Elbow — ASME B16.9
Elbow — a fitting that changes the direction of a pipe run. Elbows come in 45°, 90° and 180° (return) angles. Long-radius (1.5D) is the default for flow; short-radius (1D) saves space. Buttweld elbows follow ASME B16.9; socket-weld and threaded elbows follow ASME B16.11.
- ASME B16.9
- 22 grades
- EN 10204 3.1 / 3.2
Reviewed by the Kanak Steel & Engineering Co. technical team · Updated October 2026
What is an elbow?
An elbow is a fitting that changes the direction of a pipe run. Elbows come in 45°, 90° and 180° (return) angles. Long-radius (1.5D) is the default for flow; short-radius (1D) saves space. Buttweld elbows follow ASME B16.9; socket-weld and threaded elbows follow ASME B16.11.
Elbow: What to Know Before Ordering
- LR (1.5D) and SR (1D) radius
- 45°, 90° and 180° return
- Seamless or welded construction
Elbow Materials & Grades
| Grade | Material standard | Best for |
|---|---|---|
| Inconel 825 elbow | ASTM B366 WPNICMC (buttweld) · ASTM B564 (forged) | Sulphuric and phosphoric acid service, chloride stress-corrosion cracking and sour gas |
| SS 904L elbow | ASTM A403 WP904L (buttweld) · ASTM A182 F904L (forged) | Dilute sulphuric acid, phosphoric acid and chloride-bearing cooling water |
| SS 304 elbow | ASTM A403 WP304 (buttweld) · ASTM A182 F304 (forged) | General corrosion resistance, food, water and architectural work |
| SS 304L elbow | ASTM A403 WP304L (buttweld) · ASTM A182 F304L (forged) | Welded tanks, piping and vessels in general corrosive service |
| SS 310 / 310S elbow | ASTM A403 WP310S (buttweld) · ASTM A182 F310 (forged) | Furnaces, burners and heat treatment at high temperature |
| SS 316 / 316L elbow | ASTM A403 WP316L (buttweld) · ASTM A182 F316L (forged) | Chloride-bearing process fluids, marine air and pharmaceutical service |
| SS 321 elbow | ASTM A403 WP321 (buttweld) · ASTM A182 F321 (forged) | High-temperature service between 425 and 815 °C |
| SS 347 elbow | ASTM A403 WP347 (buttweld) · ASTM A182 F347 (forged) | Welded high-temperature piping in refineries and power plants |
| Duplex 2205 elbow | ASTM A815 WPS31803 / WPS32205 (buttweld) · ASTM A182 F51 / F60 (forged) | Strength with chloride resistance at a stainless-steel budget |
| Super Duplex 2507 elbow | ASTM A815 WPS32750 (buttweld) · ASTM A182 F53 (forged) | Seawater and high-chloride service where strength also matters |
| Inconel 600 elbow | ASTM B366 WPNCI (buttweld) · ASTM B564 (forged) | High-temperature oxidation, caustic and nuclear service |
| Inconel 625 elbow | ASTM B366 WPNCMC (buttweld) · ASTM B564 (forged) | Seawater, high strength and high temperature in one alloy |
| Inconel 718 elbow | a specification not yet established (buttweld) · a specification not yet established (forged) | Very high strength at temperatures up to about 650 °C |
| Incoloy 800 / 800H / 800HT elbow | ASTM B366 WPNIC (buttweld) · ASTM B564 (forged) | Furnaces, petrochemical heaters and high-temperature piping |
| Hastelloy C276 elbow | ASTM B366 WPHC276 (buttweld) · ASTM B462 / B564 (forged) | The most aggressive mixed acids, wet chlorine and hypochlorite |
| Hastelloy C22 elbow | ASTM B366 WPHC22 (buttweld) · ASTM B462 / B564 (forged) | Mixed oxidising and reducing acids, and weld overlays |
| Monel 400 elbow | ASTM B366 WPNC (buttweld) · ASTM B564 (forged) | Seawater, hydrofluoric acid and marine service |
| Super Duplex S32760 elbow | ASTM A815 WPS32760 (buttweld) · ASTM A182 F55 (forged) | Seawater firewater, injection and offshore piping |
| ASTM A106 Gr B elbow | ASTM A234 WPB (buttweld) · ASTM A105 (forged) | High-temperature process and steam piping in refineries and power plants |
| ASTM A333 Gr 6 elbow | ASTM A420 WPL6 (buttweld) · ASTM A350 LF2 (forged) | Cold-climate and refrigerated piping down to −45 °C |
| ASTM A335 P11 elbow | ASTM A234 WP11 (buttweld) · ASTM A182 F11 (forged) | Steam and hot-oil piping up to about 550 °C |
| ASTM A335 P22 elbow | ASTM A234 WP22 (buttweld) · ASTM A182 F22 (forged) | High-pressure steam and hydrogen service up to about 580 °C |
Other pipe fittings
Elbow dimensions — ASME B16.9
Values in mm, the same for every material; the wall thickness matches the pipe schedule.
| NPS | OD | 90° LR elbow A | 45° elbow B | 90° SR elbow |
|---|---|---|---|---|
| ½" | 21.3 | 38 | 16 | — |
| ¾" | 26.7 | 38 | 19 | — |
| 1" | 33.4 | 38 | 22 | 25 |
| 1½" | 48.3 | 57 | 29 | 38 |
| 2" | 60.3 | 76 | 35 | 51 |
| 3" | 88.9 | 114 | 51 | 76 |
| 4" | 114.3 | 152 | 64 | 102 |
| 6" | 168.3 | 229 | 95 | 152 |
| 8" | 219.1 | 305 | 127 | 203 |
| 10" | 273.1 | 381 | 159 | 254 |
| 12" | 323.9 | 457 | 190 | 305 |
| 16" | 406.4 | 610 | 254 | 406 |
| 20" | 508.0 | 762 | 318 | 508 |
| 24" | 610.0 | 914 | 381 | 610 |
Full chart: ASME B16.9 fitting dimensions.
Elbow — questions buyers ask
What is an elbow?
An elbow is a fitting that changes the direction of a pipe run. Elbows come in 45°, 90° and 180° (return) angles. Long-radius (1.5D) is the default for flow; short-radius (1D) saves space. Buttweld elbows follow ASME B16.9; socket-weld and threaded elbows follow ASME B16.11.
Long radius or short radius elbow?
Long radius gives lower pressure drop and is the default. Short radius is used where space is tight, with a small pressure-rating reduction per ASME B16.9.
Which grades are elbows available in?
Inconel 825, SS 904L, SS 304, SS 304L, SS 310 / 310S, SS 316 / 316L, SS 321, SS 347, Duplex 2205, Super Duplex 2507, Inconel 600, Inconel 625, Inconel 718, Incoloy 800 / 800H / 800HT, Hastelloy C276, Hastelloy C22, Monel 400, Super Duplex S32760, ASTM A106 Gr B, ASTM A333 Gr 6, ASTM A335 P11, ASTM A335 P22.
Which standard covers elbow dimensions?
ASME B16.9 · B16.11. The material standard depends on the grade.
Sources: the ASTM / ASME specifications named on this page and producer datasheets · Last updated October 2026