Pipe flange is a method of connecting pipes, valves, pumps and other equipment to form a piping system. It also provides easy access for cleaning, inspection or modification.
| Nominal Pip Size | Outside Diameter of Flange | Diameter of Raised Face | Thickness of Flanges Min. | Diameter of Bolt Circle | Diameter of Bolt Holes | Number of Bolts | Approximate Weight kgs |
| NPS | O | R | tf | W | I | n | |
| 1/2 | 95 | 34.9 | 14.3 | 66.7 | 15.9 | 4 | 0.76 |
| 3/4 | 115 | 42.9 | 15.9 | 82.6 | 19.1 | 4 | 1.23 |
| 1 | 125 | 50.8 | 17.5 | 88.9 | 19.1 | 4 | 1.64 |
| 1 1/4 | 135 | 63.5 | 20.7 | 98.4 | 19.1 | 4 | 2.32 |
| 1 1/2 | 155 | 73.0 | 22.3 | 114.3 | 22.2 | 4 | 3.26 |
| 2 | 165 | 92.1 | 25.4 | 127.0 | 19.1 | 8 | 4.18 |
| 2 1/2 | 190 | 104.8 | 28.6 | 149.2 | 22.2 | 8 | 6.15 |
| 3 | 210 | 127.0 | 31.8 | 168.3 | 22.2 | 8 | 8.57 |
| 3 1/2 | 230 | 139.7 | 35.0 | 184.2 | 25.4 | 8 | 11.15 |
| 4 | 275 | 157.2 | 38.1 | 215.9 | 25.4 | 8 | 17.63 |
| 5 | 330 | 185.7 | 44.5 | 266.7 | 28.6 | 8 | 29.60 |
| 6 | 355 | 215.9 | 47.7 | 292.1 | 28.6 | 12 | 36.22 |
| 8 | 420 | 269.9 | 55.6 | 349.2 | 31.8 | 12 | 59.51 |
| 10 | 510 | 323.8 | 63.5 | 431.8 | 34.9 | 16 | 98.79 |
| 12 | 560 | 381.0 | 66.7 | 489.0 | 34.9 | 20 | 125.29 |
| 14 | 605 | 412.8 | 69.9 | 527.0 | 38.1 | 20 | 152.70 |
| 16 | 685 | 469.9 | 76.2 | 603.2 | 41.3 | 20 | 214.13 |
| 18 | 745 | 533.4 | 82.6 | 654.0 | 44.5 | 20 | 275.01 |
| 20 | 815 | 584.2 | 88.9 | 723.9 | 44.5 | 24 | 353.07 |
| 24 | 940 | 692.2 | 101.6 | 838.2 | 50.8 | 24 | 535.77 |
