The Welding neck flanges is normally referred to as the high hub flange. It is designed to transfer stresses to the pipe, thereby reducing high stress concentrations at the base of the flange. The welding neck flange is the best designed butt-welded flange of those currently available because of its inherent structural value. It is expensive because of the design.
| Nominal Pipe Size | Outside Diameter of Flange | Diameter of Raised Face | Thickness of Flanges Min. | Diameter of Hub | Hub Diameter Beginning of Chamfer | Length Through Hub | Bore | Diameter of Bolt Circle | Diameter of Bolt Holes | Number of Bolts | Approxi-mate Weight kgs |
| NPS | O | R | tf | X | A | Y | B | W | I | n | |
| 1/2 | 135 | 34.9 | 30.2 | 43 | 21.3 | 73 | 15.8 | 88.9 | 22.2 | 4 | 3.23 |
| 3/4 | 140 | 42.9 | 31.8 | 51 | 26.7 | 79 | 21.0 | 95.2 | 22.2 | 4 | 3.74 |
| 1 | 160 | 50.8 | 35.0 | 57 | 33.4 | 89 | 26.6 | 108.0 | 25.4 | 4 | 5.34 |
| 1 1/4 | 185 | 63.5 | 38.1 | 73 | 42.2 | 95 | 35.1 | 130.2 | 28.6 | 4 | 7.84 |
| 1 1/2 | 205 | 73.0 | 44.5 | 79 | 48.3 | 111 | 40.9 | 146.0 | 31.8 | 4 | 11.10 |
| 2 | 235 | 92.1 | 50.9 | 95 | 60.3 | 127 | 52.5 | 171.4 | 28.6 | 8 | 16.21 |
| 2 1/2 | 265 | 104.8 | 57.2 | 114 | 73.0 | 143 | 62.7 | 196.8 | 31.8 | 8 | 23.40 |
| 3 | 305 | 127.0 | 66.7 | 133 | 88.9 | 168 | 77.9 | 228.6 | 34.9 | 8 | 36.10 |
| 4 | 355 | 157.2 | 76.2 | 165 | 114.3 | 190 | 102.3 | 273.0 | 41.3 | 8 | 54.89 |
| 5 | 420 | 185.7 | 92.1 | 203 | 141.3 | 229 | 128.2 | 323.8 | 47.6 | 8 | 92.52 |
| 6 | 485 | 215.9 | 108.0 | 235 | 168.3 | 273 | 154.1 | 368.3 | 54.0 | 8 | 143.61 |
| 8 | 550 | 269.9 | 127.0 | 305 | 219.1 | 318 | 202.7 | 438.2 | 54.0 | 12 | 211.29 |
| 10 | 675 | 323.8 | 165.1 | 375 | 273.0 | 419 | 254.5 | 539.8 | 66.7 | 12 | 408.58 |
| 12 | 760 | 381.0 | 184.2 | 441 | 323.8 | 464 | 304.7 | 619.1 | 73.0 | 12 | 572.56 |
