What Are ASME B16.9 Elbows?
ASME B16.9 factory-made wrought buttwelding elbows change piping direction from NPS 1/2 through NPS 48. The standard covers 90-degree and 45-degree elbows in long radius (LR, 1.5D) and short radius (SR, 1.0D) center-to-end dimensions, with tolerances, welding-end bevels, and material requirements.Table 6.1-1 below lists the long radius 90° center-to-end dimension A and the long radius 45° center-to-end dimension B.
Long Radius vs Short Radius
- Long Radius (LR): center-to-end = 1.5 × NPS outside diameter. Most common design; lower pressure drop.
- Short Radius (SR): center-to-end = 1.0 × NPS outside diameter. Used where space is tight. Dimensions per ASME B16.9 Table 6.1-4.
- 45° LR elbows: dimension B as shown in Table 6.1-1 below.
- Long radius reducing elbows: dimensions per ASME B16.9 Table 6.1-2.
- 3D radius elbows: dimensions per ASME B16.9 Table 6.1-6.
Dimensions — Long Radius Elbows (Table 6.1-1)
NPS 1/2 – 48. Values in mm (inch). A = center-to-end 90° LR elbow; B = center-to-end 45° LR elbow; OD = outside diameter.
| NPS | Outside Diameter (mm / in) | A — 90° LR Center-to-End (mm / in) | B — 45° LR Center-to-End (mm / in) |
|---|---|---|---|
| 1/2 | 21.3 (0.84) | 38.0 (1.5) | 16.0 (0.62) |
| 3/4 | 26.7 (1.05) | 38.0 (1.5) | 19.0 (0.75) |
| 1 | 33.4 (1.32) | 38.0 (1.5) | 22.0 (0.88) |
| 1-1/4 | 42.2 (1.66) | 48.0 (1.88) | 25.0 (1.0) |
| 1-1/2 | 48.3 (1.9) | 57.0 (2.25) | 29.0 (1.12) |
| 2 | 60.3 (2.38) | 76.0 (3.0) | 35.0 (1.38) |
| 2-1/2 | 73.0 (2.88) | 95.0 (3.75) | 44.0 (1.75) |
| 3 | 88.9 (3.5) | 114.0 (4.5) | 51.0 (2.0) |
| 3-1/2 | 101.6 (4.0) | 133.0 (5.25) | 57.0 (2.25) |
| 4 | 114.3 (4.5) | 152.0 (6.0) | 64.0 (2.5) |
| 5 | 141.3 (5.56) | 190.0 (7.5) | 79.0 (3.12) |
| 6 | 168.3 (6.62) | 229.0 (9.0) | 95.0 (3.75) |
| 8 | 219.1 (8.62) | 305.0 (12.0) | 127.0 (5.0) |
| 10 | 273.0 (10.75) | 381.0 (15.0) | 159.0 (6.25) |
| 12 | 323.8 (12.75) | 457.0 (18.0) | 190.0 (7.5) |
| 14 | 355.6 (14.0) | 533.0 (21.0) | 222.0 (8.75) |
| 16 | 406.4 (16.0) | 610.0 (24.0) | 254.0 (10.0) |
| 18 | 457.0 (18.0) | 686.0 (27.0) | 286.0 (11.25) |
| 20 | 508.0 (20.0) | 762.0 (30.0) | 318.0 (12.5) |
| 22 | 559.0 (22.0) | 838.0 (33.0) | 343.0 (13.5) |
| 24 | 610.0 (24.0) | 914.0 (36.0) | 381.0 (15.0) |
| 26 | 660.0 (26.0) | 991.0 (39.0) | 406.0 (16.0) |
| 28 | 711.0 (28.0) | 1067.0 (42.0) | 438.0 (17.25) |
| 30 | 762.0 (30.0) | 1143.0 (45.0) | 470.0 (18.5) |
| 32 | 813.0 (32.0) | 1219.0 (48.0) | 502.0 (19.75) |
| 34 | 864.0 (34.0) | 1295.0 (51.0) | 533.0 (21.0) |
| 36 | 914.0 (36.0) | 1372.0 (54.0) | 565.0 (22.25) |
| 38 | 965.0 (38.0) | 1448.0 (57.0) | 600.0 (23.62) |
| 40 | 1016.0 (40.0) | 1524.0 (60.0) | 632.0 (24.88) |
| 42 | 1067.0 (42.0) | 1600.0 (63.0) | 660.0 (26.0) |
| 44 | 1118.0 (44.0) | 1676.0 (66.0) | 695.0 (27.38) |
| 46 | 1168.0 (46.0) | 1753.0 (69.0) | 727.0 (28.62) |
| 48 | 1219.0 (48.0) | 1829.0 (72.0) | 759.0 (29.88) |
Short radius elbows (90°) dimensions per ASME B16.9 Table 6.1-4; short radius 45° elbows follow the same SR radius rule.
Materials & Temperature Range
Elbows are manufactured from wrought materials: A234 WPB carbon steel (-29°C to 425°C), A403 WP304 / WP316 stainless steel (up to 538°C), and A420 WPL6 low-temperature carbon steel. Chemistry and mechanical properties per the applicable ASTM material standard.
Related Standards
- ASME B16.9 — Buttwelding Fittings (parent standard)
- ASME B16.9 Tees — Equal & Reducing
- ASME B16.9 Reducers — Concentric & Eccentric
- ASME B16.9 Pipe Caps
- ASME B16.9 180° Returns
- ASME B16.9 Lap Joint Stub Ends
- ASME B16.5 — Pipe Flanges
- ASTM A234 WPB Carbon Steel
- Our Fittings Range
FAQ
What is the difference between long radius and short radius elbows?
Long radius (LR) elbows have a center-to-end dimension of 1.5 times the pipe outside diameter; short radius (SR) elbows use 1.0 times. LR is the default choice; SR is used only when space is limited.
What does dimension A mean in Table 6.1-1?
A is the center-to-end distance of a long radius 90° elbow. B in the same table is the center-to-end distance of a long radius 45° elbow.
What sizes do ASME B16.9 elbows cover?
Factory-made buttwelding elbows from NPS 1/2 through NPS 48, in long radius as standard; short radius per Table 6.1-4.
Which material should I choose for elbows?
A234 WPB for general carbon steel service, A403 WP304/WP316 for corrosion resistance, and A420 WPL6 for low-temperature service. All follow the applicable ASTM material specification.
Are 45-degree elbow dimensions in Table 6.1-1?
Yes — the B column of Table 6.1-1 gives the long radius 45° center-to-end dimension. Short radius 45° elbows follow Table 6.1-4.
Can you manufacture reducing elbows to B16.9?
Yes — long radius reducing elbows follow Table 6.1-2; specify run and branch sizes on your enquiry.
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