Long Neck Welding (abbreviated LWN) flanges are similar to a standard Welding Neck flange, but the “Neck” is considerably longer. This type is often used as a nozzle for a barrel or column. In addition, there are the type LWN Heavy Barrel (HB) and the Equal LWN Barrel (E); they have a different shape and a thicker “Wall”.

ASME B16.5 Long Weld Neck Flange Class 150 LBS Dimensions | ||||||||
NPS | O | Tf | X | B | Y | W | BH | Holes |
1/2″ | 88.9 | 9.7 | 30.2 | 12.7 | 228.6 | 60.5 | 15.9 | 4 |
3/4″ | 98.6 | 11.2 | 38.1 | 19.1 | 228.6 | 69.9 | 15.9 | 4 |
1″ | 108.0 | 12.7 | 49.3 | 25.4 | 228.6 | 79.2 | 15.9 | 4 |
1-1/4″ | 117.5 | 14.2 | 58.7 | 31.8 | 228.6 | 88.9 | 15.9 | 4 |
1-1/2″ | 127.0 | 15.7 | 65.0 | 38.1 | 228.6 | 98.6 | 15.9 | 4 |
2″ | 152.4 | 17.5 | 77.7 | 50.8 | 228.6 | 120.7 | 19.1 | 4 |
2-1/2″ | 177.8 | 20.6 | 90.4 | 63.5 | 228.6 | 139.7 | 19.1 | 4 |
3″ | 190.5 | 22.4 | 108.0 | 76.2 | 228.6 | 152.4 | 19.1 | 4 |
3-1/2″ | 215.9 | 22.4 | 122.2 | 88.9 | 228.6 | 177.8 | 19.1 | 8 |
4″ | 228.6 | 22.4 | 134.9 | 101.6 | 228.6 | 190.5 | 19.1 | 8 |
5″ | 254.0 | 22.4 | 163.6 | 127.0 | 304.8 | 215.9 | 22.2 | 8 |
6″ | 279.4 | 23.9 | 192.0 | 152.4 | 304.8 | 241.3 | 22.2 | 8 |
8″ | 342.9 | 26.9 | 246.1 | 203.2 | 304.8 | 298.5 | 22.2 | 8 |
10″ | 406.4 | 28.4 | 304.8 | 254.0 | 304.8 | 362.0 | 25.4 | 12 |
12″ | 482.6 | 30.2 | 365.3 | 304.8 | 304.8 | 431.8 | 25.4 | 12 |
14″ | 533.4 | 33.3 | 400.1 | 355.6 | 304.8 | 476.3 | 28.6 | 12 |
16″ | 596.9 | 35.1 | 457.2 | 406.4 | 304.8 | 539.8 | 28.6 | 16 |
18″ | 635.0 | 38.1 | 505.0 | 457.2 | 304.8 | 577.9 | 31.8 | 16 |
20″ | 698.5 | 41.1 | 558.8 | 508.0 | 304.8 | 635.0 | 31.8 | 20 |
24″ | 812.8 | 46.0 | 663.4 | 609.6 | 304.8 | 749.3 | 34.9 | 20 |
ASME B16.5 Long Weld Neck Flange Class 300 LBS Dimensions | ||||||||
NPS | O | Tf | X | B | Y | W | BH | Holes |
1/2″ | 95.3 | 12.7 | 38.1 | 12.7 | 228.6 | 66.5 | 15.9 | 4 |
3/4″ | 117.3 | 14.2 | 47.8 | 19.1 | 228.6 | 82.6 | 19.1 | 4 |
1″ | 124.0 | 15.7 | 53.8 | 25.4 | 228.6 | 88.9 | 19.1 | 4 |
1-1/4″ | 133.4 | 17.5 | 63.5 | 31.8 | 228.6 | 98.6 | 19.1 | 4 |
1-1/2″ | 155.4 | 19.1 | 69.9 | 38.1 | 228.6 | 114.3 | 22.2 | 4 |
2″ | 165.1 | 20.6 | 84.1 | 50.8 | 228.6 | 127.0 | 19.1 | 8 |
2-1/2″ | 190.5 | 23.9 | 100.1 | 63.5 | 228.6 | 149.4 | 22.2 | 8 |
3″ | 209.6 | 26.9 | 117.3 | 76.2 | 228.6 | 168.1 | 22.2 | 8 |
3-1/2″ | 228.6 | 28.4 | 133.4 | 88.9 | 228.6 | 184.2 | 22.2 | 8 |
4″ | 254.0 |
30.2 | 146.1 | 101.6 | 228.6 | 200.2 | 22.2 | 8 |
5″ | 279.4 | 33.3 | 177.8 | 127.0 | 304.8 | 235.0 | 22.2 | 8 |
6″ | 317.5 | 35.1 | 206.2 | 152.4 | 304.8 | 269.7 | 22.2 | 12 |
8″ | 381.0 | 39.6 | 260.4 | 203.2 | 304.8 | 330.2 | 25.4 | 12 |
10″ | 444.5 | 46.0 | 320.5 | 254.0 | 304.8 | 387.4 | 28.6 | 16 |
12″ | 520.7 | 49.3 | 374.7 | 304.8 | 304.8 | 450.9 | 31.8 | 16 |
