As a prevalent shut-off valve, globe valves play a vital role in industrial piping systems, building water supply/drainage, and fluid control fields. Their distinctive structure and performance characteristics secure their position among various valve types. This document elaborates on their structure, operating principle, performance features, and application scenarios.
I. Structure and Operating Principle
The closure element (disc) of a globe valve is driven by the stem to move linearly along the seat (sealing surface) axis, achieving valve opening/closing. Key components include:
Valve Body: Main housing connecting to pipelines.
Bonnet: Bolted/welded to the body for internal sealing.
Stem: Transmits torque from handwheel/actuator to the disc.
Disc: Typically disk/plug-shaped, mates with the seat for sealing.
Seating Surfaces: Precision-machined on disc/seat for leak-tight closure.
Stem Packing: Graphite/PTFE-filled gland prevents stem leakage.
Handwheel/Actuator: Manual/electric operation interface.
Operation:
Opening: Clockwise rotation raises the disc, unseating it to allow flow.
Closing: Counterclockwise rotation forces the disc downward to block flow.
This simple mechanism enables easy operation and automation compatibility.
II. Performance Characteristics
Superior Flow Regulation
Linear disc movement allows precise flow control via adjustable opening degrees, outperforming gate valves in throttling applications.
Moderate Sealing Performance
Friction between disc and seat during operation, coupled with material/processing limitations, results in lower sealing reliability under high-P/T or particulate-laden media compared to gate valves.
Simple Maintenance-Friendly Structure
Minimalist design (body, bonnet, stem, disc) reduces manufacturing costs and enables quick repairs via bonnet removal without specialized tools.
High Flow Resistance
S-shaped flow path creates significant pressure drop, making globe valves unsuitable for high-flow/high-pressure systems where energy efficiency is critical.
Cost-Effectiveness
Economical due to mature manufacturing processes, ideal for budget-sensitive small/medium-bore pipelines.
III. Application Scenarios
Globe valves are widely deployed in:
Oil & Gas: Flow control in refining/transmission systems.
Chemical Plants: Precise dosing of corrosive chemicals.
Power/Water Treatment: Feedwater and sludge flow regulation.
HVAC Systems: Domestic hot/cold water and steam control.
They excel in low-pressure, frequent-cycling, or moderate-sealing-requirement scenarios (e.g., reactor feed/discharge ports), but should be avoided in high-flow-resistance-sensitive systems.
Conclusion: While offering excellent regulation, simplicity, and affordability, globe valves have limitations in sealing and flow efficiency. Proper selection based on operational demands ensures optimal system performance.