Health, safety and environmental protection
This domain tests recognition of welding-specific hazards and the hierarchy of controls, with the standards that quantify them.
Core rules
- Fume: emission rate is measured by the ISO 15011 series. Control by process substitution, then local exhaust ventilation at the arc, then RPE. Stainless fume carries hexavalent chromium and nickel; manganese is the concern with carbon steel.
- Gases: TIG generates ozone and NOx; shielding gases displace oxygen in confined spaces - purge and monitor before entry.
- Radiation: UV and IR; use EN ISO 11611 clothing, suitable eye protection and EN ISO 25980 screens.
- Electrical: open-circuit voltage, damaged torch leads, poor return-clamp contact; wet conditions raise the risk.
- Fire and cylinders: hot-work permit, fire watch, acetylene cylinders upright, no copper fittings, flashback arrestors.
Worked example
Welding stainless inside a tank. General dilution ventilation is not a control, because fume accumulates in the breathing zone. The answer is extraction at the arc, forced ventilation, oxygen and flammable-gas monitoring before and during entry, a rescue plan, and RPE with an A2P3 filter if fume remains above the exposure limit. The space is also permit-controlled entry, not simply a hot-work job.
Traps
Using oxygen to ventilate; assuming a welding helmet protects the lungs; ignoring fume from gouging and grinding; leaving cylinders unsecured; treating PPE as the first control rather than the last.