Tolerance For butt Welding Fittings

Butt-welding is the process of joining two pieces of material together along a single edge in a single plane. This process can be used on many types of materials, though metal and thermoplastics are the most common. When two sheets of steel are laid side-by-side and joined together along a single joint, this is an example of butt-welding.

Tolerances are in millimeters. mm

ASME / ANSI B16.9
All Fittings				90, 45 Elbows and Tees	Reducers	Caps	180?/span> Returns			Angularity Tolerance
Nominal Pipe Size	Outside Diameter at Bevel	Inside Diameter at End	Wall Thickness	Center to End Dimension	Overall Length	Overall Length	Center to Center Dimension	Back to face Dimension	Alignment of Ends	Nominal Pipe Size	off Angle	off Plane
(in)	D		t	A.B.C.M	H	E	O	K	U	(in)	Q	P
1/2to 21/2	+1.52-0.76	0.76	Not Less Than 87.5% of Nominal Thickness	1.52	1.52	3.05	6.35	6.35	0.76	1/2 to 4	0.76	1.51
3 to 31/2	1.52	1.52		1.52	1.52	3.05	6.35	6.35	0.75	5 to 8	1.52	3.05
4	1.52	1.52		1.52	1.52	3.05	6.35	6.36	0.76	10 to 12	2.29	4.83
5 to 8	+2.29-1.52	1.52		1.52	1.52	6.35	6.35	6.35	0.76	14 to 16	2.29	6.35
10 to 18	+4.06-3.05	3.05		2.29	2.29	6.35	9.65	6.35	1.52	18 to 24	3.05	9.65
20 to 24	+6.35-4.83	4.83		2.29	2.29	6.35	9.65	6.35	1.52	26 to 30	4.83	9.65
26 to 30	+6.35-4.83	4.83		3.05	4.83	9.65	-	-	-	32 to 36	4.83	12.7
32 to 36	+6.35-4.83	4.83		4.83	4.83	9.65	-	-	-