ASME B16.5 Flange Dimensions: Complete Size Chart and Selection Guide
Introduction
Understanding ASME B16.5 flange dimensions is essential for engineers, procurement specialists, and piping contractors. This comprehensive guide provides detailed dimension tables, pressure class specifications, and practical selection criteria for pipe flanges ranging from 1/2 inch to 24 inch nominal pipe size.
ASME B16.5 Standard Overview
What Is ASME B16.5?
ASME B16.5 is the American National Standard that covers:
- Pipe flanges and flanged fittings
- NPS 1/2 through NPS 24
- Pressure classes 150, 300, 400, 600, 900, 1500, and 2500
- Materials including carbon steel, stainless steel, and alloy steel
Pressure Class Designations
| Class | Designation | Typical Application |
|---|---|---|
| 150 | Class 150 | Low pressure, general service |
| 300 | Class 300 | Medium pressure systems |
| 600 | Class 600 | High pressure pipelines |
| 900 | Class 900 | Critical process systems |
| 1500 | Class 1500 | Extreme pressure conditions |
| 2500 | Class 2500 | Maximum pressure ratings |
Class 150 Flange Dimensions
| NPS | OD (mm) | Bolt Circle (mm) | Bolt Holes | Bolt Size | Thickness (mm) |
|---|---|---|---|---|---|
| 1/2 inch | 89 | 60 | 4 | M12 | 11 |
| 1 inch | 108 | 79 | 4 | M12 | 14 |
| 2 inch | 152 | 121 | 4 | M16 | 16 |
| 4 inch | 229 | 191 | 8 | M16 | 19 |
| 6 inch | 279 | 241 | 8 | M20 | 21 |
| 8 inch | 343 | 298 | 8 | M20 | 24 |
| 12 inch | 483 | 432 | 12 | M24 | 25 |
| 24 inch | 813 | 749 | 20 | M36 | 37 |
Flange Face Types
Raised Face (RF)
- Most common configuration
- 1.6mm (1/16 inch) for Class 150-300
- 6.4mm (1/4 inch) for Class 400 and above
- Suitable for most gasket types
Ring Type Joint (RTJ)
- Metal-to-metal sealing
- High pressure applications
- Classes 600 and above
- Requires precision machining
Material Specifications
Carbon Steel Flanges:
- ASTM A105 – Forged carbon steel
- ASTM A350 LF2 – Low temperature service
- ASTM A694 – High strength carbon steel
Stainless Steel Flanges:
- ASTM A182 F304/F304L – General corrosion resistance
- ASTM A182 F316/F316L – Enhanced corrosion resistance
- ASTM A182 F321 – Stabilized for welding
Conclusion
Proper selection of ASME B16.5 flanges requires understanding of dimensions, pressure classes, materials, and application requirements.
Songhai Flanges supplies ASME B16.5 compliant flanges in all pressure classes, sizes, and materials with full certification and competitive pricing.
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