How Does Ansi B16 9 Fittings Work?

What are some of the most common components a pipe-fitter might use when welding? Buttwelded fittings, of course. But have you ever wondered why it’s usually so easy to find fittings that work?

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When it comes to factory-made buttwelding fittings, there are specific standards that need to be met during manufacturing. The most popular are ANSI and ASME. Let’s take a look at the ASME B 16.9 standard and how it differs from the ANSI standard.

The ASME B 16.9: Factory-Made Wrought Buttwelding Fittings

The ASME B 16.9 is set by the American Society of Mechanical Engineers. B 16.9 refers to factory-made buttwelding fittings. ASME B 16.9 governs scope, pressure ratings, size, marking, material, fitting dimensions, surface contours, end preparation, design proof tests, production tests, and tolerances. This standardization ensures that fittings are produced as they should be to scope and specifications, making it easier to integrate new parts to existing parts, and ensuring safety, strength, and stability.

Buttwelding can be an automated or by-hand process, used to attach pieces of metal together. Wrought buttwelding fittings are generally fairly simple; they are designed so that they can be welded directly onto another fitting. With that in mind, however, they need to be developed to certain standards, so they can correctly fit onto other fittings. Types of buttweld fitting can include elbows, caps, tees, reducers, and outlets.

Because buttwelding is one of the most common welding techniques and joining techniques, mechanical engineers are likely to be using and working with factory-made wrought buttweld fittings fairly frequently. Manufacturers of buttweld fittings will need to concern themselves with standards and specifications.

The ANSI vs ASME Standards

The ANSI vs ASME standards for some factory-made parts can vary. So, engineers may want to know whether they’re working to ANSI or ASME standards, as ASME standards are generally more specific and ANSI standards may be more encompassing. ASME is a standard that has been defining pipefitting since the early s. For most applications, following ASME standards will also follow ANSI standards.

ANSI is set by the American National Standards Institute. ANSI governs a very large variety of industries, while ASME is specifically designed for boilers, pressure vessels, and other similar areas. So, while something might meet ANSI standards, it may not meet ASME standards; ASME standards may be far more specific or rigorous. When it comes to the B16.9 standard, however, the ANSI and ASME standards are more likely to be similar.

Contact us to discuss your requirements of Ansi B16 9 Fittings. Our experienced sales team can help you identify the options that best suit your needs.

Standards and regulations are always important, especially in something as high-pressure as pipefittings and boilers. Because standards may also change, it’s important for organizations to dedicate some amount of time to update themselves on changes and additions. At Steel Forgings, we are always working to ensure that our pieces meet all required standards — and that they go above and beyond in terms of quality and consistency.

Scope, Codes & Pressure Ratings

The ASME B16.9 standard covers all dimensions, tolerances, ratings, testing, and marking for factory-made wrought butt-welding fittings in sizes NPS 1/2 through NPS 48 [DN 15 through DN ]. It 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 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, and . 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.

The butt welding fittings shall be manufactured by a “wrought” process denoting that fittings made of pipe, tubing, plate, or forging. The fittings can be made from a hot forming or cold forming process, in welded or seamless pipe. It may be a standard fitting that meets all dimensional requirements of ASME B16.9; It may be a special fitting in conformance with ASME B16.9, except that dimensional requirements are as agreed between purchaser and manufacturer.

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Dimensions & Tolerances

ASME B16.9 Butt Welding Fittings Elbow L/RReducing ElbowReturn L/R Elbow S/RReturn S/R3D Elbow Tee & CrossReducing TeeReducing Cross Stub EndCapReducer End BevelToleranceWall Thickness