ASME B16.9 standard specification

ASME B16.9 Standard covers overall dimensions, tolerances,ratings, testing, and markings for factory-made wrought butt-welding fittings in sizes NPS 1⁄2 through NPS 48 (DN 15 through DN 1200).

Scope

1.1 General
This Standard covers overall dimensions, tolerances,ratings, testing, and markings for factory-made wrought buttwelding fittings in sizes NPS 1⁄2 through NPS 48 (DN 15 through DN 1200).

1.2 Special Fittings

Fittings may be made to special dimensions, sizes,shapes, and tolerances by agreement between the manufacturer and the purchaser.
1.3 Fabricated Fittings

Fabricated laterals and other fittings employing circumferential or intersection welds are considered pipe fabrication and are not within the scope of this Standard.

Fabricated lap joint stub ends are exempt from the above restrictions, provided they meet all the requirements of the applicable ASTM material specification listed in section 5.

1.4 Standard Units

The values stated in either metric or U.S. Customary units are to be regarded separately as standard. Within the text, the U.S. Customary units are shown in parentheses.The values stated in each system are not exact equivalents; therefore, each system must be used independently of the other. Combining values from the two systems may result in nonconformance with this Standard.
The designation for size is NPS for both metric- and customary-dimensioned fittings. Fitting pressure rating is associated with the connecting wall thickness of pipe of equivalent size and material.

1.5 References

1.5.1 Referenced Standards. Standards and specifications adopted by reference in this Standard are shown in Mandatory Appendix II. It is not considered practical to identify the specific edition of each standard and specification in the individual references. Instead, the specific edition reference is identified in Mandatory Appendix II. A product made in conformance with a prior edition of referenced standards and in all other respects conforming to this Standard will be considered to be in conformance.

1.5.2 Codes and Regulations. A fitting used under the jurisdiction of the ASME Boiler and Pressure Vessel Code, the ASME Code for Pressure Piping, or a governmental regulation is subject to any limitation of that code or regulation. This includes any maximum temperature

limitation, or rule governing the use of a material at low temperature.

1.6 Service Conditions
Criteria for selection of fitting types and materials suitable for particular fluid service are not within the scope of this Standard.

1.7 Welding

Installation welding requirements are outside the scope of this Standard.

1.8 Quality Systems

Nonmandatory requirements relating to the fitting manufacturer’s Quality System Program are described in Nonmandatory Appendix A.

1.9 Convention

For the purpose of determining conformance with this Standard, the convention for fixing significant digits where limits (maximum or minimum values) are specified shall be rounded off as defined in ASTM E 29. This requires that an observed or calculated value shall be rounded off to the nearest unit in the last righthand digit used in expressing the limit. Decimal values and tolerances do not imply a particular method of measurement.

1.10 Pressure Rating Designation
Class, followed by a dimensionless number, is the designation for pressure–temperature ratings. Standardized designations for flanges per ASME B16.5 referenced in this Standard are Classes 150, 300, 600, 900, 1500,and 2500.

Pipe Fittings Dimensions Tolerance as per ASME B16.9

Sizes 1/2″ – 48″

ASME / ANSI B16.9 dimension

Nominal Pipe Size	Outside Diameter		90° Elbows		45° Elbows		180° Returns
(inches)	(mm)	(inches)	Long Radius	Short Radius	Long Radius		Long Radius
			Center to Face(inches)	Center to Face(inches)	Center to Face(inches)	Radius(inches)	Center to Center(inches)	Back to face(inches)
1/2	21.3	0.84	1.5	–	5/8		2	1.875
3/4	26.7	1.05	1.125	–	7/16		2.25	1.6875
1	33.4	1.315	1.5	1	7/8		3	2.1875
1.25	42.2	1.66	1.875	1.25	1		3.75	2.75
1.5	48.3	1.9	2.25	1.5	1.125	3	4.5	3.25
2	60.3	2.375	3	2	1.375	4	6	4.1875
2.5	73	2.875	3.75	2.5	1.75	5	7.5	5.1875
3	88.9	3.5	4.5	3	2	6	9	6.25
3.5	101.6	4	5.25	3.5	2.25	7	10.5	7.25
4	114.3	4.5	6	4	2.5	8	12	8.25
5	141.3	5.563	7.5	5	3.125	10	15	10.3125
6	168.3	6.625	9	6	3.75	12	18	12.3125
8	219.1	8.625	12	8	5	12	24	16.3125
10	273.1	10.75	15	10	6.25	15	30	20.375
12	323.9	12.75	18	12	7.5	18	36	24.375

Tolerances of welded fittings

NOMINAL PIPE SIZE NPS	ANGULARITY TOLERANCES	ANGULARITY TOLERANCES
Size	Off Angle Q	Off Plane P
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	0.5
44 to 48	0.18	0.75

All dimensions are given in inches. Tolerances are equal plus and minus except as noted.
Out-of-round is the sum of absolute values of plus and minus tolerance.
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.
The inside diameter and the nominal wall thicknesses at ends are to be specified by the purchaser.
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.