Health, safety and environmental protection
This domain examines hazard identification, exposure control and legal duties around welding. The IWE is expected to design work so that hazards are eliminated or controlled at source, and to justify controls with exposure reasoning.
Fume, gases and ventilation
Welding fume contains manganese, nickel, chromium VI from stainless, and ozone from GTAW. Control is by local exhaust ventilation at the arc, with capture velocity typically 0.5–1 m/s at the extraction nozzle. Dilution ventilation is a secondary measure and must be sized from generation rate.
Worked example: dilution airflow
A process generates 15 mg/min of a fume constituent. The exposure limit is 0.1 mg/m³ and background is 0.01 mg/m³. Required airflow Q = G / (C − C₀) = 15 / (0.1 − 0.01) = 167 m³/min. That large flow shows why on-torch extraction is preferred to general dilution, and why the calculation must use the correct substance limit and background.
Other hazards
- Electric shock: no-load voltage limits, dry gloves, RCD protection, isolated returns.
- Fire and explosion: hot-work permit, fire watch, removal of combustibles, gas purging controls.
- Confined spaces: gas testing, rescue arrangements, forced ventilation.
- Radiation and noise: arc eye prevention, screening, hearing protection.
Environment
Waste segregation for electrodes, flux, swarf and packaging; fume extraction discharge; spill control for gases and chemicals. Permits and risk assessments must be specific to the task, not generic.
Traps
Using a single exposure limit for all fume constituents; relying on dilution ventilation where LEV is feasible; ignoring chromium VI in stainless welding; treating a hot-work permit as a substitute for fire watch.