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 | 12.7 | 66.7 | 15.9 | 4 | 0.64 |
| 3/4 | 115 | 42.9 | 14.3 | 82.6 | 19.1 | 4 | 1.06 |
| 1 | 125 | 50.8 | 15.9 | 88.9 | 19.1 | 4 | 1.42 |
| 1 1/4 | 135 | 63.5 | 17.5 | 98.4 | 19.1 | 4 | 1.86 |
| 1 1/2 | 155 | 73.0 | 19.1 | 114.3 | 22.2 | 4 | 2.66 |
| 2 | 165 | 92.1 | 20.7 | 127.0 | 19.1 | 8 | 3.21 |
| 2 1/2 | 190 | 104.8 | 23.9 | 149.2 | 22.2 | 8 | 4.88 |
| 3 | 210 | 127.0 | 27.0 | 168.3 | 22.2 | 8 | 6.89 |
| 3 1/2 | 230 | 139.7 | 28.6 | 184.2 | 22.2 | 8 | 8.88 |
| 4 | 255 | 157.2 | 30.2 | 200.0 | 22.2 | 8 | 11.68 |
| 5 | 280 | 185.7 | 33.4 | 235.0 | 22.2 | 8 | 15.77 |
| 6 | 320 | 215.9 | 35.0 | 269.9 | 22.2 | 12 | 21.41 |
| 8 | 380 | 269.9 | 39.7 | 330.2 | 25.4 | 12 | 34.37 |
| 10 | 445 | 323.8 | 46.1 | 387.4 | 28.6 | 16 | 53.90 |
| 12 | 520 | 381.0 | 49.3 | 450.8 | 31.8 | 16 | 79.14 |
| 14 | 585 | 412.8 | 52.4 | 514.4 | 31.8 | 20 | 106.23 |
| 16 | 650 | 469.9 | 55.6 | 571.5 | 34.9 | 20 | 139.30 |
| 18 | 710 | 533.4 | 58.8 | 628.6 | 34.9 | 24 | 175.78 |
| 20 | 775 | 584.2 | 62.0 | 685.8 | 34.9 | 24 | 222.78 |
| 24 | 915 | 692.2 | 68.3 | 812.8 | 41.3 | 24 | 341.50 |
