Globe Valve – Introduction
Globe Valve – Introduction
1. What is a Globe Valve?
O globe valve is a linear-motion valve designed for throttling flow and shut-off applications. Unlike gate valves (which are primarily for on/off service), globe valves provide precise flow control while also offering tight sealing when closed.
Key Characteristics:
✔ Flow Regulation: Excellent for adjusting flow rates.
✔ Good Shut-Off: Provides reliable sealing (less leakage than gate valves).
✔ Higher Pressure Drop: Due to the S-shaped flow path.
✔ Versatile Designs: Available in angle, T-type, and Y-pattern configurations.
2. Globe Valve Components
| Component | Funcţie |
|---|---|
| Corp | Houses internal parts; comes in T, Y, or angle patterns. |
| Bonnet | Covers the valve body; can be bolted, screwed, or welded. |
| Tulpina | Connects the handwheel to the disc for linear movement. |
| Disc (Plug) | Moves up/down to regulate flow (often tapered for tight shut-off). |
| Scaun | The sealing surface where the disc contacts to stop flow. |
| Handwheel / Actuator | Manual or automated control (electric, pneumatic). |
3. How Does a Globe Valve Work?
When open: Fluid flows in an S-path, passing around the disc.
When throttled: The disc partially obstructs flow, allowing precise control.
When closed: The disc presses firmly against the seat, preventing leakage.
Avantaje:
✅ Precise flow control (ideal for throttling).
✅ Better sealing than gate valves.
✅ Available in multiple designs (T, Y, angle).
✅ Handles high-pressure applications well.
Dezavantaje:
❌ Higher pressure drop than gate/ball valves.
❌ Heavier and bulkier than butterfly valves.
❌ Not ideal for slurries (can cause seat erosion).
4. Types of Globe Valves
| Type | Descriere | Best For |
|---|---|---|
| T-Pattern (Standard Globe Valve) | Z-shaped flow path, high pressure drop. | General throttling, steam, water. |
| Y-Pattern Globe Valve | Angled seat reduces pressure drop. | High-pressure systems, oil & gas. |
| Supapă cu glob unghiular | 90° turn in flow path, reduces turbulence. | Frequent start/stop applications, piping turns. |
| Bellows Seal Globe Valve | Leak-proof stem seal for hazardous fluids. | Toxic or radioactive media. |
| Pressure Seal Globe Valve | Improves sealing under high pressure. | Power plants, boiler systems. |
5. Applications of Globe Valves
Steam Systems (power plants, boilers)
Cooling Water Systems
Fuel Oil Systems
Prelucrare chimică (corrosion-resistant materials)
HVAC Systems (flow regulation)
Hydraulic Systems
6. Globe Valve vs. Gate Valve
| Caracteristică | Valvă globulară | Supapă de poartă |
|---|---|---|
| Funcţie | Throttling + Shut-off | On/Off only |
| Flow Path | S-shaped (higher pressure drop) | Straight (low pressure drop) |
| Sigilare | Better shut-off | May leak over time |
| Cost | More expensive | Cheaper |
| Întreţinere | Easier to repair | Harder to service |
7. Key Standards for Globe Valves
API 602 – Compact forged steel globe valves.
ASME B16.34 – Pressure-temperature ratings.
ANSI B16.10 – Face-to-face dimensions.
MSS SP-80 – Bronze globe valves.
ISO 17292 – Metal ball/globe valves.
Operators for Globe Valves
Most operators use the following guidelines to select the type of operators for Globe valves. When the effort to operate the lever exceeds 350 N geared operators are provided.
| Operator | Dimensiune | Rating |
|---|---|---|
| Handwheel | 10-inch and below | Class 150 |
| Handwheel | 8-inch and below | Class 300 |
| Handwheel | 4-inch and below | Class 600 |
| Handwheel | 3-inch and below | Class 900 |
| Handwheel | 2-inch and below | Class 1500 and 2500 |
| Gear Operator | 12-inch and above | Class 150 |
| Gear Operator | 10-inch and above | Class 300 |
| Gear Operator | 6-inch and above | Class 600 |
| Gear Operator | 4-inch and above | Class 900 |
| Gear Operator | 3-inch and above | Class 1500 and 2500 |
Concluzie
Globe valves are essential for flow control in systems requiring precise regulation and reliable sealing. While they introduce a higher pressure drop, their throttling capability makes them indispensable in industries like power generation, oil & gas, and chemical processing.
Need help selecting the right globe valve for your application? Let me know your system requirements! 🛠️
