Gate Valve Vs. Globe Valve: In-depth - Plumberstar

What is a Gate Valve?

A gate valve is a type of control valve that offers an unobstructed path for media flow or halts the fluid flow entirely. The main advantage of a gate valve lies in its full port design which ensures minimal pressure loss. Unlike a butterfly valve, the gate valve’s open bore design aids in cleaning processes. However, because they operate slower than quarter-turn valves, gate valves are best used in either a fully open or fully closed position. While automated gate valves with electric or pneumatic actuators exist, manual gate valves are more cost-effective. Commonly referred to as sluice gate valves, they are prominent in various applications. For more details, visit globe valve gate valve difference.

What is a Globe Valve?

Globe valves regulate fluid flow in conduits through linear motion. Incorporated within a spherical body, they use a movable disk or plug mechanism to manage fluid flow by either closing, opening, or partially obstructing the valve’s pathway.

Gate Valve Vs. Globe Valve: In-depth Guide

1) Gate Valve Vs. Globe Valve: Design

• Gate Valve Design

The gate valve's straightforward design makes it versatile for multiple low-pressure applications. Its full-port construction ensures that the valve's outlet matches the internal diameter of the connecting pipe, causing minimal impact on fluid flow with negligible pressure drop.

• Globe Valve Design

Globe valves come in diverse shapes and design variations but serve the same primary function of fluid flow regulation. Each design can impact the flow path and subsequent head loss.

• T- or Z-globe valve

The T-shaped or Z-shaped globe valve is the most prevalent. Despite the T-pattern description, a Z-shaped flow path better describes the fluid movement within the valve, leading to substantial head loss.

• Angle globe valve

Angle globe valves feature a 90-degree angle between the inlet and outlet, combining the functions of a pipe elbow and a valve. This design reduces head loss by limiting fluid direction changes.

• Y-globe valve

The Y-pattern globe valve offers an alternative to the T-pattern, with an angled bonnet and stem relative to the valve body, yielding a Y-pattern flow path. This configuration reduces head loss by making the flow path more direct.

Gate Valve Vs. Globe Valve: Components

• Gate Valve Components

Key components of a gate valve include the handwheel, stem, gasket, bonnet, valve body, flange, and gate. These parts may feature design variations based on specific applications, but their fundamental purpose remains consistent.

• Globe Valve Components

Core components of a globe valve include:

• Body: Typically constructed from materials like cast iron, carbon steel, stainless steel, or alloys.
• Bonnet: Houses the stem and packing at the valve's top.
• Stem: A threaded rod that raises or lowers the disk or plug.
• Disk or Plug: Movable components that manage flow by obstructing the flow path.
• Seat: A static part, against which the disk or plug seals to stop flow.
• Handwheel or Actuator: Mechanisms to manually or automatically operate the valve.

Gate Valve Working

Gate valves operate similarly to other valves. Turning the handwheel raises or lowers the gate through the threads on the stem, requiring multiple 360-degree rotations for full operation. When lifted, the gate reveals an unobstructed passage from the inlet to the outlet, allowing fluid flow. Conversely, lowering the gate halts the flow. The gate’s vertical travel and flow rate relationship are nonlinear, with substantial changes near full closure. Using gate valves for flow regulation can shorten their lifespan due to potential wear and vibrations. Hence, they are best suited for on/off control.

Globe Valve Working

Globe valve operation requires more than 360-degree handwheel turns for full cycling. Key parts include the valve body, bonnet, handwheel, stem, and plug. Media flows in through an inlet and exits via an outlet, with the bonnet covering the threaded components. Rotating the handwheel adjusts the threaded stem, raising or lowering the plug to open or close the valve. Thus, the flow rate is modulated proportionally to the plug’s position.

Gate Valve Vs. Globe Valve: Flow Properties

Gate valves permit bidirectional, straight-through flow, changing only when the valve closes. In contrast, globe valves have complex flow paths that can follow z-patterns, Y-patterns, or 90-degree turns, causing more significant pressure drops.

Gate Valve Vs. Globe Valve: Valve Functions

While globe valves can restrict flow, gate valves cannot. Globe valves' internal design enables efficient regulation, but they become less suitable for larger diameters. Both valves can be manually, pneumatically, or electrically operated.

Gate Valve Vs. Globe Valve: Sealing Surface

Gate valves' sealing surfaces frequently contact each other during operation, leading to wear. Globe valve seats and sealing surfaces, however, only touch when shut, reducing wear. Solid particles can still damage globe valve surfaces. Self-sealing occurs in gate valves, as media pressure tightens the seal.

