ASME B16.9 is the standard for factory-made wrought butt-welding pipe fittings in sizes 1/2" through 48". Eathu provides all kind of butt welding pipe fittings in both carbon steel and stainless steel material. The tolorances for ASME B16.9 butt welding pipe fittings as below:

All Fittings [Note(1) and (2)] | Center-to-End Dimensions | Overall Length of Reducers and Lap Joint Stub Ends, F,H | Overall Length of Caps, E | 180-deg Returns |
NPS | DN | Outside Diameter at Bevel ,D[Notes(3) and (4)] | Inside Diameter at End | 90/45deg Long/Short Radius Elbow and Tee. | 3D Radius | Center-to-Center Dimension ,O | Back-to-Face Dimension ,K | Alignment of Ends,U |
[Notes(3) and (5)] | A,B,C,M | Elbows,A,B |
1/2to2 1/2 | 15-65 | +1.6-0.8 | 0.8 | 2 | 3 | 2 | 3 | 6 | 6 | 1 |
3to3 1/2 | 80-90 | 1.6 | 1.6 | 2 | 3 | 2 | 3 | 6 | 6 | 1 |
4 | 100 | 1.6 | 1.6 | 2 | 3 | 2 | 3 | 6 | 6 | 1 |
5to8 | 125-200 | +2.4 -1.6 | 1.6 | 2 | 3 | 2 | 6 | 6 | 6 | 1 |
10to18 | 250-450 | +4.0 -3.2 | 3.2 | 2 | 3 | 2 | 6 | 10 | 6 | 2 |
20to24 | 500-600 | +6.4 -4.8 | 4.8 | 2 | 3 | 2 | 6 | 10 | 6 | 2 |
26to30 | 650-750 | +6.4 -4.8 | 4.8 | 3 | 6 | 5 | 10 | ... | ... | ... |
32to48 | 800-1200 | +6.4 -4.8 | 4.8 | 5 | 6 | 5 | 10 | ... | ... | ... |
NPS | DN | Center-to-End Diamensions | NPS | DN | Angularity Tolerance |
Outside Diameter of Lap, G | Fillet Radius of Lap, R | Lap | Off Angle, Q | Off Plane, P |
Thickness |
1/2to2 1/2 | 15-65 | +0,-1 | +0,-1 | +1.6,-0 | 1/2to4 | 15-100 | 1 | 2 |
3to3 1/2 | 80-90 | +0,-1 | +0,-1 | +1.6,-0 | 5to8 | 125-200 | 2 | 4 |
4 | 100 | +0,-1 | +0,-2 | +1.6,-0 | 10to12 | 250-300 | 3 | 5 |
5to8 | 125-200 | +0,-1 | +0,-2 | +1.6,-0 | 14to16 | 350-400 | 3 | 6 |
10t018 | 250-450 | +0,-2 | +0,-2 | +3.2,-0 | 18to24 | 450-600 | 4 | `10 |
20to24 | 500-600 | +0,-2 | +0,-2 | +3.2,-0 | 26to30 | 650-750 | 5 | 10 |
26to30 | 650-750 | ... | ... | ... | 32to42 | 800-1050 | 5 | 13 |
32to48 | 800-1200 | ... | ... | ... | 44to48 | 1100-1200 | 5 | 19 |
a) All dimensions are in mm.
b) Tolerances are equal plus and minus except as noted.
Notes:
1) The inside diameter and the nominal wall thicknesses at ends are to be specified by the purchaser.
2) A minimum wall thickness of 87.5% applies unless the purchaser specifies a different wall thickness tolerance.
3) Out-of-round is the sum of absolute values of plus and minus tolerances.
4) This tolerance may not apply in localized areas of formed fittings where increased wall thckness is required to meet design requirements of ASME B16.9 para 2.2
5) 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.
check dimension and material information for butt welding pipe fittings

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