# Butt-weld reducers, concentric and eccentric (ASME B16.9), NPS ¾ to 12

> What is the end-to-end length of a butt-weld concentric or eccentric reducer (ASME B16.9)?

- Category: Tri-clamp & pipe › Pipe, tube & threads
- Kind: Standard part
- Basis: ASME B16.9 dimensions as published in SHIELD's manufacturer table (mm); OD and Sch 40 wall per ASME B36.10 (Weldbend)
- Page: https://xemstudio.com/objects/butt-weld-reducers/ · JSON: https://xemstudio.com/api/geometry?object=butt-weld-reducers · Plain text: https://xemstudio.com/objects/butt-weld-reducers/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); files CC BY 4.0 or their publisher's license
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**Exact dimensions.** True size, with no printing tolerance added.

## Notes

- Concentric and eccentric reducers share the same end-to-end length H for each size pair. An eccentric reducer keeps one side straight (flat side down in a pump suction, up for drainage).
- Files: 2 × 1 and 4 × 2, concentric and eccentric, Schedule 40 at each end. The shape of the transition is the manufacturer's: the files run a straight cone over the full length between the two ends.
- OD and Schedule 40 wall: Weldbend prints OD rounded (1.32, 2.38 in); the files use the exact ASME B36.10 OD (1.315, 2.375, 4.500 in) with the Weldbend Sch 40 wall (.133, .154, .237 in). Fittings are made to match the pipe's OD and wall.
- Ends are drawn square. Real fittings are bevelled for welding to ASME B16.25; no public, citable statement of the bevel was found, so it is not drawn.

## Sizes

| size, NPS | large-end OD, mm | small-end OD, mm | end-to-end H, mm |
|---|---|---|---|
| 3/4 × 3/8 | 26.7 | 17.3 | 38 |
| 3/4 × 1/2 | 26.7 | 21.3 | 38 |
| 1 × 1/2 | 33.4 | 21.3 | 51 |
| 1 × 3/4 | 33.4 | 26.7 | 51 |
| 1-1/4 × 1/2 | 42.2 | 21.3 | 51 |
| 1-1/4 × 3/4 | 42.2 | 26.7 | 51 |
| 1-1/4 × 1 | 42.2 | 33.4 | 51 |
| 1-1/2 × 1/2 | 48.3 | 21.3 | 64 |
| 1-1/2 × 3/4 | 48.3 | 26.7 | 64 |
| 1-1/2 × 1 | 48.3 | 33.4 | 64 |
| 1-1/2 × 1-1/4 | 48.3 | 42.2 | 64 |
| 2 × 3/4 | 60.3 | 26.7 | 76 |
| 2 × 1 | 60.3 | 33.4 | 76 |
| 2 × 1-1/4 | 60.3 | 42.2 | 76 |
| 2 × 1-1/2 | 60.3 | 48.3 | 76 |
| 2-1/2 × 1 | 73.0 | 33.4 | 89 |
| 2-1/2 × 1-1/4 | 73.0 | 42.2 | 89 |
| 2-1/2 × 1-1/2 | 73.0 | 48.3 | 89 |
| 2-1/2 × 2 | 73.0 | 60.3 | 89 |
| 3 × 1-1/4 | 88.9 | 42.2 | 89 |
| 3 × 1-1/2 | 88.9 | 48.3 | 89 |
| 3 × 2 | 88.9 | 60.3 | 89 |
| 3 × 2-1/2 | 88.9 | 73.0 | 89 |
| 3-1/2 × 1-1/4 | 101.6 | 42.2 | 102 |
| 3-1/2 × 1-1/2 | 101.6 | 48.3 | 102 |
| 3-1/2 × 2 | 101.6 | 60.3 | 102 |
| 3-1/2 × 2-1/2 | 101.6 | 73.0 | 102 |
| 3-1/2 × 3 | 101.6 | 88.9 | 102 |
| 4 × 1-1/2 | 114.3 | 48.3 | 102 |
| 4 × 2 | 114.3 | 60.3 | 102 |
| 4 × 2-1/2 | 114.3 | 73.0 | 102 |
| 4 × 3 | 114.3 | 88.9 | 102 |
| 4 × 3-1/2 | 114.3 | 101.6 | 102 |
| 5 × 2 | 141.3 | 60.3 | 127 |
| 5 × 2-1/2 | 141.3 | 73.0 | 127 |
| 5 × 3 | 141.3 | 88.9 | 127 |
| 5 × 3-1/2 | 141.3 | 101.6 | 127 |
| 5 × 4 | 141.3 | 114.3 | 127 |
| 6 × 2-1/2 | 168.3 | 73.0 | 140 |
| 6 × 3 | 168.3 | 88.9 | 140 |
| 6 × 3-1/2 | 168.3 | 101.6 | 140 |
| 6 × 4 | 168.3 | 114.3 | 140 |
| 6 × 5 | 168.3 | 141.3 | 140 |
| 8 × 3-1/2 | 219.1 | 101.6 | 152 |
| 8 × 4 | 219.1 | 114.3 | 152 |
| 8 × 5 | 219.1 | 141.3 | 152 |
| 8 × 6 | 219.1 | 168.3 | 152 |
| 10 × 4 | 273.0 | 114.3 | 178 |
| 10 × 5 | 273.0 | 141.3 | 178 |
| 10 × 6 | 273.0 | 168.3 | 178 |
| 10 × 8 | 273.0 | 219.1 | 178 |
| 12 × 5 | 323.8 | 141.3 | 203 |
| 12 × 6 | 323.8 | 168.3 | 203 |
| 12 × 8 | 323.8 | 219.1 | 203 |
| 12 × 10 | 323.8 | 273.0 | 203 |

