Butt-weld fittings dimensions: elbows, tees, reducers and caps to ASME B16.9 and EN 10253
Centre-to-end dimensions of 90° and 45° elbows, equal tees, reducers and caps to ASME B16.9 for NPS ½" to 24", long and short radius elbows, concentric and eccentric reducers, and how EN 10253 fittings differ.
Updated October 17, 2026
Butt-weld fittings change the direction, size or end of a pipe and are welded to it end to end. Their outside diameter and wall match the pipe; their length is fixed by the standard, so a piping layout can be drawn before the fittings arrive. The tables below give the centre-to-end and overall dimensions to ASME B16.9, the standard most drawings refer to.
What to specify when ordering
- Type — elbow (90°, 45° or 180°, long or short radius), equal or reducing tee, concentric or eccentric reducer, cap.
- Size — NPS or DN, and for reducers and reducing tees both sizes, larger end first: 4" × 2".
- Wall — the same schedule as the pipe, such as Sch 40 or STD, or a wall in mm. See the pipe schedule chart.
- Material — for example ASTM A234 WPB or EN 10253-2 P235GH for carbon steel, ASTM A403 WP304 or WP316L for stainless steel.
- Ends — bevelled for welding, normally 37.5° to ASME B16.25.
Elbow dimensions
| NPS | DN | OD | 90° long radius A | 45° long radius B | 90° short radius A |
|---|---|---|---|---|---|
| ½" | 15 | 21.3 | 38.1 | 15.7 | – |
| ¾" | 20 | 26.7 | 28.6 | 11.2 | – |
| 1" | 25 | 33.4 | 38.1 | 22.4 | 25.4 |
| 1¼" | 32 | 42.2 | 47.6 | 25.4 | 31.8 |
| 1½" | 40 | 48.3 | 57.2 | 28.4 | 38.1 |
| 2" | 50 | 60.3 | 76.2 | 35.1 | 50.8 |
| 2½" | 65 | 73.0 | 95.3 | 44.5 | 63.5 |
| 3" | 80 | 88.9 | 114.3 | 50.8 | 76.2 |
| 3½" | 90 | 101.6 | 133.4 | 57.2 | 88.9 |
| 4" | 100 | 114.3 | 152.4 | 63.5 | 101.6 |
| 5" | 125 | 141.3 | 190.5 | 79.2 | 127.0 |
| 6" | 150 | 168.3 | 228.6 | 95.3 | 152.4 |
| 8" | 200 | 219.1 | 304.8 | 127.0 | 203.2 |
| 10" | 250 | 273.1 | 381.0 | 158.8 | 254.0 |
| 12" | 300 | 323.9 | 457.2 | 190.5 | 304.8 |
| 14" | 350 | 355.6 | 533.4 | 222.3 | 355.6 |
| 16" | 400 | 406.4 | 609.6 | 254.0 | 406.4 |
| 18" | 450 | 457.0 | 685.8 | 285.8 | 457.2 |
| 20" | 500 | 508.0 | 762.0 | 317.5 | 508.0 |
| 24" | 600 | 610.0 | 914.4 | 381.0 | 609.6 |
- Long radius (LR) — bend radius 1.5 × NPS from ¾" upward. The default choice: lower pressure loss and easier pigging and cleaning.
- Short radius (SR) — bend radius 1.0 × NPS, for tight spaces. Higher pressure loss and usually a lower pressure rating than the pipe.
- 180° return — two 90° long radius elbows in one piece; the centre-to-centre distance is twice the 90° dimension.
- Bends with larger radii, such as 3D or 5D, are separate products made from pipe and are not covered by these tables.
Tees, reducers and caps
| NPS | DN | Equal tee C | Reducer H | Cap E |
|---|---|---|---|---|
| ½" | 15 | 25.4 | – | 25.4 |
| ¾" | 20 | 28.6 | 38.1 | 25.4 |
| 1" | 25 | 38.1 | 50.8 | 38.1 |
| 1¼" | 32 | 47.6 | 50.8 | 38.1 |
| 1½" | 40 | 57.2 | 63.5 | 38.1 |
| 2" | 50 | 63.5 | 76.2 | 38.1 |
| 2½" | 65 | 76.2 | 88.9 | 38.1 |
| 3" | 80 | 85.7 | 88.9 | 50.8 |
| 3½" | 90 | 95.3 | 101.6 | 63.5 |
| 4" | 100 | 104.8 | 101.6 | 63.5 |
| 5" | 125 | 123.8 | 127.0 | 76.2 |
| 6" | 150 | 142.9 | 139.7 | 88.9 |
| 8" | 200 | 177.8 | 152.4 | 101.6 |
| 10" | 250 | 215.9 | 177.8 | 127.0 |
| 12" | 300 | 254.0 | 203.2 | 152.4 |
| 14" | 350 | 279.4 | 330.2 | 165.1 |
| 16" | 400 | 304.8 | 355.6 | 177.8 |
| 18" | 450 | 342.9 | 381.0 | 203.2 |
| 20" | 500 | 381.0 | 508.0 | 228.6 |
| 24" | 600 | 431.8 | 508.0 | 266.7 |
- Equal tee — C is the distance from the centre to each of the three ends. A reducing tee keeps C on the run and has a shorter branch dimension.
- Reducer — H is the overall length, set by the larger end: a 4" × 2" and a 4" × 3" reducer are both 101.6 mm long.
- Cap — E applies up to a limiting wall thickness; heavier caps are longer.
Concentric or eccentric reducer?
A concentric reducer keeps both ends on the same centre line and suits vertical lines and most process piping. An eccentric reducer has one side flat. Install it flat side up on pump suction lines so that no air pocket forms, and flat side down on pipe racks so that the bottom of the pipe stays at one level.
EN 10253 fittings
European butt-weld fittings to EN 10253 (part 2 for carbon steel, part 4 for stainless steel) have elbow, tee and reducer lengths close to ASME B16.9, but they are made to the outside diameters of European pipe. At several sizes those differ: DN20 is 26.9 mm against 26.7 mm, DN65 is 76.1 mm against 73.0 mm and DN125 is 139.7 mm against 141.3 mm. Order fittings to the outside diameter of the pipe they are welded to, or the ends will not line up.
Fittings we supply
- Carbon steel — 90° elbows, 180° returns, equal tees, reducing tees, concentric and eccentric reducers and pipe caps.
- Stainless steel 304 — elbows, tees, concentric and eccentric reducers and caps.
- Matching flanges are listed in the flange dimensions guide.
Frequently asked questions
What is the centre-to-end dimension of a 4 inch 90° elbow?
A 4" 90° long radius elbow to ASME B16.9 measures 152.4 mm (6 in) from centre to end. The short radius version measures 101.6 mm, and a 4" 45° long radius elbow 63.5 mm.
What is the difference between long radius and short radius elbows?
A long radius elbow bends with a radius of 1.5 times the nominal size, a short radius elbow with 1.0 times. Long radius is the standard choice; short radius saves space but causes more pressure loss.
How long is a 6 inch reducer?
Every ASME B16.9 reducer with a 6" large end is 139.7 mm long, whatever the small end. The length depends only on the larger size.
Are DN and NPS fittings interchangeable?
Only where the outside diameters match, such as DN50 and 2" at 60.3 mm. At DN65 an EN fitting is 76.1 mm and an ASME fitting 73.0 mm, so the two do not weld together cleanly.
Send your fitting list with type, size, wall and material in a quote request. EN 10204 3.1 certificates are available on request.
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