Advantages and disadvantages of globe valve

Definition of Globe Valve

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A globe valve is a type of valve where the closing mechanism (valve disc) moves linearly along the axis of the valve seat. This design allows for effective flow regulation through the valve.

Typically, a globe valve consists of major components such as a handwheel, valve stem, valve body, valve cover, and valve flap (closure). The handwheel connects to the valve stem, enabling the valve flap to make linear movements along the valve seat axis, thereby controlling the flow through the pipeline.

These valves are mainly utilized in high-pressure, small-diameter applications, often produced up to DN400 (NPS 16). Larger sizes are reserved for special applications, such as large oxygen pipelines, where other valve types could pose a fire hazard due to friction.

Working Principle of Globe Valves

In a globe valve, the stem typically performs a rotary lifting motion, with a handwheel fixed at the top of the stem. When the handwheel rotates clockwise, the stem descends, bringing the sealing surfaces into contact and the valve closes. Conversely, rotating counterclockwise will lift the stem, disengaging the sealing surfaces and opening the valve.

Advantages of Globe Valves:

#1 Compared to gate valves, globe valves feature a simpler structure with typically one sealing surface on both the valve body and disc. This compact design saves material and cost while facilitating smoother manufacturing and maintenance.

#2 Minimal wear and tear: The sealing surfaces experience limited wear since there is no significant sliding between the valve disc and body when being opened or closed, resulting in good sealing performance and extended longevity.

#3 Space efficiency: The required opening height is usually only about one-fourth of the valve seat’s diameter, making them compact and installation-friendly.

#4 Precise control: Globe valves allow for precise fluid flow regulation. They can be finely adjusted to deliver various flow rates, making them suitable for diverse industrial applications.

#5 High-pressure capability: Their unique design allows globe valves to manage high-pressure settings effectively, ensuring stability in systems where pressure is a key concern.

#6 Efficient shutoff: Globe valves offer reliable shutoff capabilities, effectively preventing fluid flow in both directions, which is vital in many applications.

#7 Versatility: Capable of handling gases, liquids, and slurries, globe valves serve a wide variety of industries such as petrochemical, manufacturing, refining, and water treatment.

#8 Durability: With proper maintenance, globe valves have a long lifespan and are resistant to leakage, which helps in avoiding equipment damage and reducing operational costs.

Disadvantages of Globe Valves:

#1 Pressure drop: A significant drawback of globe valves is the considerable pressure drop across them when fully open, which may lead to inefficiencies within the system and necessitate additional energy for maintaining flow rates.

#2 Size and weight: Generally, globe valves are bulkier and heavier compared to other valve types, complicating installation and increasing support structure requirements.

#3 Higher cost: The complexity of manufacturing and installation makes globe valves often more expensive compared to simpler valve designs.

#4 Maintenance needs: The presence of multiple internal components can result in frequent maintenance requirements, as these parts may wear down or get damaged over time.

#5 Limited high flow applications: In high flow scenarios, globe valves can experience cavitation and erosion, restricting their effectiveness.

Classification of Globe Valves:

#1 By Design: Globe valves can be categorized into different designs including T-pattern, Y-pattern, and angle pattern, each offering distinct advantages for flow control and pressure drops.

#2 By Body Material: Various materials such as stainless steel, carbon steel, and cast iron are used for globe valves, selected based on fluid type, pressure, temperature, and necessary durability.

#3 By Stem Type: Classification can also occur based on the stem type: rising stem, non-rising stem, or rotary stem, which dictate how the valve opens and closes.

#4 By Number of Ports: Globe valves can be single-port or double-port, where single-port valves have one inlet and one outlet while double-port designs may accommodate multiple ports for complex flow configurations.

#5 By Operating Mechanism: These valves can be manually operated or powered by electric, pneumatic, hydraulic, or solenoid mechanisms depending on specific application needs.

Applicable Conditions for Globe Valves:

#1 High-pressure environments: Ideal for systems with high-pressure requirements to prevent fluid escape.

#2 Flow regulation: Perfect for processes that demand precise flow rate control.

#3 High-temperature settings: Behave reliably under extreme temperatures where other valves may fail.

#4 Corrosive substances: Their construction enables the handling of corrosive and abrasive fluids safely.

#5 Liquid operations: Commonly used in liquid applications like those in treatment plants or chemical facilities.

#6 Process monitoring: Effective for maintaining critical process conditions such as pressure and temperature.

#7 Viscous fluids: Capable of managing high-viscosity fluids with great precision.

Overall, globe valves excel in applications requiring precise control, effective shutoff capabilities, and adaptable flow rates, ensuring reliable management of pressure and temperature within piping systems.