There are two kinds of reducers, concentric ones and eccentric ones. Concentric reducers maintain same center line for larger and smaller pipe while eccentric reducers maintain one face of both pipes in single plane. ASME B16.9 Table 11 provides dimensions of concentric and eccentric elbows for size range ¾” x 3/8” to 48” x 46”. This page provides metric dimensions for buttweld reducers.
Available Dimensions are: OD1 | Outside Diameter at Bevel – Large End, OD2 | Outside Diameter at Bevel – Small End, H | End to End Dimension.
| NPS1 | NPS2 | OD1 | OD2 | H |
|---|---|---|---|---|
| 3/4 | 1/2 | 26.7 | 21.3 | 38 |
| 3/4 | 3/8 | 26.7 | 17.3 | 38 |
| 1 | 3/4 | 33.4 | 26.7 | 51 |
| 1 | 1/2 | 33.4 | 21.3 | 51 |
| 1-1/4 | 1 | 42.2 | 33.4 | 51 |
| 1-1/4 | 3/4 | 42.2 | 26.7 | 51 |
| 1-1/4 | 1/2 | 42.2 | 21.3 | 51 |
| 1-1/2 | 1-1/4 | 48.3 | 42.2 | 64 |
| 1-1/2 | 1 | 48.3 | 33.4 | 64 |
| 1-1/2 | 3/4 | 48.3 | 26.7 | 64 |
| 1-1/2 | 1/2 | 48.3 | 21.3 | 64 |
| 2 | 1-1/2 | 60.3 | 48.3 | 76 |
| 2 | 1-1/4 | 60.3 | 42.2 | 76 |
| 2 | 1 | 60.3 | 33.4 | 76 |
| 2 | 3/4 | 60.3 | 26.7 | 76 |
| 2-1/2 | 2 | 73.0 | 60.3 | 89 |
| 2-1/2 | 1-1/2 | 73.0 | 48.3 | 89 |
| 2-1/2 | 1-1/4 | 73.0 | 42.2 | 89 |
| 2-1/2 | 1 | 73.0 | 33.4 | 89 |
| 3 | 2-1/2 | 88.9 | 73.0 | 89 |
| 3 | 2 | 88.9 | 60.3 | 89 |
| 3 | 1-1/2 | 88.9 | 48.3 | 89 |
| 3 | 1-1/4 | 88.9 | 42.2 | 89 |
| 3-1/2 | 3 | 101.6 | 88.9 | 102 |
| 3-1/2 | 2-1/2 | 101.6 | 73.0 | 102 |
| 3-1/2 | 2 | 101.6 | 60.3 | 102 |
| 3-1/2 | 1-1/2 | 101.6 | 48.3 | 102 |
| 3-1/2 | 1-1/4 | 101.6 | 42.2 | 102 |
| 4 | 3-1/2 | 114.3 | 101.6 | 102 |
| 4 | 3 | 114.3 | 88.9 | 102 |
| 4 | 2-1/2 | 114.3 | 73.0 | 102 |
| 4 | 2 | 114.3 | 60.3 | 102 |
| 4 | 1-1/2 | 114.3 | 48.3 | 102 |
| 5 | 4 | 141.3 | 114.3 | 127 |
| 5 | 3-1/2 | 141.3 | 101.6 | 127 |
| 5 | 3 | 141.3 | 88.9 | 127 |
| 5 | 2-1/2 | 141.3 | 73.0 | 127 |
| 5 | 2 | 141.3 | 60.3 | 127 |
| 6 | 5 | 168.3 | 141.3 | 140 |
| 6 | 4 | 168.3 | 114.3 | 140 |
| 6 | 3-1/2 | 168.3 | 101.6 | 140 |
| 6 | 3 | 168.3 | 88.9 | 140 |
| 6 | 2-1/2 | 168.3 | 73.0 | 140 |
| 8 | 6 | 219.1 | 168.3 | 152 |
| 8 | 5 | 219.1 | 141.3 | 152 |
| 8 | 4 | 219.1 | 114.3 | 152 |
| 8 | 3-1/2 | 219.1 | 101.6 | 152 |
| 10 | 8 | 273.0 | 219.1 | 178 |
| 10 | 6 | 273.0 | 168.3 | 178 |
| 10 | 5 | 273.0 | 141.3 | 178 |
| 10 | 4 | 273.0 | 114.3 | 178 |
| 12 | 10 | 323.8 | 273.0 | 203 |
| 12 | 8 | 323.8 | 219.1 | 203 |
| 12 | 6 | 323.8 | 168.3 | 203 |
| 12 | 5 | 323.8 | 141.3 | 203 |
| 14 | 12 | 355.6 | 323.8 | 330 |
| 14 | 10 | 355.6 | 273.0 | 330 |
| 14 | 8 | 355.6 | 219.1 | 330 |
| 14 | 6 | 355.6 | 168.3 | 330 |
| 16 | 14 | 406.4 | 355.6 | 356 |
| 16 | 12 | 406.4 | 323.8 | 356 |
