Weld symbol
Double bevel groove weld symbol
One member bevelled from both faces while the other stays square, giving a K-shaped cross section. Two half-vee symbols sit on the reference line, one above and one below.
Reads as: Arrow side: bevel-groove weld, 3/8 size, 45° groove angle, 1/8 root opening. Other side: bevel-groove weld, 3/8 size, 45° groove angle.
How to read it
A double bevel is the single bevel done twice on the same member, once from each face. The other member is left square and passes through the middle. In cross section the preparation looks like a K lying on its side, which is why fabricators often call it a K preparation. On the drawing you see the half-vee symbol above the reference line and again below it.
The broken arrow still matters and still identifies the member that gets cut. Because both preparations are on the same member, the break resolves the same ambiguity as on a single bevel: which of the two members meeting at the joint is the one to prepare. On a tee joint that is normally the web or the attached member rather than the continuous flange.
Each face is dimensioned separately. The angle beyond each sloped face is that face's bevel angle, the depth to the left of each symbol is how far that preparation is cut and filled, and the root opening is written once for the joint. Asymmetric double bevels are common where one face is easier to reach or where the joint is welded in position.
The reason to prepare from both faces on a tee is the same as on a double-V butt: less weld metal than a single deep preparation, and balanced shrinkage across the joint so the upright does not pull toward the welded face. It also lets welding alternate side to side, which spreads heat input along a long member.
Where each dimension goes
- Bevel angle on each face
- Angle of that face's preparation relative to the plate surface. The two faces can carry different angles.
- Depth on each face
- How far that preparation is cut into the prepared member and filled with weld metal.
- Root opening
- Gap between the prepared member and the square member, written once for the joint.
- Broken arrow
- Identifies which of the two members is bevelled from both faces.
- Root face or land
- Unprepared thickness left between the two bevels, normally dimensioned on the joint detail.
Worked examples
Symmetric K preparation on a tee
“Bevel the web 45 degrees from both faces, 1/2 deep each, with a 1/8 root gap.”
Matching half-vee symbols above and below the line describe the same member prepared twice. Equal angles and depths make the preparation symmetric about the web's mid-thickness.
Double bevel with reinforcing fillets
“Fill both bevels 3/8 deep and cap each with a 5/16 fillet at the toe.”
The two groove symbols carry the preparation depth while a convex contour on each face signals the reinforcing cap that blends the weld into the through member.
Common mistakes
- Bevelling both members instead of preparing one member from both faces.
- Ignoring the broken arrow on a joint of unequal sections and cutting the wrong piece.
- Assuming the two bevel angles match when the symbol gives them separately.
- Filling one face completely before back gouging the other, which locks in angular distortion.
Typical joints
Related symbols
Practise reading welds, not just symbols
The drawing tells you what the weld should be. The gauge trainer is where you find out whether you can tell what it actually is.