Standards · ASME and ASTM · ASME B16.25

ASME B16.25: Buttwelding ends

Preparation of the welding ends of pipe, fittings, flanges and valves that are joined by butt welding: bevel geometry, transitions of thick walls, internal end preparation, with and without backing rings or consumable inserts.

Issued by: ASME
Edition (publisher, as of 2 October 2026): 2022
Dimension standard: Buttwelding ends
European counterpart: EN ISO 9692-1 / EN 10253 / EN 1092-1
Belongs with: ASME B16.9 · ASME B16.5 · ASME B36.10M
At Zickwolff: we carry – from stock or to order, lead time on request

Scope: sizes, classes, grades

The usual bevel is 37.5° ± 2.5° with a root face of 1.6 ± 0.8 mm (single V) – thick walls get a compound bevel. Thin walls (below about 5 mm, austenitic below 3 mm) are cut square or lightly bevelled. The standard is referenced by B16.9, B16.5 and the ASTM pipe specifications for plain or bevelled ends.

Product form

A geometry standard – it names no materials.

The European counterpart – and the limits of the comparison

EN ISO 9692-1 (weld preparation) and the end preparations of EN 10253 and EN 1092-1 are the European counterparts.

European fittings and pipes are usually bevelled 30° +5°/−0° with a root face of 1.6 ± 0.8 mm up to 22 mm wall, ASME 37.5° – when an ASME fitting meets an EN pipe the bevels do not match and the weld seam must be prepared accordingly. Thick-wall transitions and bore matching are design decisions, not stock items.

“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

Not marked on the part – the bevel is visible. The fitting or pipe carries its own marking (B16.9, A106 ...).

The standard family: dimensions, material, pipe

ASME B16.9 · ASME B16.5 · ASME B36.10M

At Zickwolff

Our ASME fittings and weld-neck flanges come with bevelled ends to B16.25 – tell us the mating pipe and wall so that the bevel fits.

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 B16.25

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.

Why 37.5° and not 30°?

Two traditions: ASME B16.25 standardised 37.5° ± 2.5°, EN 10253 and EN ISO 9692-1 work with 30° +5°/−0°. Both weld well – but a joint between them needs a matched preparation and a welding procedure that covers it.

What does a thin-wall end look like?

Below about 5 mm wall (austenitic below 3 mm) the end is cut square or lightly bevelled – a full V bevel would leave no root face.

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

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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.

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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.