Flange Facing Types Explained
The flange facing (sealing surface) is critical for creating a leak-tight joint. Different facing types are designed for specific pressure ranges, temperatures, and sealing requirements.
Raised Face (RF)
Most Common Type
- Raised sealing surface (1.6mm or 6.4mm height)
- Concentric or spiral serrations for gasket grip
- Suitable for Class 150-2500
- Works with soft, semi-metallic, and metallic gaskets
- Applications: General service, oil and gas, chemical processing
Flat Face (FF)
Full Surface Sealing
- Entire flange face is sealing surface
- Requires full-face gasket
- Limited to Class 150 and Class 300
- Prevents flange bending under bolt load
- Applications: Low-pressure water, cast iron flanges, plastic-lined systems
Ring Type Joint (RTJ)
High Pressure Metal-to-Metal Seal
- Groove for metal ring gasket (oval or octagonal)
- Metal-to-metal contact for superior sealing
- Suitable for Class 600 and above
- Handles extreme temperatures and pressures
- Applications: High-pressure steam, oil and gas wellheads, refineries
Male-Female Face (MFM)
Self-Aligning Sealing
- One flange has raised male portion, other has recessed female
- Gasket sits in female recess for better alignment
- Reduced gasket blowout risk
- Applications: Pump and valve connections, heat exchangers
Tongue-Groove Face (TG)
Premium Sealing Performance
- Tongue on one flange fits into groove on mating flange
- Excellent gasket containment
- Superior sealing for hazardous media
- Higher cost due to precision machining
- Applications: Toxic gases, high-pressure hydraulic systems
Facing Selection Guide
| Facing Type | Pressure Range | Temperature | Cost |
|---|---|---|---|
| Flat Face (FF) | Low (Class 150-300) | Moderate | Low |
| Raised Face (RF) | Medium-High (Class 150-2500) | Wide | Medium |
| MFM | Medium-High | Wide | Medium-High |
| TG | High | Wide | High |
| RTJ | Very High (Class 600+) | Extreme | High |
Gasket Compatibility
- RF/FF: Non-asbestos, graphite, PTFE, spiral wound
- RTJ: Soft iron, stainless steel, Inconel ring gaskets
- MFM/TG: Sheet gaskets, spiral wound with centering ring
Choosing the correct flange facing type is essential for ensuring leak-free operation and optimal sealing performance in your piping system.
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