14″ | 584.2 | 52.3 | 425.5 | 355.6 | 304.8 | 514.4 | 31.8 | 20 |
16″ | 647.7 | 55.6 | 482.6 | 406.4 | 304.8 | 571.5 | 34.9 | 20 |
18″ | 711.2 | 58.7 | 533.4 | 457.2 | 304.8 | 628.7 | 34.9 | 24 |
20″ | 774.7 | 62.0 | 587.2 | 508.0 | 304.8 | 685.8 | 34.9 | 24 |
24″ | 914.4 | 68.3 | 701.5 | 609.6 | 304.8 | 812.8 | 41.3 | 24 |
ASME B16.5 Long Weld Neck Flange Class 400 LBS Dimensions | ||||||||
NPS | O | Tf | X | B | Y | W | BH | Holes |
1/2″ | 95.3 | 14.2 | 38.1 | 12.7 | 228.6 | 66.5 | 15.9 | 4 |
3/4″ | 117.3 | 15.7 | 47.8 | 19.1 | 228.6 | 82.6 | 19.1 | 4 |
1″ | 124 | 17.5 | 53.8 | 25.4 | 228.6 | 88.9 | 19.1 | 4 |
1-1/4″ | 133.4 | 20.6 | 63.5 | 31.8 | 228.6 | 98.6 | 19.1 | 4 |
1-1/2″ | 155.4 | 22.4 | 69.9 | 38.1 | 228.6 | 114.3 | 22.2 | 4 |
2″ | 165.1 | 25.4 | 84.1 | 50.8 | 228.6 | 127 | 19.1 | 8 |
2-1/2″ | 190.5 | 28.4 | 100.1 | 63.5 | 228.6 | 149.4 | 22.2 | 8 |
3″ | 209.6 | 31.8 | 117.3 | 76.2 | 228.6 | 168.1 | 22.2 | 8 |
3-1/2″ | 228.6 | 35.1 | 133.4 | 88.9 | 228.6 | 184.2 | 25.4 | 8 |
4″ | 254 | 35.1 | 146.1 | 101.6 | 228.6 | 200.2 | 25.4 | 8 |
5″ | 279.4 | 38.1 | 177.8 | 127 | 304.8 | 235 | 25.4 | 8 |
6″ | 317.5 | 41.1 | 206.2 | 152.4 | 304.8 | 269.7 | 25.4 | 12 |
8″ | 381 | 47.8 | 260.4 | 203.2 | 304.8 | 330.2 | 28.6 | 12 |
10″ | 444.5 | 53.8 | 320.5 | 254 | 304.8 | 387.4 | 31.8 | 16 |
12″ | 520.7 | 57.2 | 374.7 | 304.8 | 304.8 | 450.9 | 34.9 | 16 |
14″ | 584.2 | 60.5 | 425.5 | 355.6 | 304.8 | 514.4 | 34.9 | 20 |
16″ | 647.7 | 63.5 | 482.6 | 406.4 | 304.8 | 571.5 | 38.1 | 20 |
18″ | 711.2 | 66.5 | 533.4 | 457.2 | 304.8 | 628.7 | 38.1 | 24 |
20″ | 774.7 | 69.9 | 587.2 | 508 | 304.8 | 685.8 | 41.3 | 24 |
24″ | 914.4 | 76.2 | 701.5 | 609.6 | 304.8 | 812.8 | 47.6 | 24 |
ASME B16.5 Long Weld Neck Flange Class 600 LBS Dimensions | ||||||||
NPS | O | Tf | X | B | Y | W | BH | Holes |
1/2″ | 95.3 | 14.2 | 38.1 | 12.7 | 228.6 | 66.5 | 15.9 | 4 |
3/4″ | 117.3 | 15.7 | 47.8 | 19.1 | 228.6 | 82.6 | 19.1 | 4 |
1″ | 124 | 17.5 | 53.8 | 25.4 | 228.6 | 88.9 | 19.1 | 4 |
1-1/4″ | 133.4 | 20.6 | 63.5 | 31.8 | 228.6 | 98.6 | 19.1 | 4 |
1-1/2″ | 155.4 | 22.4 | 69.9 | 38.1 | 228.6 | 114.3 | 22.2 | 4 |
2″ | 165.1 | 25.4 | 84.1 | 50.8 | 228.6 | 127 | 19.1 | 8 |
2-1/2″ | 190.5 | 28.4 | 100.1 | 63.5 | 228.6 | 149.4 | 22.2 | 8 |
3″ | 209.6 | 31.8 | 117.3 | 76.2 | 228.6 | 168.1 | 22.2 | 8 |
3-1/2″ | 228.6 | 35.1 | 133.4 | 88.9 | 228.6 | 184.2 | 25.4 | 8 |
4″ | 273.1 | 38.1 | 152.4 | 101.6 | 228.6 | 215.9 | 25.4 | 8 |
5″ | 330.2 | 44.5 | 189 | 127 | 304.8 | 266.7 | 28.6 | 8 |
6″ | 355.6 | 47.8 | 222.3 | 152.4 | 304.8 | 292.1 | 28.6 | 12 |
8″ | 419.1 | 55.6 | 273.1 | 203.2 | 304.8 | 349.3 | 31.8 | 12 |
10″ | 508 | 63.5 | 342.9 | 254 | 304.8 | 431.8 | 34.9 | 16 |
12″ | 558.8 | 66.5 | 400.1 | |||||