ANSI B16.5 Class 900 Welding Neck Flanges
| Nominal Pipe Size | Outside Diameter (O) | Thickness (T) | Raised Face Diameter (R) | Length Thru Hub (Y) | Hub Diameter (X) | Bore (B) | Approximate Weight | Bolt Circle (C) | Number of Holes | Diameter of Holes |
|---|---|---|---|---|---|---|---|---|---|---|
| 1/2 | 4.75 mm | 0.88 mm | 1.38 mm | 2.38 mm | 1.50 mm | Specified by purchaser | 5 lb | 3.25 mm | 4 | 0.88 mm |
| 3/4 | 5.13 mm | 1.00 mm | 1.69 mm | 2.75 mm | 1.75 mm | Specified by purchaser | 6 lb | 3.50 mm | 4 | 0.88 mm |
| 1 | 5.88 mm | 1.13 mm | 2.00 mm | 2.88 mm | 2.06 mm | Specified by purchaser | 9 lb | 4.00 mm | 4 | 1.00 mm |
| 1 1/4 | 6.25 mm | 1.13 mm | 2.50 mm | 2.88 mm | 2.50 mm | Specified by purchaser | 10 lb | 4.38 mm | 4 | 1.00 mm |
| 1 1/2 | 7.00 mm | 1.25 mm | 2.88 mm | 3.25 mm | 2.75 mm | Specified by purchaser | 13 lb | 4.88 mm | 4 | 1.13 mm |
| 2 | 8.50 mm | 1.50 mm | 3.63 mm | 4.00 mm | 4.13 mm | Specified by purchaser | 25 lb | 6.50 mm | 8 | 1.00 mm |
| 2 1/2 | 9.63 mm | 1.63 mm | 4.13 mm | 4.06 mm | 4.88 mm | Specified by purchaser | 36 lb | 7.50 mm | 8 | 1.13 mm |
| 3 | 9.50 mm | 1.50 mm | 5.00 mm | 4.00 mm | 5.00 mm | Specified by purchaser | 31 lb | 7.50 mm | 8 | 1.00 mm |
| 4 | 11.50 mm | 1.75 mm | 6.19 mm | 4.50 mm | 6.25 mm | Specified by purchaser | 53 lb | 9.25 mm | 8 | 1.25 mm |
| 5 | 13.75 mm | 2.00 mm | 7.31 mm | 5.00 mm | 7.50 mm | Specified by purchaser | 86 lb | 11.00 mm | 8 | 1.38 mm |
| 6 | 15.00 mm | 2.19 mm | 8.50 mm | 5.50 mm | 9.25 mm | Specified by purchaser | 110 lb | 12.50 mm | 12 | 1.25 mm |
| 8 | 18.50 mm | 2.50 mm | 10.63 mm | 6.38 mm | 11.75 mm | Specified by purchaser | 175 lb | 15.50 mm | 12 | 1.50 mm |
| 10 | 21.50 mm | 2.75 mm | 12.75 mm | 7.25 mm | 14.50 mm | Specified by purchaser | 260 lb | 18.50 mm | 16 | 1.50 mm |
| 12 | 24.00 mm | 3.13 mm | 15.00 mm | 7.88 mm | 16.50 mm | Specified by purchaser | 325 lb | 21.00 mm | 20 | 1.50 mm |
| 14 | 25.25 mm | 3.38 mm | 16.25 mm | 8.38 mm | 17.75 mm | Specified by purchaser | 400 lb | 22.00 mm | 20 | 1.63 mm |
| 16 | 27.75 mm | 3.50 mm | 18.50 mm | 8.50 mm | 20.00 mm | Specified by purchaser | 495 lb | 24.25 mm | 20 | 1.75 mm |
| 18 | 31.00 mm | 4.00 mm | 21.00 mm | 9.00 mm | 22.25 mm | Specified by purchaser | 680 lb | 27.00 mm | 20 | 2.00 mm |
| 20 | 33.75 mm | 4.25 mm | 23.00 mm | 9.75 mm | 24.50 mm | Specified by purchaser | 830 lb | 29.50 mm | 20 | 2.13 mm |
| 24 | 41.00 mm | 5.50 mm | 27.25 mm | 11.50 mm | 29.50 mm | Specified by purchaser | 1500 lb | 35.50 mm | 20 | 2.63 mm |