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 Pipe 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 | 90 | 34.9 | 9.6 | 60.3 | 15.9 | 4 | 0.44 |
| 3/4 | 100 | 42.9 | 11.2 | 69.9 | 15.9 | 4 | 0.64 |
| 1 | 110 | 50.8 | 12.7 | 79.4 | 15.9 | 4 | 0.90 |
| 1 1/4 | 115 | 63.5 | 14.3 | 88.9 | 15.9 | 4 | 1.13 |
| 1 1/2 | 125 | 73.0 | 15.9 | 98.4 | 15.9 | 4 | 1.50 |
| 2 | 150 | 92.1 | 17.5 | 120.7 | 19.1 | 4 | 2.38 |
| 2 1/2 | 180 | 104.8 | 20.7 | 139.7 | 19.1 | 4 | 4.09 |
| 3 | 190 | 127.0 | 22.3 | 152.4 | 19.1 | 4 | 4.97 |
| 3 1/2 | 215 | 139.7 | 22.3 | 177.8 | 19.1 | 8 | 6.20 |
| 4 | 230 | 157.2 | 22.3 | 190.5 | 19.1 | 8 | 7.18 |
| 5 | 255 | 185.7 | 22.3 | 215.9 | 22.2 | 8 | 8.83 |
| 6 | 280 | 215.9 | 23.9 | 241.3 | 22.2 | 8 | 11.55 |
| 8 | 345 | 269.9 | 27.0 | 298.5 | 22.2 | 8 | 20.07 |
| 10 | 405 | 323.8 | 28.6 | 362.0 | 25.4 | 12 | 28.87 |
| 12 | 485 | 381.0 | 30.2 | 431.8 | 25.4 | 12 | 44.18 |
| 14 | 535 | 412.8 | 33.4 | 476.3 | 28.6 | 12 | 59.07 |
| 16 | 595 | 469.9 | 35.0 | 539.8 | 28.6 | 16 | 76.36 |
| 18 | 635 | 533.4 | 38.1 | 577.9 | 31.8 | 16 | 94.51 |
| 20 | 700 | 584.2 | 41.3 | 635.0 | 31.8 | 20 | 123.94 |
| 24 | 815 | 692.2 | 46.1 | 749.3 | 34.9 | 20 | 187.90 |
