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 | 135 | 34.9 | 30.2 | 88.9 | 22.2 | 4 | 3.08 |
| 3/4 | 140 | 42.9 | 31.8 | 95.2 | 22.2 | 4 | 3.54 |
| 1 | 160 | 50.8 | 35.0 | 108.0 | 25.4 | 4 | 5.08 |
| 1 1/4 | 185 | 63.5 | 38.1 | 130.2 | 28.6 | 4 | 7.45 |
| 1 1/2 | 205 | 73.0 | 44.5 | 146.0 | 31.8 | 4 | 10.66 |
| 2 | 235 | 92.1 | 50.9 | 171.4 | 28.6 | 8 | 15.66 |
| 2 1/2 | 265 | 104.8 | 57.2 | 196.8 | 31.8 | 8 | 22.41 |
| 3 | 305 | 127.0 | 66.7 | 228.6 | 34.9 | 8 | 34.96 |
| 4 | 355 | 157.2 | 76.2 | 273.0 | 41.3 | 8 | 53.91 |
| 5 | 420 | 185.7 | 92.1 | 323.8 | 47.6 | 8 | 91.42 |
| 6 | 485 | 215.9 | 108.0 | 368.3 | 54.0 | 8 | 143.23 |
| 8 | 550 | 269.9 | 127.0 | 438.2 | 54.0 | 12 | 212.79 |
| 10 | 675 | 323.8 | 165.1 | 539.8 | 66.7 | 12 | 414.32 |
| 12 | 760 | 381.0 | 184.2 | 619.1 | 73.0 | 12 | 589.99 |
