Practical welding competence
Practical welding competence tests whether you can set up and produce a sound test piece to ISO 9606 and explain every choice - position, polarity, current, technique and interpass care.
Qualification framework
ISO 9606-1 essential variables include process, product type (plate or pipe), joint type, filler, position, thickness and outside diameter ranges. Positions: PA flat, PB horizontal-vertical, PC horizontal, PD horizontal overhead, PE overhead, PF vertical-up, PG vertical-down, H-L045 pipe at 45°. A qualification covers a range, not only the test piece.
Technique
- Arc length: short for MMA to protect the pool; TIG arc length roughly equal to electrode diameter.
- Angles: work angle splits heat between plates; travel angle pushes (MAG) or drags (MMA), about 10–15° from perpendicular.
- Weave: commonly limited to about three electrode diameters in MMA to avoid slag traps and excess heat input.
- Root: keyhole control, gap and root face matter more than current; fill the crater.
Consumables and parameters
Basic electrodes run on DCEP; MIG gas 12–18 L/min; stick-out affects current in MIG/MAG; clean each pass.
Worked example
Vertical-up MMA root on 10 mm plate: 3.2 mm basic electrode, about 90–110 A, DCEP, short arc, slight upward weave. Low current keeps the pool from falling out, short arc gives penetration and gas protection, vertical-up gives better bead shape and toughness than vertical-down on thick steel, and DCEP suits basic coating.
Traps
Choosing high current to get penetration and burning through; long arc causing porosity; excessive weave; not cleaning slag between passes; ignoring the qualification range when switching thickness or position.