Welding Processes and Equipment
Processes a Level 1 inspector must recognise
You will not operate every process, but you must recognise the equipment, consumables and typical defects of the common arc processes: SMAW (stick), GMAW (MIG/MAG), FCAW, GTAW (TIG), SAW, and the resistance and oxy-fuel processes encountered in some fabrication. For each, know the polarity options, the role of shielding gas or flux, and the defect signatures. SMAW with a cellulosic electrode on pipe root gives deep penetration but risks slag entrapment; GMAW short-circuit transfer is prone to lack of fusion; FCAW self-shielded is used outdoors where gas shielding would blow away; SAW gives high deposition but must run on flat or near-flat positions.
Variables that change the result
Current, voltage, travel speed, electrode angle, stick-out and gas flow all interact. Too little current gives lack of fusion and poor penetration; too much gives undercut, spatter and burn-through. Excessive travel speed narrows the bead and encourages undercut; too slow a speed piles up reinforcement and can cause slag traps. Gas flow that is too low admits porosity; too high causes turbulence and also porosity. A frequent exam trap is a question that blames the wrong variable, for example attributing porosity solely to damp electrodes when the gas flow was the real cause. Read the whole scenario before choosing.
Worked example and rule of thumb
A GMAW butt weld shows worm-like porosity along the centreline. Check gas supply and flow, nozzle condition, draft in the workshop, and wire condition before blaming the operator. Rule of thumb: for GMAW, set gas flow around 10 to 15 litres per minute in still air, and double-check whenever the work is outdoors or near a fan. Also remember equipment checks: cables, return clamps, regulators and electrode condition are inspection items before welding starts.