Concentric Pipe Reducer and Eccentric Pipe Reducer Dimensions are covered in ASME B16.9. Refer to the table given below for the size 1/2″ to 24″.

concentric reducer and eccentric reducer dimensions
NOMINAL PIPE SIZE OUTSIDE DIAMETER END TO END
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
All Dimensions are in mm

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Pipe Fittings Dimensions Tolerance as per ASME B16.9

Dimension Tolerance for Concentric and Eccentric Reducer
NOMINAL PIPE SIZE ALL FITTINGS ALL FITTINGS ALL FITTINGS ELBOWS AND TEES 180 DEG RETURN BENDS 180 DEG RETURN BENDS 180 DEG RETURN BENDS REDUCERS CAPS
NPS O.D. at Bevel (1), (2) I.D. at End
(1), (3), (4) 		Wall Thickness (3) Centre-to-End Dimension A,B,C,M Centre-to-Centre O Back-to-Face K Alignment of Ends U Overall Length H Overall Length E
½ to 2½ 0.06
-0.03 		0.03 Not less than 87.5% of nominal thickness 0.06 0.25 0.25 0.03 0.06 0.12
3 to 3 ½ 0.06 0.06 0.06 0.25 0.25 0.03 0.06 0.12
4 0.06 0.06 0.06 0.25 0.25 0.03 0.06 0.12
5 to 8 0.09
-0.06 		0.06 0.06 0.25 0.25 0.03 0.06 0.25
10 to 18 0.16
-0.12 		0.12 0.09 0.38 0.25 0.06 0.09 0.25
20 to 24 0.25
-0.19 		0.19 0.09 0.38 0.25 0.06 0.09 0.25
26 to 30 0.25
-0.19 		0.19 0.12 … … … 0.19 0.38
32 to 48 0.25
-0.19 		0.19 0.19 … … … 0.19 0.38
NOMINAL PIPE SIZE NPS ANGULARITY TOLERANCES ANGULARITY TOLERANCES ALL DIMENSIONS ARE GIVEN IN INCHES. TOLERANCES ARE EQUAL PLUS AND MINUS EXCEPT AS NOTED.
Off Angle Q Off Plane P (1) Out-of-round is the sum of absolute values of plus and minus tolerance.
(2) This tolerance may not apply in localized areas of formed fittings where increased wall thickness is required to meet design requirements of ASME B16.9.
(3) The inside diameter and the nominal wall thicknesses at ends are to be specified by the purchaser.
(4) Unless otherwise specified by the purchaser, these tolerances apply to the nominal inside diameter, which equals the difference between the nominal outside diameter and twice the nominal wall thickness.
½ to 4 0.03 0.06
5 to 8 0.06 0.12
10 to 12 0.09 0.19
14 to 16 0.09 0.25
18 to 24 0.12 0.38
26 to 30 0.19 0.38
32 to 42 0.19 0.50
44 to 48 0.18 0.75

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About Author

Varun Patel, B.E – Mechanical, PMP®

19+ years of experience in the oil and gas sector, specializing in project management, contracts, project control, project coordination, QA/QC and inspection of large-scale Greenfield and Brownfield Projects such as Refinery, Petrochemical, Wellhead production, and Process platform. Proven track record of delivering large-scale projects while ensuring adherence to safety and quality standards. Skilled in leading and mentoring cross-functional teams and resolving technical issues to achieve successful project outcomes.