Reference
ASME B16.9 buttweld fitting dimensions
Centre-to-end and end-to-end dimensions of elbows, tees, reducers and caps, NPS ½" to 24", in millimetres.
| NPS | OD | 90° LR elbow A | 45° elbow B | Tee C | Reducer H | Cap E |
|---|---|---|---|---|---|---|
| ½" | 21.3 | 38 | 16 | 25 | — | 25 |
| ¾" | 26.7 | 38 | 19 | 29 | 38 | 25 |
| 1" | 33.4 | 38 | 22 | 38 | 51 | 38 |
| 1¼" | 42.2 | 48 | 25 | 48 | 51 | 38 |
| 1½" | 48.3 | 57 | 29 | 57 | 64 | 38 |
| 2" | 60.3 | 76 | 35 | 64 | 76 | 38 |
| 2½" | 73.0 | 95 | 44 | 76 | 89 | 38 |
| 3" | 88.9 | 114 | 51 | 86 | 89 | 51 |
| 3½" | 101.6 | 133 | 57 | 95 | 102 | 64 |
| 4" | 114.3 | 152 | 64 | 105 | 102 | 64 |
| 5" | 141.3 | 190 | 79 | 124 | 127 | 76 |
| 6" | 168.3 | 229 | 95 | 143 | 140 | 89 |
| 8" | 219.1 | 305 | 127 | 178 | 152 | 102 |
| 10" | 273.1 | 381 | 159 | 216 | 178 | 127 |
| 12" | 323.9 | 457 | 190 | 254 | 203 | 152 |
| 14" | 355.6 | 533 | 222 | 279 | 330 | 165 |
| 16" | 406.4 | 610 | 254 | 305 | 356 | 178 |
| 18" | 457.0 | 686 | 286 | 343 | 381 | 203 |
| 20" | 508.0 | 762 | 318 | 381 | 508 | 229 |
| 24" | 610.0 | 914 | 381 | 432 | 508 | 267 |
Dimensions in mm per ASME B16.9. Reducer length H is given for the large-end size; cap length E is for standard wall. Material standards: ASTM A403 (stainless), A815 (duplex), B366 (nickel alloys), A234 (carbon and alloy steel).
Fitting dimensions — questions
What is the centre-to-end of a long-radius elbow?
1.5 times the nominal size for NPS ¾" and larger — for example 152 mm for a 4" 90° LR elbow. A short-radius elbow is 1 times the nominal size.
Which standard covers buttweld fitting dimensions?
ASME B16.9. The wall thickness of each fitting matches the schedule of the pipe it is welded to.
Are reducer lengths the same for concentric and eccentric reducers?
Yes, ASME B16.9 gives the same end-to-end length H for both, based on the large-end size.
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