1. General Tolerances for All Fittings of ASME B16.9

NPS	DN	O.D	I.D	Off Angle, Q	Off Plane, P
1/2~2-1/2	15~65	+1.6, -0.8	±0.8	±1	±2
3~3-1/2	80~90	±1.6	±1.6	±2	±4
4	100	±1.6	±1.6	±3	±5
5~8	125~200	+2.4, -1.6	±1.6	±3	±6
10~18	250~450	+4.0, -3.2	±3.2	±4	±10
20~24	500~600	+6.4, -4.8	±4.8	±5	±10
26~30	650~750	+6.4, -4.8	±4.8	±5	±13
32~48	800~1200	+6.4, -4.8	±4.8	±5	±19

*All dimensions are in mm unit. NPS: Nominal Pipe Size; DN: Nominal Diameter.
*O.D: outside diameter at bevel; I.D: inside diameter at end; Both P & Q are angularity tolerances.
*A minimum wall thickness of 87.5% should apply unless otherwise specified by the purchaser.

2. Tolerances of Center-to-End & Overall Length Dimensions

NPS	DN	*I	*II	*III	*IV
1/2~2-1/2	15~65	±2	±3	±2	±3
3~3-1/2	80~90	±2	±3	±2	±3
4	100	±2	±3	±2	±3
5~8	125~200	±2	±3	±2	±6
10~18	250~450	±2	±3	±2	±6
20~24	500~600	±2	±3	±2	±6
26~30	650~750	±3	±6	±5	±10
32~48	800~1200	±5	±6	±5	±10

*All dimensions are in mm unit.
*I refers to the tolerances for center-to-end dimensions of 90° & 45° long and short radius elbows and tees, A, B, C, M.
*II refers to the tolerances for center-to-end dimensions of 3D radius elbows, A, B.
*III refers to the tolerances for overall length of reducers and lap joint stub ends, F, H.
*IV refers to the tolerances for overall length of caps, E.

3. Tolerances for 180° Returns & Lap Joint Stub Ends

NPS	DN	180° Return			Lap Joint Stub Ends
inch	mm	O	K	U	G	R	T
1/2~2-1/2	15~65	±6	±6	±1	+0, -1	+0, -1	+1.6, -0
3~3-1/2	80~90	±6	±6	±1	+0, -1	+0, -1	+1.6, -0
4	100	±6	±6	±1	+0, -1	+0, -2	+1.6, -0
5~8	125~200	±6	±6	±1	+0, -1	+0, -2	+1.6, -0
10~18	250~450	±10	±6	±2	+0, -2	+0, -2	+3.2, -0
20~24	500~600	±10	±6	±2	+0, -2	+0, -2	+3.2, -0

*All dimensions are in mm unit.
*O:center-to-center dimensions; K:back-to-face dimensions; U:alignment of ends.
*G:outside diameter of lap; R:fillet radius of lap; T:Lap thickness.

See more about the ASME B16.9 pipe fittings.