Supervision, Planning and Cost Awareness
This module tests the supervisor's role under ISO 14731 - planning work so that qualified procedures, qualified welders and controlled consumables converge at the right time - and the arithmetic of weld cost.
Supervision duties
- Confirm the correct WPS revision is at the workplace and being followed.
- Confirm each welder's ISO 9606-1 qualification covers process, position, thickness and material; validity is confirmed by the employer at intervals (typically every six months) with revalidation at two years.
- Control consumables: baking, holding, issue quantity, return and quarantine.
- Set hold points for NDT and dimensional checks before the next operation covers the weld.
Cost structure
Labour, consumables, power, equipment depreciation, preparation, NDT and rework. Weld metal cost scales with the square of the leg for fillets, so over-sizing is expensive.
Worked example: cost per metre
An 8 mm leg fillet, 1 m long: cross-section = 8²/2 = 32 mm²; volume = 32 000 mm³ = 32 cm³; mass = 32 × 7.85 ≈ 251 g. At a deposition rate of 2 kg/h arc time, arc time = 0.251/2 = 0.126 h ≈ 7.5 min. With an operating factor of 40%, total time = 7.5/0.4 ≈ 18.8 min. At €45/h, labour cost ≈ €14.1 per metre, before consumables, power and overheads. Operating factor must divide, not multiply.
Traps
- Multiplying by the operating factor instead of dividing.
- Ignoring rework and repair allowance, which can double the real cost on positional work.
- Forgetting that a 10 mm leg fillet has about 56% more area than 8 mm.
- Assuming a longer arc-time figure means lower cost when deposition rate is unchanged.