ASME/ANSI B16.9

ASME 16.9 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).

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ASME/ANSI B16.9 Pipe End Caps

ASME B16.9 also covers pipe fittings made to special dimensions, sizes, shapes, and tolerances by agreement between the manufacturer and the purchaser. Fabricated laterals, saddles, and other fittings employing circumferential or intersection welds are considered pipe fabrication other than ASME B16.9 fittings. However, fabricated lap joint stub ends are exempt from the above restrictions, provided they meet all the requirements of the applicable ASTM material specification.

The term “wrought” denotes fittings made of seamless or welded pipes, tubing, plates, or forgings. Metals-Piping supplies ASME B16.9 butt-welding pipe fittings in a comprehensive range of materials covering carbon steel, alloy steel, stainless steel and non-ferrous metals. These fittings include long radius elbows, reducing elbows, long radius returns, short radius elbows, short radius 180° returns, 3D elbows, straight tees, straight crosses, reducing tees, reducing crosses, lap joint stub ends, caps, concentric reducers, and eccentric reducers. All fittings supplied shall be free of imperfections such as dents, scratches, sharp intersections(corners), pits, and creases, etc.

ASME / ANSI B16.9 dimension

ASME B16.9 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).

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Nominal Outside Diameter 90° Elbows 45° Elbows 180° Returns
Pipe Size
Long Radius Short Radius Long Radius Long Radius
(inches) (mm) (inches) Center to Face Center to Face Center to Face Radius Center to Center Back to face
(inches) (inches) (inches) (inches) (inches) (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.

  1. Out-of-round is the sum of absolute values of plus and minus tolerance.
  2. 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.
  3. The inside diameter and the nominal wall thicknesses at ends are to be specified by the purchaser.
  4. 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.

The ASME B16.9 pipe fittings can be used under the jurisdiction of the ASME Boiler & Pressure Vessel Code (BPVC) as well as the ASME Code for pressure piping. Referencing pressure ratings of flanges per ASME B16.5, they can be designated as Classes 150, 300, 600, 900, 1500 and 2500. The allowable pressure ratings for ASME B16.9 pipe fittings may be calculated as for straight seamless pipe of equivalent material in accordance with the rules established in the applicable sections of ASME B31 Code for pressure piping.

Design of Fittings

The design of butt welding pipe fittings made to ASME B16.9 shall be established by one of the following methods: (a) mathematical analyses contained in pressure vessel or piping codes; (b) proof testing; (c) experimental stress analysis with hydrostatic testing to validate experimental results; (d) detailed stress analysis with results evaluation.

Standard Marking

Generally, ASME B16.9 pipe fittings shall be marked to show the following details: “trademark + material grade + wall thickness + size + heat number”. For example, “M ASTM A234 WP5 SCH80 6″ 385“. When steel stamps are used, care shall be taken so that
the marking is not deep enough or sharp enough to cause cracks or to reduce the wall thickness of the fitting below the minimum allowed.

Material & Manufacture

The ASME B16.9 fittings may be made from an extensive range of mateirals covering (1) carbon and low-alloy steels in accordance with ASTM A234 and ASTM A420; (2) austenitic and duplex stainless steels in accordance with ASTM A403 and ASTM A815; (3) nickel alloys in accordance with ASTM B366; (4) aluminum alloys in accordance with ASTM B361; and (5) titanium alloys in accordance with ASTM B363.

ASME B16.9

Pipe Fittings Dimensions Tolerance as per ASME B16.9:

Sizes 1/2″ – 48″

  • ASME / ANSI B16.9 Butt Weld Elbow – Long Radius
  • ASME / ANSI B16.9 Butt Weld Elbow – Short Radius
  • ASME / ANSI B16.9 Butt Weld Reducing Elbow
  • ASME / ANSI B16.9 Butt Weld 45° Elbow
  • ASME / ANSI B16.9 Butt Weld Fabricated Tee
  • ASME / ANSI B16.9 Butt Weld Reducer
  • ASME / ANSI B16.9 Butt Weld Concentric Reducer
  • ASME / ANSI B16.9 Butt Weld Eccentric Reducer
  • ASME / ANSI B16.9 Butt Weld 3D Elbow
  • ASME / ANSI B16.9 Butt Weld Stub Ends
  • ASME / ANSI B16.9 Butt Weld Cross
  • ASME / ANSI B16.9 Butt Weld Reducing Cross
  • ASME / ANSI B16.9 Butt Weld Tees
  • ASME / ANSI B16.9 Butt Weld End Cap
  • ASME / ANSI B16.9 Butt Weld Coupling
  • ASME / ANSI B16.9 Butt Weld Pipe Nipple
  • ASME / ANSI B16.9 Butt Weld 5D Elbow
  • ASME / ANSI B16.9 Butt Welded Pipe Fittings

【H】 Ceramic lined pipe

Ceramic lined pipe is made through self-propagating high-temperature synthesis (SHS) technique.

【H】 Cast basalt lined steel pipe

Cast basalt lined steel pipe is composed by lined with cast basalt pipe, outside steel pipe and cement mortar filling between the two layers.

【H】 Ceramic Tile Lined Pipes

Ceramic tile lined pipes have very uniform coating of specially formulated ceramic material that is affixed to the inner of the pipe.

【H】 Rare earth alloy wear-resistant pipe

The material of the rare earth alloy wear-resistant pipe is ZG40CrMnMoNiSiRe, which is also the grade of rare earth alloy steel.

【H】 Tubes Erosion Shields

Tubes Erosion Shields are used to protect boiler tubing from the highly erosive effects of high temperatures and pressures thereby greatly extending tube life.

【H】 ASTM A213 T91 Alloy Tube

The ASTM A213 T91 seamless tubes are primarily used for boiler, superheater, and heat-exchanger.