Cast Iron Flanges - ASME/ANSI Class 250
ASME/ANSI B16.1 Cast Iron Pipe Flanges and Flanged Fittings - Class 250 Flanges - outside and inside diameters, bolt circles, numbers and diameters of bolts.
ASME/ANSI B16.1 - 1998 - Cast Iron Pipe Flanges and Flanged Fittings - Class 250 Flanges - outside and inside diameters, bolt circles, numbers and diameters of bolts:
| Pipe Size (inches) | Outside Diameter (inches) | Number of Bolt Holes | Bolt Hole Diameter (inches) | Bolt Circle (inches) |
|---|---|---|---|---|
| 1 | 4-7/8 | 4 | 3/4 | 3-1/2 |
| 1-1/4 | 5-1/4 | 4 | 3/4 | 3-7/8 |
| 1-1/2 | 6-1/8 | 4 | 7/8 | 4-1/2 |
| 2 | 6-1/2 | 8 | 3/4 | 5 |
| 2-1/2 | 7-1/2 | 8 | 7/8 | 5-7/8 |
| 3 | 8-1/4 | 8 | 7/8 | 6-5/8 |
| 3-1/2 | 9 | 8 | 7/8 | 7-1/4 |
| 4 | 10 | 8 | 7/8 | 7-7/8 |
| 5 | 11 | 8 | 7/8 | 9-1/4 |
| 6 | 12-1/2 | 12 | 7/8 | 10-5/8 |
| 8 | 15 | 12 | 1 | 13 |
| 10 | 17-1/2 | 16 | 1-1/8 | 15-1/4 |
| 12 | 20-1/2 | 16 | 1-1/4 | 17-3/4 |
| 14 | 23 | 20 | 1-1/4 | 20-1/4 |
| 16 | 25-1/2 | 20 | 1-3/8 | 22-1/2 |
| 18 | 28 | 24 | 1-3/8 | 24-3/4 |
| 20 | 30-1/2 | 24 | 1-3/8 | 27 |
| 24 | 36 | 24 | 1-5/8 | 32 |
| 30 | 43 | 28 | 2 | 39-1/4 |
| 36 | 50 | 32 | 2-1/4 | 46 |
| 42 | 57 | 36 | 2-1/4 | 52-3/4 |
| 48 | 65 | 40 | 2-1/4 | 60-3/4 |
- 1 inch = 25.4 mm
