ASME B16.25 standardises the preparation of buttwelding ends on piping components: the bevel angle, root face (land) and, where needed, inside contouring that let a welder make a sound full-penetration weld between a pipe and a fitting, flange or valve. Every buttweld fitting and weld neck flange we make is bevelled to ASME B16.25 unless the order specifies another end preparation.
This page summarises the main bevel details; the full requirements, including tolerances, are in the standard itself.
| Wall thickness | End preparation |
|---|---|
| Up to about 3 mm (light wall) | Square cut, or slight chamfer, as the welding procedure requires |
| Over 3 mm up to 22 mm (0.88") | Single V bevel, 37.5° ± 2.5°, with a root face of 1.6 ± 0.8 mm |
| Over 22 mm | Compound bevel: 37.5° to a depth of 19 mm, then 10° ± 1°, with a 1.6 mm root face |
When the inside diameters of the two parts to be welded do not match, for example a heavy-wall fitting on a lighter pipe, B16.25 describes how the inside of the thicker part is machined or tapered so that the root of the weld lines up. Pipeline fittings to MSS SP-75 use similar tapered transitions where the fitting wall is thicker than the pipe.
Weld neck and long weld neck flanges are also bevelled to ASME B16.25.
Every bevelled component is made from PMI-verified material, dimensionally inspected against the ordered standard and marked with material, size, rating and heat number. Orders are supplied with EN 10204 3.1 certificates; EN 10204 3.2 certification and inspection by the buyer's nominated third-party agency are available on request.
37.5° ± 2.5° with a root face of 1.6 ± 0.8 mm for walls over about 3 mm up to 22 mm. Thicker walls use a compound bevel with a 10° outer section.
A single 37.5° bevel on a thick wall would need a very large weld volume. The compound bevel reduces the amount of weld metal and welding time.
Yes, J-bevels and other special end preparations can be machined to your drawing instead of the standard B16.25 bevel.
Yes. Weld neck and long weld neck flanges are bevelled to ASME B16.25 for the bore and wall thickness ordered.