Health, safety and environment
This domain tests hazard identification and control in welding workplaces: fume, radiation, electricity, fire and confined spaces. Expect questions on extraction, personal protective equipment, welding screens, hot work permits and atmospheric testing.
Fume, radiation and ventilation
Fume composition depends on process and consumable. Manual metal arc and flux-cored welding generate high fume levels; stainless consumables produce chromium, including hexavalent chromium, and nickel; manganese exposure is a concern in some consumables. Local exhaust ventilation at the arc is the primary control, with respiratory protective equipment as a supplement, not a replacement. Arc radiation causes photokeratoconjunctivitis (arc eye) and skin burns; EN ISO 25980 welding curtains protect bystanders. Ozone is produced by GTAW and plasma, particularly on aluminium.
Electrical and fire safety
No-load voltage is limited by EN 60974-1, typically to 48 V r.m.s. AC or 113 V peak. Work return clamps must be close to the joint, cables inspected, and gloves and screens dry and intact. Hot work permits, removal of combustibles, fire extinguishers and a fire watch after welding are standard controls.
Confined spaces
Test the atmosphere before entry and monitor continuously. Oxygen should be between 19.5% and 23.5%, flammable gas below 10% of the lower explosive limit, and toxic gases below their exposure limits. Ventilation, an attendant and a rescue plan are required.
Worked example
A tank reads oxygen 18.5%, flammable gas 0% and hydrogen sulphide 1 ppm. Entry must be refused. Reasoning: 18.5% oxygen is below the 19.5% threshold, so the space is oxygen-deficient; supplied-air or self-contained breathing apparatus plus ventilation and retesting are needed. Air-purifying respirators cannot correct oxygen deficiency.
Traps that cost marks
- Treating respiratory protection as a substitute for extraction.
- Entering a confined space after a single test without continuous monitoring.
- Omitting the post-weld fire watch.
- Assuming welding screens also control fume.