Technical information / Connection standards / ASME B16.5 · Weld neck flange
End connection standard
ASME B16.5 · WELDING NECK
Weld neck flange dimensions
The CSV uses semicolons as separators. The link carries the selected class and size.
| NPS | DN | D | k | n | lhole | b | g | f | Pipe Øweld bevel | Ahub base | Hlength |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 1/2" | DN15 | 89 | 60.3 | 4 | 15.9 | 11.1 | 34.9 | 1.6 | 21.3 | 30 | 47.6 |
| 3/4" | DN20 | 98 | 69.8 | 4 | 15.9 | 12.7 | 42.9 | 1.6 | 26.7 | 38 | 52.6 |
| 1" | DN25 | 108 | 79.4 | 4 | 15.9 | 14.3 | 50.8 | 1.6 | 33.4 | 49.2 | 55.6 |
| 1 1/4" | DN32 | 117 | 88.9 | 4 | 15.9 | 15.9 | 63.5 | 1.6 | 42.2 | 59 | 57.6 |
| 1 1/2" | DN40 | 127 | 98.4 | 4 | 15.9 | 17.5 | 73.2 | 1.6 | 48.3 | 65 | 61.6 |
| 2" | DN50 | 152 | 120.6 | 4 | 19 | 19 | 92.1 | 1.6 | 60.3 | 78 | 63.6 |
| 2 1/2" | DN65 | 178 | 139.7 | 4 | 19.1 | 22.3 | 104.6 | 1.6 | 73 | 90 | 69.6 |
| 3" | DN80 | 190 | 152.4 | 4 | 19 | 23.8 | 127 | 1.6 | 88.9 | 108 | 69.6 |
| 3 1/2" | DN90 | 216 | 177.8 | 8 | 19.1 | 23.9 | 139.7 | 1.6 | 101.6 | 122 | 71.6 |
| 4" | DN100 | 229 | 190.5 | 8 | 19 | 23.8 | 157.2 | 1.6 | 114.3 | 135 | 76.6 |
| 5" | DN125 | 254 | 215.9 | 8 | 22.2 | 23.8 | 185.7 | 1.6 | 141.3 | 164 | 88.6 |
| 6" | DN150 | 279 | 241.3 | 8 | 22.2 | 25.4 | 215.9 | 1.6 | 168.3 | 192 | 88.6 |
| 8" | DN200 | 343 | 298.4 | 8 | 22.2 | 28.6 | 269.9 | 1.6 | 219 | 246 | 101.6 |
| 10" | DN250 | 406 | 362 | 12 | 25.4 | 30.2 | 323.8 | 1.6 | 273 | 305 | 101.6 |
| 12" | DN300 | 483 | 431.8 | 12 | 25.4 | 31.8 | 381 | 1.6 | 323.9 | 365 | 114.6 |
| 14" | DN350 | 533 | 476.2 | 12 | 28.6 | 34.9 | 412.7 | 1.6 | 355 | 400 | 126.6 |
| 16" | DN400 | 597 | 539.7 | 16 | 28.6 | 36.5 | 469.9 | 1.6 | 406.4 | 457 | 126.6 |
| 18" | DN450 | 635 | 577.8 | 16 | 31.8 | 39.7 | 533.4 | 1.6 | 457.2 | 505 | 139.6 |
| 20" | DN500 | 698 | 635 | 20 | 31.8 | 42.9 | 584.2 | 1.6 | 508 | 560 | 144.6 |
| 24" | DN600 | 813 | 749.3 | 20 | 34.9 | 47.6 | 692.1 | 1.6 | 610 | 663 | 152.6 |
Notes
- This table has been compiled by Emsal from the relevant standards. For the full text of the standard, refer to ASME.
- Connection dimensions and thickness are the same as the slip-on flange of the same class and size; dimensions are converted from the standard's inch values.
- Raised face (f): 1.6 mm for Class 150 and 300 and included in the thickness (b) and hub length (H); 6.4 mm for Class 600 and 900 and not included in these dimensions (ASME B16.5).
- The bore depends on the pipe wall thickness (schedule); it is indicative in the drawing.
- Accuracy and currency are not guaranteed; use the current edition of the standard for design and purchasing decisions. How the library is compiled →
Dimension letters
| D | Flange outside diameter | g | Raised face diameter |
| k | Bolt circle diameter | f | Raised face height |
| l | Bolt hole diameter | n | Number of bolts |
| b | Flange thickness | A | Hub diameter at base |
| H | Length through hub | Pipe Ø: outside diameter at weld bevel |
Joint type and P&ID symbol
The neck of a weld neck flange is butt-welded to the pipe. The weld is full penetration and can be radiographed.
flangepipegasketweldbolt, nut
- Bevel the neck and the pipe end at the weld bevel angle; the bores (schedule) must match.
- Make a full-penetration butt weld; radiograph if required.
- Fit the gasket and tighten the bolts in a cross pattern.
The tapered neck spreads stress into the pipe; it is the standard choice for high pressure, high temperature and vibration. The smooth bore does not disturb the flow.
P&ID: Flanged jointTwo short heavy lines perpendicular to the pipeline; the flange type is not shown on the diagram but given in the line list. Symbol library →
Not to scale; proportions are indicative.
