Standard reducer dimensions

Standard dimensions for piping reducers and expanders are recommended by ASME/ANSI standards.

Piping reducer

Piping reducers and expanders are tapered pipe joints used to join two pipes of different sizes together.

When the upstream pipe is larger in size, the joint is called a pipe reducer. As the flow goes from a large pipe to a 'reduced' pipe size.

Similarly, when the upstream pipe is smaller, flow goes from a small pipe to an 'expanded' pipe size. Hence in this case the tapered joint is called an 'expander' in this case.

Standard dimension calculator

You can use these calculators to quickly get standard dimensions for different sizes of piping reducers/expanders.

Standard reducer dimensions

Nominal Pipe Size

(inches)

Outside Diameter

(mm)

Length

(mm)

Inch D P H
3/4 x 1/2 26.7 21.3 38
3/4 x 3/8 26.7 17.1 38
1 x 3/4 33.4 26.7 51
1 x 1/2 33.4 21.3 51
1 1/4 x 1 42.2 33.4 51
1 1/4 x 3/4 42.2 26.7 51
1 1/4 x 1/2 42.2 21.3 51
1 1/2 x 1 1/2 48.3 42.2 64
1 1/2 x 1 48.3 33.4 64
1 1/2 x 3/4 48.3 26.7 64
1 1/2 x 1/2 48.3 21.3 64
2 x 1 1/2 60.3 48.2 76
2 x 1 1/4 60.3 42.2 76
2 x 1 60.3 33.4 76
2 x 3/4 60.3 26.7 76
2 1/2 x 2 73 60.3 89
2 1/2 x 1 1/2 73 48.3 89
2 1/2 x 1 1/4 73 42.2 89
2 1/2 x 1 73 33.4 89
3 x 2 1/2 88.9 73 89
3 x 2 88.9 60.3 89
3 x 1 1/2 88.9 48.3 89
3 x 1 1/4 88.9 42.2 89
3 1/2 x 3 101.6 88.9 102
3 1/2 x 21/2 101.6 73 102
3 1/2 x 2 101.6 60.3 102
3 1/2 x 1 1/2 101.6 48.3 102
3 1/2 x 1 1/4 101.6 42.2 102
4 x 3 1/2 114.3 101.6 102
4 x 3 114.3 88.9 102
4 x 2 1/2 114.3 73 102
4 x 2 114.3 60.3 102
4 x 1 1/2 114.3 48.3 102
5 x 4 141.3 114.3 127
5 x 3 1/2 141.3 101.6 127
5 x 3 141.3 88.9 127
5 x 2 1/2 141.3 73 127
5 x 2 141.3 60.3 127
6 x 5 168.3 141.3 140
6 x 4 168.3 114.3 140
6 x 3 1/2 168.3 101.6 140
6 x 3 168.3 88.9 140
6 x 2 1/2 168.3 73 140
8 x 6 219.1 168.3 152
8 x 5 219.1 141.3 152
8 x 4 219.1 114.3 152
8 x 3 1/2 219.1 101.6 152
10 x 8 273.1 219.1 178
10 x 6 273.1 168.1 178
10 x 5 273.1 141.3 178
10 x 4 273.1 114.3 178
12 x 10 323.9 273.1 203
12 x 8 323.9 219.1 203
12 x 6 323.9 168.3 203
12 x 5 323.9 141.3 203
14 x 12 355.6 323.9 330
14 x 10 355.6 273.1 330
14 x 8 355.6 219.1 330
14 x 6 355.6 168.3 330
16 x 14 406.4 355.6 356
16 x 12 406.4 323.9 356
16 x 10 406.4 273.1 356
16 x 8 406.4 219.1 356
16 x 6 406.4 168.3 356
18 x 16 457 406.4 381
18 x 14 457 355.6 381
18 x 12 457 323.9 381
18 x 10 457 273.1 381
18 x 8 457 219.1 381
20 x 18 508 457 508
20 x 16 508 406.4 508
20 x 14 508 355.6 508
20 x 12 508 323.9 508
20 x 10 508 273.1 508
20 x 8 508 219.1 508
22 x 20 559 508 508
22 x 18 559 457 508
22 x 16 559 406.4 508
22 x 14 559 355.6 508
22 x 12 559 323.9 508
24 x 10 559 273.1 508
24 x 22 610 559 508
24 x 20 610 508 508
24 x 18 610 457 508
24 x 16 610 406.4 508
24 x 14 610 355.6 508
24 x 12 610 323.9 508
24 x 10 610 273.1 508

Standards for piping reducers

B16.1 (2005) - Gray Iron Pipe Flanges and Flanged Fittings: Classes 25, 125, and 250

This Standard covers Classes 25, 125, and 250 Gray Iron Pipe Flanges and Flanged Fittings. It includes: (a) pressure-temperature ratings; (b) sizes and method of designating openings of reducing fittings; (c) markings; (d) materials; (e) dimensions and tolerances; (f) bolting and gaskets; (g) pressure testing.

B16.5 (2009) – Pipe flanges and flanged fittings (2009)

This standard covers pressure-temperature ratings, materials, dimensions, tolerances, marking, testing and methods of designating for pipe flanges and flanged fittings

Here are more ASME/ANSI piping standards for reference.