ASME B16.9 sets the dimensions of factory-made wrought butt welding fittings from NPS 1/2 to 48. The chart below lists the dimensions buyers and piping designers need most often for the common sizes from 1/2" to 24" NPS, in millimetres. Centre-to-end and end-to-end dimensions are the same for every wall thickness; the wall thickness itself follows the pipe schedule ordered.
Elbows, tees, reducers and caps: dimensions in mm
| NPS | OD at bevel | A · 90° LR elbow | B · 45° LR elbow | SR · 90° SR elbow | C · Equal tee | H · Reducer | E · Cap |
|---|---|---|---|---|---|---|---|
| 1/2" | 21.3 | 38 | 16 | — | 25 | — | 25 |
| 3/4" | 26.7 | 38 | 19 | — | 29 | 38 | 25 |
| 1" | 33.4 | 38 | 22 | 25 | 38 | 51 | 38 |
| 1-1/4" | 42.2 | 48 | 25 | 32 | 48 | 51 | 38 |
| 1-1/2" | 48.3 | 57 | 29 | 38 | 57 | 64 | 38 |
| 2" | 60.3 | 76 | 35 | 51 | 64 | 76 | 38 |
| 2-1/2" | 73.0 | 95 | 44 | 64 | 76 | 89 | 38 |
| 3" | 88.9 | 114 | 51 | 76 | 86 | 89 | 51 |
| 4" | 114.3 | 152 | 64 | 102 | 105 | 102 | 64 |
| 6" | 168.3 | 229 | 95 | 152 | 143 | 140 | 89 |
| 8" | 219.1 | 305 | 127 | 203 | 178 | 152 | 102 |
| 10" | 273.0 | 381 | 159 | 254 | 216 | 178 | 127 |
| 12" | 323.8 | 457 | 190 | 305 | 254 | 203 | 152 |
| 14" | 355.6 | 533 | 222 | 356 | 279 | 330 | 165 |
| 16" | 406.4 | 610 | 254 | 406 | 305 | 356 | 178 |
| 18" | 457.0 | 686 | 286 | 457 | 343 | 381 | 203 |
| 20" | 508.0 | 762 | 318 | 508 | 381 | 508 | 229 |
| 24" | 610.0 | 914 | 381 | 610 | 432 | 508 | 267 |
"—" means the fitting is not listed in that size in ASME B16.9. Cap length E applies up to a limiting wall thickness; caps for heavier walls use the longer length E1, which is not shown here. Tolerances, reducing-tee outlet dimensions and sizes above 24" are given in the standard.
How to read the chart
- Long radius (LR) elbows have a bend radius of 1.5 × NPS, so from 1" upward dimension A is 1.5 times the nominal size in inches (converted to mm).
- Short radius (SR) elbows have a bend radius of 1.0 × NPS and save space at the cost of a higher pressure drop.
- Tees: C is measured from the centre of the run to the end of the run and of the outlet on an equal tee.
- Reducers: H is the overall length and is the same for concentric and eccentric reducers of the same large-end size.
- OD at bevel equals the outside diameter of the matching pipe, so fittings line up with pipe to ASME B36.10M / B36.19M.
This guide is a general reference summarised from the named standards. Always design, specify and inspect to the current edition of the applicable standard and your project specification. Published 2026-10-19.