What is the standard pipe bevel angle for welding?

The standard pipe bevel angle for butt welding is 37.5° from the pipe axis (52.5° included angle when both sides are bevelled). This is specified in BS EN ISO 9692-1 and AWS D1.1. A 37.5° bevel on 13 mm wall pipe requires a cut-back of approximately 10 mm.

How do you calculate pipe bevel angle?

Pipe bevel angle (θ) is calculated using: θ = tan⁻¹(cut-back ÷ wall thickness). For example, a 10 mm cut-back on 13 mm wall pipe gives tan⁻¹(10 ÷ 13) = 37.5°. To find the cut-back from a known angle: cut-back = tan(θ) × wall thickness.

What is the difference between bevel angle and included angle?

The bevel angle is measured on a single pipe end from the pipe axis. The included angle (or groove angle) is the total angle between both prepared faces when two pipes are butted together — it is twice the bevel angle for a symmetrical joint. A 37.5° bevel angle gives a 75° included angle.

What does cut-back mean on a pipe bevel?

Cut-back (also called bevel depth or face recess) is the horizontal distance the bevel face extends back from the pipe end. It is the distance measured along the top of the pipe wall from the outer edge to where the bevel begins. Cut-back determines the bevel angle for a given wall thickness.

Pipe Bevel Angle Calculator — Cut-Back & Weld Prep Geometry

37.5°

Standard pipe bevel (BS EN ISO 9692)

tan⁻¹

Inverse tangent formula

±0.1°

Calculator accuracy

2-way

Forward & reverse calc

Pipe Bevel Calculator

Cut-Back Distance (b)

Wall Thickness (a)

Quick Presets

Bevel Angle

37.5°

tan⁻¹(10 ÷ 13) = 37.5°

Included angle (both sides): 75.0°

Common Bevel Angles — Cut-Back by Wall Thickness

Cut-back values rounded to 1 decimal place. Verify against applicable welding procedure specification (WPS).

The Formula Explained

The bevel angle (θ) is the angle between the bevel face and the pipe axis. Because the pipe wall forms a right triangle with the cut-back as the horizontal leg (b) and the wall thickness as the vertical leg (a), the bevel angle is simply the arctangent of cut-back divided by wall thickness:

                    θ = tan⁻¹(b ÷ a)

                    cut-back = tan(θ) × a

The included angle of the weld groove is twice the bevel angle when both pipe ends are bevelled symmetrically. The standard 37.5° bevel gives a 75° included groove angle, which allows adequate welder access for root runs.

Checking a Bevel with a Protractor

Measure the wall thickness accurately with a vernier calliper
Use a digital bevel protractor or angle gauge on the prepared face
Alternatively, measure the cut-back distance and calculate using tan⁻¹
Check for consistent bevel around the full pipe circumference
Verify root face (land) dimension separately — typically 1–3 mm
Record against WPS tolerance: usually ±2.5° for most codes

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Pipe Bevel Angle Calculator

The Formula Explained

Checking a Bevel with a Protractor

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