Fabrication, applications engineering and quality management
This domain connects design to shop-floor execution: fit-up, sequencing, distortion control, procedure adherence and productivity. The exam asks for practical decisions supported by numbers, from arc time to operating factor.
Fit-up, sequence and distortion
Root gap, mismatch and alignment must be within drawing and standard tolerances before welding. Distortion control uses balanced or back-step sequence, pre-setting, jigs, minimum necessary heat input and, where permitted, thermal or mechanical correction. Each correction route needs procedure approval, especially in pressure and structural work.
Worked example: arc time and operating factor
A butt weld is 1.2 m long with a deposited cross-section of 40 mm². Deposition rate is 2.5 kg/h and steel density 7.85 g/cm³. Deposited volume = 40 × 1,200 = 48,000 mm³ = 48 cm³; mass = 48 × 7.85 = 377 g. Arc time = 0.377 / 2.5 = 0.151 h ≈ 9.0 min. With a 40% operating factor, total attendance time = 9.0 / 0.40 = 22.5 min. The operating factor captures repositioning, cleaning, chipping and breaks; omitting it underestimates fabrication cost.
Application engineering
Procedures must be qualified to ISO 15614-1 and applied by qualified welders to ISO 9606-1. Consumable handling, storage and re-drying of basic electrodes protect against hydrogen. Rework and non-conformity need disposition authority, not ad hoc grinding.
Traps
Confusing deposition rate with melt-off rate; forgetting operating factor; ignoring back-gouging and root treatment in cost and time; accepting fit-up outside tolerance because "the weld will fill it".