How to weld angle iron correctly?

Welding angle iron (L-angle) requires a specific technique to avoid distortion and ensure structural strength.

Preparation:

• Cleaning: remove mill scale, rust and paint from the whole area the weld and arc will reach, on both sides of the joint
• Edge preparation: on thick angle iron, a bevel prepared as the WPS specifies is needed for a full-penetration weld

Welding technique:

• Tack weld: tacks at both ends and in the centre; on a long angle, add regular intermediate tacks so the piece does not close up while welding
• Alternating welding: Weld one side then the other to distribute heat and avoid deformation. Or use skip welding sequence
• Electrode angle: keep the electrode on the bisector of the two faces of the angle iron, with a slight drag angle suited to the position

Distortion:

• Angle iron tends to close or open under heat
• Pre-clamp the angle iron in a jig or against a backup to maintain the 90° angle
• For large production runs, a slight pre-set in the opposite direction compensates for shrinkage