Gate Valve Vs. Globe Valve: Drops in Pressure

Fully opened gate valves result in minimal pressure drops, while globe valves inherently cause significant pressure drops due to their S-shaped passages.

Gate Valve Material

Gate valves handle various media, necessitating careful material selection to avoid premature failure. Consider media composition, material compatibility, exposure duration, operating pressure, service temperatures, coating efficiency, availability, and cost.

Gate valve body materials

• Brass gate valve: An alternative to PVC in more demanding conditions.

Brass valves withstand temperatures between -20 °C and 120 °C and pressures from 0 to 16 bar. They are costlier than PVC but cheaper than stainless steel gate valves and are ideal for high-temperature residential piping and industries using natural gas or potable water.

Stainless steel gate valve

Stainless steel offers superior durability, heat, and corrosion resistance compared to brass and PVC, making it appropriate for a wide array of temperatures and pressures. These valves are employed in liquid, gas, and steam applications and generally feature simpler designs, facilitating easier maintenance and repair but are more expensive.

Common applications include marine and industrial sectors, transporting natural gas, crude oil, and slurry.

Bronze gate valve

• Bronze gate valve features: Excellent machinability, tensile strength, and corrosion resistance, suitable for low-pressure applications, and generally used for water pipes and equipment conduits operating at pressures up to 300 psi and temperatures between -20 °C and 150 °C. Bronze is costlier than PVC but cheaper than brass and stainless steel.

Unfortunately, due to its higher lead content, bronze is not commonly used for drinking water. Instead, it is popular for low-pressure manufacturing industries, HVAC, and marine applications.

Globe Valve Material

Globe valve bodies commonly use cast iron or brass/bronze for low-pressure settings and forged carbon steel or stainless steel for higher pressures and temperatures. Sizing a globe valve can be more complex due to potential pressure loss, often requiring ASME class pressure ratings and standard flange connections.

Gate valve applications

Gate valves are versatile in both industrial and residential settings for applications such as:

• Slurries: Facilitates slurry passage with an unobstructed path, helpful in sediment-heavy environments.
• Water gate valves: Suitable for non-flow control water applications, offering full open or closed regulation.

Applications of Globe Valve

Globe valves excel in industrial processes where flow control is necessary. Their robust closing mechanism ensures airtight seals in high-point vents and low-point drainage systems, valuable in systems like cooling, chemical feeding, feed water, and turbine lube systems, among others.

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These valves are optimal for addressing leakage in residential and commercial settings.

Gate Valve Vs. Globe Valve: Working Temperature and Pressure

Both valves come in materials like brass, stainless steel, and bronze, each suitable for different temperatures. Bronze gate valves typically operate within -10°C to 120°C and up to 16 bar pressure, while brass globe valves work between -30°C and 120°C at the same pressure.

Gate valve size:

Size: Pressure:

• 1/2” (DN 15), 16bar/232psi
• 3/4” (DN 20), 16bar/232psi
• 1” (DN 25), 16bar/232psi
• 1 1/4” (DN 32), 16bar/232psi
• 1 1/2” (DN 40), 16bar/232psi
• 2” (DN 50), 16bar/232psi
• 2 1/2” (DN 65), 16bar/232psi
• 3” (DN 80), 16bar/232psi

Globe valve size:

• DN Sizes (Inch), L, H
• 5 1/2”, 62, 101
• 20 3/4”, 74, 115
• 25 1”, 90, 125
• 32 1 1/4”, 100, 150
• 40 1 1/2”, 115, 159

Choosing Between Gate Valve and Globe Valve

When deciding between globe and gate valves, your specific needs determine the best choice:

• Flow Regulation: Select a globe valve for varying flow needs.
• Flow Capacity: Opt for a gate valve for high flow capacities.
• Flow Direction: Gate valves allow bidirectional flow.
• Sealing Needs: Globe valves provide superior sealing performance.
• Pressure Drop: Gate valves minimize pressure drops.
• Contaminated Media: Favor gate valves for slurry or contaminated media applications.

Globe Valve Vs. Gate Valve: Which is Better?

When comparing the two, globe valves offer superior durability and sealing, while gate valves have lower pressure drops. Gate valves are ideal for bidirectional flow needs, and globe valves excel in precise flow control scenarios.

What Issues Did We Resolve in This Article?

This guide clarifies the differences between gate and globe valves. Globe valves are best for flow regulation, while gate valves suit on/off applications. While globe valves are more complex and costly, they deliver superior performance. The application’s specific requirements should guide your choice.

Globe vs. Gate Valves: What's the Difference?