Standards · ASME and ASTM · ASME B16.9

ASME B16.9: Factory-made wrought buttwelding fittings

Overall dimensions, tolerances, ratings, testing and marking of buttwelding elbows, tees, reducers, caps and stub ends – the dimension standard – the steel comes from A234, A403 or A420.

Issued by: ASME
Edition (publisher, as of 2 October 2026): 2024
Dimension standard: Factory-made wrought buttwelding fittings
European counterpart: EN 10253-2 / EN 10253-4
Belongs with: ASTM A234/A234M · ASTM A403/A403M · ASTM A420/A420M · ASME B16.25 · ASME B36.10M
At Zickwolff: we carry – from stock or to order, lead time on request

Scope: sizes, classes, grades

NPS 1/2 to 48 (DN 15 to 1200), any wall thickness that can be made. Elbows 45°, 90° and 180° long radius (1.5 × NPS) and short radius (1 × NPS), 3D bends, equal and reducing tees, concentric and eccentric reducers, caps, lap-joint stub ends. Wall thickness follows the pipe schedule of B36.10M/B36.19M, the rating follows the pipe of the same wall.

Product form

Wrought (seamless or welded) from pipe, plate or forgings – not low-pressure corrosion-resistant fittings to MSS SP-43.

The European counterpart – and the limits of the comparison

EN 10253-2 (carbon and alloy steel) and EN 10253-4 (austenitic and austenitic-ferritic steel) are the European fittings standards with specific inspection requirements.

EN sizes by outside diameter × wall in mm, ASME by NPS and schedule – outside diameters agree only partly (26.9 vs 26.7, 33.7 vs 33.4, 42.4 vs 42.2, 323.9 vs 323.8 mm) and the wall series do not match. EN fittings carry the material designation of the pipe (P235GH, P265GH), ASME fittings a fitting grade (WPB). Weld bevel 37.5° versus 30°. Type A/B wall logic of EN 10253 has no ASME equivalent.

“To ASME” means three different things Dimensions to an ASME standard with a European material, dimensions plus an ASTM material, or a whole line designed to ASME B31. Under the Pressure Equipment Directive and the operating law these are not the same case – and the stamp on the part says nothing about the later inspection regime.

Marking on the part

Manufacturer, material grade with the letters WP (e.g. WPB, WP316L, WPL6), schedule or wall thickness, NPS, usually heat number – stainless fittings to MSS SP-43 instead with CR and the material symbol.

The standard family: dimensions, material, pipe

ASTM A234/A234M · ASTM A403/A403M · ASTM A420/A420M · ASME B16.25 · ASME B36.10M

At Zickwolff

Buttwelding fittings to B16.9 in A234 WPB, A403 WP304L/WP316L and A420 WPL6 are part of our range – elbows, tees, reducers and caps in the common schedules, from stock or to order. Dimension tables follow the pipe schedules.

Dimensions Dimension tables for this standard are available on request – we work from manufacturer catalogues, not from copied standard tables.

Frequently asked questions about ASME B16.9

What does "to ASME" mean on a part?

Three different things: dimensions to an ASME standard (B16.5, B16.9) with a European material (P265GH), dimensions plus an ASTM material (A105, A234 WPB), or a complete line designed to ASME B31.1/B31.3. Under the PED and the Betriebssicherheitsverordnung these are not the same – the stamp B16.9 says nothing about the later inspection regime.

Which wall thickness does a B16.9 fitting have?

The one you order: fittings are made to the pipe schedules of B36.10M/B36.19M (STD, XS, Sch 40, 80, 160, XXS) and are rated like pipe of the same wall. The minimum wall is 87.5 % of nominal.

Can I weld a B16.9 elbow to an EN 10253 pipe system?

Technically yes if outside diameter and wall match, which they rarely do exactly – and the bevel (37.5° vs 30°) must be prepared. For a PED line the ASTM material then needs an appraisal. Our advice: stay in one world per line.

Parts to ASME and ASTM – from one source

Tell us standard, size (NPS and schedule or Class), material grade, certificate and quantity – we check what is in stock, what we procure and which European part would do the same job.

Send an inquiry

Your inquiry to Zickwolff

Send us what you have – designation, standard, quantity, date. We will clarify the rest with you.

One item or a question

Send inquiry

Not in stock? We procure it – single items too.

Designation, standard and quantity are enough.

Several items

Send bill of materials

200 items? One parts list is enough – we deliver complete.

Attach it as a file.

Helpful if already known: project and country, date needed, certificates, packaging and language of the packing lists. If anything is missing, we will ask.

It is urgent

Request express

When do you need it? Express delivery, to the site if required.

Tell us by when you need the material – we will tell you what is possible.

← Back to ASME and ASTM standards

Basis: the publicly accessible scopes and abstracts of ASME and ASTM (editions as of 2 October 2026), manufacturer catalogues, a trade reference catalogue DIN/EN/ASME and specialist sources for marking and impact test values – the legal statements follow Directive 2014/68/EU and the German Betriebssicherheitsverordnung. No standard text was reproduced – the current original edition is binding. Comparisons with EN grades are orientation, not equivalence. Information without guarantee, no legal advice, no prices.