Ansi Buttweld Fittings – Dimensional Tolerances

CROSS-SECTIONAL TOLERANCES FOR ALL BUTTWELDING FITTINGS (ASME/ANSI B16.9 AND B16.28):

Nominal Pipe Size (NPS)	All Fittings
	OD at Bevel		ID at Bevel ±		Wall thickness
	in	mm	in	mm
½ to 2½	+0.06, -0.03	+1.6, -0.8	0.03	0.8	Not less than 87.5% of nominal wall thickness
3 to 3½	±0.6	±1.6	0.06	1.6
4	±0.6	±1.6	0.06	1.6
5 to 6	+0.09, -0.06	+2.4, -1.6	0.06	1.6
8	+0.09, -0.06	+2.4, -1.6	0.06	1.6
10	+0.16, -0.12	+4.0, -3.2	0.12	3.2
12 to 18	+0.16, -0.12	+4.0, -3.2	0.12	3.2
20 to 24	+0.25, -0.19	+6.4, -4.8	0.19	4.8
26 to 30	+0.25, -0.19	+6.4, -4.8	0.19	4.8
32 to 48	+0.25, -0.19	+6.4, -4.8	0.19	4.8

DIMENSIONAL TOLERANCES FOR ELBOWS AND RETURNS (ASME/ANSI B16.9 & B16.28):

Nominal Pipe Size (NPS)	90° & 45° Long Radius Elbows 90° Short Radius Elbows and Tees		180° Returns
	Centre-to-End Dimension ± A, B		Centre-to-Centre Dimension ± B (=2 x A)		Back-to-Face Dimension ± C
	in	mm	in	mm	in	mm
½ to 2½	0.06	2	0.25	6	0.25	6
3 to 3½	0.06	2	0.25	6	0.25	6
4	0.06	2	0.25	6	0.25	6
5 to 6	0.06	2	0.25	6	0.25	6
8	0.06	2	0.25	6	0.25	6
10	0.09	2	0.38	10	0.25	6
12 to 18	0.09	2	0.38	10	0.25	6
20 to 24	0.09	2	0.38	10	0.25	6
26 to 30	0.12	3	–	–	–	–
32 to 48	0.19	5	–	–	–	–

DIMENSIONAL TOLERANCES FOR REDUCERS, CAPS AND STUB ENDS (ASME/ANSI B16.9):

Nominal Pipe Size (NPS)	Reducers & Lap Joint Stub Ends		Caps		Lap Joint Stub Ends
	Overall Length ± A		Overall Length ± A		OD of Lap B		Fillet Radius of Lap B
	in	mm	in	mm	in	mm	in	mm
½ to 2½	0.06	2	0.12	3	+0	+0, -1	+0	+0, -1
3 to 3½	0.06	2	0.12	3	+0, -0.03	+0, -1	+0, -0.03	+0, -1
4	0.06	2	0.12	3	+0, -0.03	+0, -1	+0, -0.06	+0, -2
5 to 6	0.06	2	0.25	6	+0, -0.03	+0, -1	+0, -0.06	+0, -2
8	0.06	2	0.25	6	+0, -0.03	+0, -1	+0, -0.06	+0, -2
10	0.09	2	0.25	6	+0, -0.06	+0, -2	+0, -0.06	+0, -2
12 to 18	0.09	2	0.25	6	+0, -0.06	+0, -2	+0, -0.06	+0, -2
20 to 24	0.09	2	0.25	6	+0, -0.06	+0, -2	+0, -0.06	+0, -2
26 to 30	0.19	5	0.38	10	–	–	–	–
32 to 48	0.19	5	0.38	10	–	–	–	–

ALIGNMENT TOLERANCES (ASME/ANSI B16.9):

Alignment tolerances are concerned with the way that the ends of a fitting are cut. Exaggerated distortions are shown for clarity in the diagram below.

Nominal Pipe Size (NPS)	Off Plane Tolerances, ± A		Off Angle Tolerances, ± B		Alignment of Ends, ± C
	in	mm	in	mm	in	mm
½ to 4	0.06	2	0.03	1	0.03	1
5 to 8	0.12	4	0.06	2	0.03	1
10 to 12	0.19	5	0.09	2	0.06	2
14 to 16	0.25	6	0.09	3	0.06	2
18 to 24	0.38	10	0.12	4	0.06	2
26 to 30	0.38	10	0.19	5	–	–
32 to 42	0.50	13	0.19	5	–	–
44 to 48	0.75	19	0.19	5	–	–

Dimensional Tolerances for reducers, caps and stub ends (ASME/ANSI B16.9)

DIMENSIONS AND TOLERANCES MSS SP-43:

MSS SP-43 only covers buttweld fittings made for use with Schedule 5S and 10S pipe as defined in ANSI/ASME B36.19M (plus short pattern stub ends suitable for use with Schedule 40S pipe). The dimensions and tolerances defined in MSS SP-43 are substantially the same as those in ASME/ANSI specifications (½ to 24 in).

• MSS SP-43 tolerances (including alignment tolerance) are the same as for ASME/ANSI B16.9 and B16.28 except with regard to the outside diameter at the bevel:

• Tolerance of OD at Bevel =

± 0.03 in for NPS ½ to 4

+0.06, -0.03 in for NPS 5 to 8

+0.09, -0.03 in for NPS 10 to 18

+0.12, to -0.03 in for NPS 20 to 24

BUTTWELD FITTINGS AVAILABLE MATERIALS AND GRADES

• Inconel 625 Buttweld Fittings
• Inconel 660 Buttweld Fittings
• Inconel 690 Buttweld Fittings
• Inconel 718 Buttweld Fittings
• Inconel 825 Buttweld Fittings
• Inconel 800 Buttweld Fittings
• Titanium Grade 2 Buttweld Fittings
• Titanium Grade 5 Buttweld Fittings
• Duplex S31803 Buttweld Fittings
• Duplex S32205 Buttweld Fittings
• Super duplex S32520 Buttweld Fittings
• Super duplex S32750 Buttweld Fittings
• Hastelloy C22 Buttweld Fittings
• Hastelloy C276 Buttweld Fittings
• Monel 400 Buttweld Fittings
• Monel K500 Buttweld Fittings
• Stainless Steel 316TI Buttweld Fittings
• Stainless Steel 904L Buttweld Fittings
• Copper nickel 90/10 Buttweld Fittings
• Copper nickel 70/30 Buttweld Fittings
• Alloy 20 Buttweld Fittings
• Nickel 200 Buttweld Fittings
• Nickel 201 Buttweld Fittings