ANSI B16.5 Class 1500 Welding Neck Flanges
| NPS | Outside Diameter (O) | Thickness (T) | Hub Diameter (X) | Neck Diameter (A) | Length Through Hub (Y) | Bore (B) | Diameter of Bolt Circle (C) | Diameter of Bolt Holes (in) | Number of Bolts |
|---|---|---|---|---|---|---|---|---|---|
| ½ | 121 | 22.4 | 38 | 21.3 | 60 | 15.7 | 82.6 | 7/8 | 4 |
| ¾ | 130 | 25.4 | 44 | 26.7 | 70 | 20.8 | 88.9 | 7/8 | 4 |
| 1 | 149 | 28.4 | 52 | 33.5 | 73 | 26.7 | 101.6 | 1 | 4 |
| 1¼ | 159 | 28.4 | 64 | 42.2 | 73 | 35.1 | 111.1 | 1 | 4 |
| 1½ | 178 | 31.8 | 70 | 48.3 | 83 | 40.9 | 124 | 1⅛ | 4 |
| 2 | 216 | 38.1 | 105 | 60.5 | 102 | 52.6 | 165.1 | 1 | 8 |
| 2½ | 244 | 41.1 | 124 | 73.2 | 105 | 62.7 | 190.5 | 1⅛ | 8 |
| 3 | 267 | 47.8 | 133 | 88.9 | 117 | 78 | 203.2 | 1¼ | 8 |
| 4 | 311 | 53.8 | 162 | 114.3 | 124 | 102.4 | 241.3 | 1¼ | 8 |
| 5 | 375 | 73.2 | 197 | 141.2 | 155 | 128.3 | 292.1 | 1⅜ | 8 |
| 6 | 394 | 82.6 | 229 | 168.4 | 171 | 154.2 | 317.5 | 1½ | 12 |
| 8 | 483 | 91.9 | 292 | 219.2 | 213 | 202.7 | 393.7 | 1¾ | 12 |
| 10 | 584 | 108 | 368 | 273 | 254 | 254.5 | 482.6 | 2 | 12 |
| 12 | 673 | 124 | 451 | 323.8 | 282 | 304.8 | 571.5 | 2-1/8″ | 16 |
| 14 | 749 | 133.4 | 495 | 355.6 | 298 | 336.54 | 635 | 2-3/8″ | 16 |
| 16 | 826 | 146 | 552 | 406.4 | 311 | 387.34 | 704.8 | 2-5/8″ | 16 |
| 18 | 914 | 162.1 | 597 | 457.2 | 327 | 437.94 | 774.7 | 2-7/8″ | 16 |
| 20 | 984 | 177.8 | 641 | 508 | 356 | 488.94 | 831.8 | 3-1/8″ | 16 |
| 24 | 1,168 | 203.2 | 762 | 609.6 | 406 | 590.94 | 990.6 | 3-5/8″ | 16 |