How Globe Valve Works

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This article will provide an overall description of the globe valve, its design, and its applications. The globe valve owes its name to the spherical shape of its body. These valves are designed for start/stop services and are ideally suited for throttling services.

Design and Types of Globe Valve

Globe valves are linear motion valves used for on-off and throttling services to regulate fluid flow. These valves have structural elements similar to those in gate valves, as depicted in Figure 1.

Globe valve bodies are available in a wide range of materials, commonly including cast iron, cast steel, forged steel, and corrosion-resistant alloys. They also feature various body-end connections, such as screwed, flanged, and welded types.

The valve can feature different bonnet designs (union, screwed-in, flanged, pressure-sealed, etc.) and stem types (inside screw, outside screw, sliding stem). However, the most significant design differences are found in the disc (plug) design. Besides conventional discs, common designs include tapered plug discs and composite discs. Globe valve seats are either integral with or screwed into the valve body. Many globe valves have backseats to prevent system pressure from building against the valve packing when the valve is fully open.

Globe valves may close the disk against or in the same direction as the fluid flow. When the disk closes in the same direction as the flow, the kinetic energy of the fluid aids in closing but impedes opening, which is advantageous for quick-acting stop valves.

Body Designs

Concerning the valve body design, there are primarily three globe valve body types: Z-type, Y-type, and angled.

The Z-body design, shown in Figure 1, is the simplest and most common for water applications. The Y-body design, or cross-flow globe valve, reduces the inherent high pressure drop. The angle type, shown in Figure 3, features perpendicular inlet and outlet connections, facilitating flow transition from vertical to horizontal.

Operating Principle

In operation, the fluid flow through a globe valve follows a changing course. Fluid enters the valve parallel to the port, makes two 90-degree turns, then exits parallel to the port.

The valve seating, parallel to the flow line, allows the disk to be fully removed from the flow path when open or to completely close the flow path when shut. This gives the globe valve good throttling ability, making it useful for regulating flow.

Applications and Benefits

Globe valves are suitable for a wide range of industrial applications. A composition disc is ideal for tight seating with hard-to-hold fluids like gas and compressed air, although it is not recommended for throttling.

The tapered plug disk offers better throttling, thanks to its configuration providing wide seating contact that allows close regulation of flow.

The conventional disc design is ideal for the positive shut-off of liquids but is not recommended for throttling.

Angle body designs can serve as both a valve and a piping elbow, and they offer favorable discharge conditions concerning fluid dynamics and erosion.

The Y-design provides a pressure-resistant envelope for the stem, bonnet, and packing, making it suitable for high pressures and severe service conditions.

For steam applications, globe valves are often welded into the system, and their top-entry maintenance design makes them ideal for the power industry. The disc and seat can be easily replaced, which is advantageous for applications requiring frequent maintenance.

This article offers a brief introduction to globe valves. For further information or to address any questions about globe valves or other types of valves, please contact us via email at sales@wfecn.com or call +86 (577) 5775 5599.

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