## Where the files are

- SHIELD (manufacturer): [Butt-welded fittings & flanges, SG-BWFF: ASME B16.9 elbows, tees, reducers (mm)](https://www.naffco.com/media-downloads/pdf/buttwelded.pdf) — web — Publisher's page; dimensions are facts
- Weldbend Corporation: [Weld fitting & weld flange catalog, 63rd edition: 90° and 45° long-radius elbows, OD, STD / Sch 40 wall](https://acceldx.roccommercecloud.com/assets/86/84/86841a47-ae63-4c4d-9881-ceba74db0969/Weldbend_131010000_Catalog.pdf) — web — Publisher's page; dimensions are facts

## Free STEP/STL (4 parts, CC BY 4.0, Xem Studio)

Index: https://xemstudio.com/files/hardware/butt-weld-reducers/index.json

- bw-reducer-concentric-nps2x1-sch40: [STEP](https://xemstudio.com/files/hardware/butt-weld-reducers/bw-reducer-concentric-nps2x1-sch40.step) · [STL](https://xemstudio.com/files/hardware/butt-weld-reducers/bw-reducer-concentric-nps2x1-sch40.stl) — NPS 2 × 1 concentric reducer, Sch 40 each end, end-to-end 76 mm; drawn as a straight cone between the ends (transition shape not set by B16.9); square ends
- bw-reducer-eccentric-nps2x1-sch40: [STEP](https://xemstudio.com/files/hardware/butt-weld-reducers/bw-reducer-eccentric-nps2x1-sch40.step) · [STL](https://xemstudio.com/files/hardware/butt-weld-reducers/bw-reducer-eccentric-nps2x1-sch40.stl) — NPS 2 × 1 eccentric reducer, Sch 40 each end, end-to-end 76 mm; drawn as a straight cone between the ends (transition shape not set by B16.9); square ends
- bw-reducer-concentric-nps4x2-sch40: [STEP](https://xemstudio.com/files/hardware/butt-weld-reducers/bw-reducer-concentric-nps4x2-sch40.step) · [STL](https://xemstudio.com/files/hardware/butt-weld-reducers/bw-reducer-concentric-nps4x2-sch40.stl) — NPS 4 × 2 concentric reducer, Sch 40 each end, end-to-end 102 mm; drawn as a straight cone between the ends (transition shape not set by B16.9); square ends
- bw-reducer-eccentric-nps4x2-sch40: [STEP](https://xemstudio.com/files/hardware/butt-weld-reducers/bw-reducer-eccentric-nps4x2-sch40.step) · [STL](https://xemstudio.com/files/hardware/butt-weld-reducers/bw-reducer-eccentric-nps4x2-sch40.stl) — NPS 4 × 2 eccentric reducer, Sch 40 each end, end-to-end 102 mm; drawn as a straight cone between the ends (transition shape not set by B16.9); square ends

## Questions

**How long is a 4 × 2 butt-weld reducer?**

102 mm end to end, concentric or eccentric.

**How long is a 2 × 1 butt-weld reducer?**

76 mm end to end.

## Fits with

- [Butt-weld elbows, 90° and 45° long radius (ASME B16.9), NPS ½ to 12](https://xemstudio.com/objects/butt-weld-elbows-long-radius/)
- [Butt-weld equal tees (ASME B16.9), NPS ½ to 12](https://xemstudio.com/objects/butt-weld-equal-tees/)
- [Schedule 40 pipe and PVC fittings, 1/2 to 2 inch](https://xemstudio.com/objects/schedule-40-pipe/)
- [Sanitary clamp reducers, concentric and eccentric, ½ to 4 in (tri-clamp style, BPE)](https://xemstudio.com/objects/sanitary-clamp-reducers/)