| 16 | 10 | 406.4 | 273.0 | 356 |
| 16 | 8 | 406.4 | 219.1 | 356 |
| 18 | 16 | 457.0 | 406.4 | 381 |
| 18 | 14 | 457.0 | 355.6 | 381 |
| 18 | 12 | 457.0 | 323.8 | 381 |
| 18 | 10 | 457.0 | 273.0 | 381 |
| 20 | 18 | 508.0 | 457.0 | 508 |
| 20 | 16 | 508.0 | 406.4 | 508 |
| 20 | 14 | 508.0 | 355.6 | 508 |
| 20 | 12 | 508.0 | 323.8 | 508 |
| 22 | 20 | 559.0 | 508.0 | 508 |
| 22 | 18 | 559.0 | 457.0 | 508 |
| 22 | 16 | 559.0 | 406.4 | 508 |
| 22 | 14 | 559.0 | 355.4 | 508 |
| 24 | 22 | 610.0 | 559.0 | 508 |
| 24 | 20 | 610.0 | 508.0 | 508 |
| 24 | 18 | 610.0 | 457.0 | 508 |
| 24 | 16 | 610.0 | 406.4 | 508 |
| 26 | 24 | 660.0 | 610.0 | 610 |
| 26 | 22 | 660.0 | 559.0 | 610 |
| 26 | 20 | 660.0 | 508.0 | 610 |
| 26 | 18 | 660.0 | 457.0 | 610 |
| 28 | 26 | 711.0 | 660.0 | 610 |
| 28 | 24 | 711.0 | 610.0 | 610 |
| 28 | 20 | 711.0 | 508.0 | 610 |
| 28 | 18 | 711.0 | 457.0 | 610 |
| 30 | 28 | 762.0 | 711.0 | 610 |
| 30 | 26 | 762.0 | 660.0 | 610 |
| 30 | 24 | 762.0 | 610.0 | 610 |
| 30 | 20 | 762.0 | 508.0 | 610 |
| 32 | 30 | 813.0 | 762.0 | 610 |
| 32 | 28 | 813.0 | 711.0 | 610 |
| 32 | 26 | 813.0 | 660.0 | 610 |
| 32 | 24 | 813.0 | 610.0 | 610 |
| 34 | 32 | 864.0 | 813.0 | 610 |
| 34 | 30 | 864.0 | 762.0 | 610 |
| 34 | 26 | 864.0 | 660.0 | 610 |
| 34 | 24 | 864.0 | 610.0 | 610 |
| 36 | 34 | 914.0 | 864.0 | 610 |
| 36 | 32 | 914.0 | 813.0 | 610 |
| 36 | 30 | 914.0 | 762.0 | 610 |
| 36 | 26 | 914.0 | 660.0 | 610 |
| 36 | 24 | 914.0 | 610.0 | 610 |
| 38 | 36 | 965.0 | 914.0 | 610 |
| 38 | 34 | 965.0 | 864.0 | 610 |
| 38 | 32 | 965.0 | 813.0 | 610 |
| 38 | 30 | 965.0 | 762.0 | 610 |
| 38 | 28 | 965.0 | 711.0 | 610 |
| 38 | 26 | 965.0 | 660.0 | 610 |
| 40 | 38 | 1016.0 | 965.0 | 610 |
| 40 | 36 | 1016.0 | 914.0 | 610 |
| 40 | 34 | 1016.0 | 864.0 | 610 |
| 40 | 32 | 1016.0 | 813.0 | 610 |
| 40 | 30 | 1016.0 | 762.0 | 610 |
| 42 | 40 | 1067.0 | 1016.0 | 610 |
| 42 | 38 | 1067.0 | 965.0 | 610 |
| 42 | 36 | 1067.0 | 914.0 | 610 |
| 42 | 34 | 1067.0 | 864.0 | 610 |
| 42 | 32 | 1067.0 | 813.0 | 610 |
| 42 | 30 | 1067.0 | 762.0 | 610 |
| 44 | 42 | 1118.0 | 1067.0 | 610 |
| 44 | 40 | 1118.0 | 1016.0 | 610 |
| 44 | 38 | 1118.0 | 965.0 | 610 |
| 44 | 36 | 1118.0 | 914.0 | 610 |
| 46 | 44 | 1168.0 | 1118.0 | 711 |
| 46 | 42 | 1168.0 | 1067.0 | 711 |
| 46 | 40 | 1168.0 | 1016.0 | 711 |
| 46 | 38 | 1168.0 | 965.0 | 711 |
| 48 | 46 | 1219.0 | 1168.0 | 711 |
| 48 | 44 | 1219.0 | 1118.0 | 711 |
| 48 | 42 | 1219.0 | 1067.0 | 711 |
| 48 | 40 | 1219.0 | 1016.0 | 711 |
| NPS1 | NPS2 | OD1 | OD2 | H |
GENERAL NOTES:
(a) All dimensions are in millimeters.
(b) While the figure illustrates a bell-shaped reducer, the use of a conical reducer is not prohibited.
