Quick Answer
A globe valve diagram shows the key parts: handwheel, stem, bonnet, body, disc, seat, and the S-shaped flow path. The valve throttles flow by moving a disc toward a seat; media flows in one side, turns, and exits the other, which gives good control but higher pressure drop than a gate or ball valve. The P&ID symbol is a circle with a vertical line and a small tee-like stem.
Main Parts of a Globe Valve
| Part | Function |
|---|---|
| Handwheel / actuator | Moves the stem linearly |
| Stem | Transfers force to the disc |
| Bonnet | Seals the body top |
| Disc / plug | Closing element, throttles flow |
| Seat ring | Sealing surface |
| Body | S-shaped flow passage |
Flow Path and Orientation
Media enters below the seat and exits above in most globe valves (flow under the seat), which keeps the packing away from line pressure when closed. The change in direction is what creates the characteristic pressure drop of a globe valve — about 5-10 times that of a gate valve in comparable service.
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Globe Valve Symbol in P&ID
The globe valve symbol is a circle with a vertical stem line above, and a horizontal line across the middle of the circle (like a small table). Like all valve symbols, confirm with the tag and data sheet.
Troubleshooting Checklist for Globe Valves
- Leakage past a closed globe valve: inspect and lap the seat, check disc wear
- Stem leak: tighten or replace gland packing
- Hard to turn: clean and lubricate stem threads; check for galling
- Noise / vibration in throttling: check for cavitation; adjust opening or trim
- Always isolate and depressurize before maintenance
Frequently Asked Questions
Why does a globe valve have higher pressure drop than a gate valve?
The S-shaped flow path forces the media to change direction, creating turbulence and resistance. That is the price of precise throttling control.
Which direction should a globe valve be installed?
Most globe valves are installed with flow entering below the seat (arrow on the body). Follow the cast arrow — wrong orientation can damage the disc and packing.
What is a globe valve used for?
Throttling and control: flow regulation, bypass lines, and services where tight shut-off with adjustable flow is needed.
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Disclaimer: This article is provided for general educational and informational purposes only and does not constitute professional engineering advice. Valve applications vary with pressure, temperature, media, and applicable codes. Always verify specifications against the manufacturer’s data sheet and consult a qualified engineer before selecting, installing, or repairing any valve. Valve Knowledge Hub makes no warranties about the accuracy or completeness of the information on this site and assumes no liability for any use of it.