During the inspection of the stub end dimensions, you have to check for the following things;

  • Stub diameter – Both Lap and hub
  • Length
  • Thickness
  • The radius of the lap to stub hub

Refer to the table given below for the Stub end dimensions as per ASME B16.9

Stub End Dimensions

NOMINAL PIPE SIZE LAP DIAMETER OUTSIDE DIAMETER LONG PATTERN LENGTH SHORT PATTERN LENGTH RADIUS
Inch. A OD Min OD Max L L R
1/2 35 22.8 20.5 76 51 3
3/4 43 28.1 25.9 76 51 3
1 51 35 32.6 102 51 3
1 1/4 64 43.6 41.4 102 51 5
1 1/2 73 49.9 47.5 102 51 6
2 92 62.4 59.5 152 64 8
2 1/2 105 75.3 72.2 152 64 8
3 127 91.3 88.1 152 64 10
3 1/2 140 104 100.8 152 76 10
4 157 116.7 113.5 152 76 11
5 186 144.3 140.5 203 76 11
6 216 171.3 167.5 203 89 13
8 270 222.1 218.3 203 102 13
10 324 277.2 272.3 254 127 13
12 381 328 323.1 254 152 13
14 413 359.9 354.8 305 152 13
16 470 411 405.6 305 152 13
18 533 462 456 305 152 13
20 584 514 507 305 152 13
22 641 565 558 305 152 13
24 692 616 609 305 152 13

All dimensions are in mm.

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Pipe Fittings Dimensions Tolerance as per ASME B16.9

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.