ASME B16.5 - Dimensional Tolerances
WELDING NECK FLANGES
| Grade | Certificate | Plate thickness
in mm |
Wiidth in mm |
Length in mm | |
| O
|
Outside Diameter | When O is 24" or less. When O is over 24". | ±0.06" ±0.12" | ±1.6 mm | ±3.2 mm |
| R |
Diameter of Contact Face | 0.06" (1.6 mm) raised face. 0.25" (6.4 mm) raised face. | ±0.03" ±0.02" | ±0.8 mm | ±0.5mm |
| A | Diameter of Hub at Point of Welding | NPS 5 and smaller. NPS 6 and larger. | +0.09", -0.03" +0.16", -0.03" | +2.4 mm, -0.8mm | +4.0 mm, -0.8 mm |
| B | Inside Diameter | NPS 10, 12, 18, 20 and larger. | +0.03" +0.06" +0.12", -0.06" | +0.8 mm +1.6 mm | +3.2 mm, -1.6 mm |
| X | Diameter of Hub at Base | Hub Base is 24"or less. Hub Base is over 24". | +0.06" +0.12" | +1.6 mm | +3.2 mm |
| C | Thickness | NPS 18 and smaller. NPS 20 and larger. | +0.12" +0.19" | +3.2 mm | +4.8 mm |
| Drilling and Facings | Bolt circle diameter Bolt Hole Spacing | ±0.06" ±0.03" | ±1.6 mm | ±0.8 mm | |
| Eccentricity of Bolt Circle and Facing | NPS 2 1/2 and smaller. NPS 3 and larger. | ±0.03" ±0.06" | ±0.8 mm | ±1.6 mm | |
| Length Through Hub | NPS 10 and smaller. NPS 12 and larger. | ±0.06" ±0.12" | ±1.6 mm | ±3.2 mm | |
SLIP-ON, LAP JOINT, SOCKET WELDING AND THREADED FLANGES
| Grade | Certificate | Plate thickness in mm | Wiidth in mm |
Length in mm | |
| O
|
Outside Diameter | When O is 24" or less. When O is over 24". | ±0.06" ±0.12" | ±1.6 mm | ±3.2 mm |
| R |
Facings | 0.06" (1.6 mm) raised face. 0.25" (6.4 mm) raised face. | ±0.03" ±0.02" | ±0.8 mm | ±0.5mm |
| B |
Inside Diameter at face of Socket Welding Flanges | NPS 10 and smaller. NPS 12 to 18, inclusive. NPS 20 and larger. | ±0.03" ±0.06" +0.12", -0.06" | ±0.8 mm ±1.6 mm | +3.2 mm, -1.6 mm |
Q |
Counterbore, Threaded Flanges | NPS 10 and smaller NPS 12 and larger | +0.03" +0.06" | +0.8 mm | +1.6 mm |
| X | Diameter of Hub at Base | NPS 12" and smaller. NPS 14" and larger. | +0.09", -0.06" ±0.12" | +2.4 mm | -1.6 mm ±3.2 mm |
| C | Thickness | NPS 18 and smaller. NPS 20 and larger. | +0.12" +0.19" | +3.2 mm | +4.8 mm |
| Drilling | Bolt Circle Diameter Bolt Hole Spacing | ±0.06" ±0.03" | ±1.6 mm | ±0.8 mm | |
| Eccentricity of Bolt Circle and Facing | NPS 2 1/2 and smaller. NPS 3 and larger. | ±0.03" ±0.06" | ±0.8 mm | ±1.6 mm | |
| Length Through Hub | NPS 18 and smaller. NPS 20 and larger. | +0.12", -0.03" +0.19", -0.03" | +3.2 mm, -0.8 mm | +4.8 mm, -1.6 mm | |
Disclaimer: These dimensions are provided for reference material only.