to the outflow. This design permits the valve to be affixed in any orientation and facilitates installation in tight spaces. Angle pattern globe valves are commonly used in applications with limited space and high-pressure drop requirements. These valves are typically used in steam, water, and gas applications.

Y-Pattern Globe Valves

The body shape of Y-pattern globe valves resembles the letter Y. The inlet and exhaust of these valves are in a straight line, while the flow path through the valve is at an angle to the valve body. This design minimises erosion of the valve seat and reduces pressure loss across the valve. In applications involving high-pressure drops, such as boiler feedwater systems, high-pressure steam lines, and oil and gas conduits, Y-pattern globe valves are commonly used.

Straight Design Globe Valves

Straight pattern globe valves have inlet and exhaust ports that are aligned in a straight line. The valve's passage path is perpendicular to the valve body. In applications involving low-pressure drops, such as in cooling water systems, air conditioning systems, and oil and gas conduits, these valves are frequently employed.

Cross-Design Globe Valves

The inlet and exhaust of cross pattern globe valves are perpendicular to one another. The flow path via the valve is at an angle to the body of the valve, which can result in a significant pressure decrease. Typically, these valves are used in applications where space is limited and high-pressure reductions are required, such as steam and gas applications.

Globe Valves with Bellows

Flexible bellows elements are welded to the stem and bonnet of bellows-sealed globe valves. The bellows element provides a leak-proof seal, making these valves ideal for use with hazardous or harmful fluids. These valves are commonly used in industries where product purity is crucial, such as chemical processing, pharmaceuticals, and others.

The body pattern of a globe valve is crucial to its performance and application. Depending on the specific requirements of the application, globe valves with various body styles offer distinct advantages and disadvantages. Engineers and designers can select the appropriate globe valve for their application to ensure dependable and efficient fluid flow control by understanding the numerous body patterns of globe valves.