Health, Safety and Environment
This module tests the specific hazards of arc welding and cutting and the engineered controls that come before personal protection.
Fume and radiation
- Welding fume is classified by IARC as Group 1 (carcinogenic to humans). Stainless steels add hexavalent chromium and nickel; manganese in steel consumables is linked to neurological effects.
- Control hierarchy: process substitution (e.g. low-fume consumables) → local exhaust ventilation or on-torch extraction → general ventilation → respiratory protective equipment as the last line.
- Arc radiation causes arc eye (photokeratoconjunctivitis), skin burns and long-term ocular damage; screens and suitable filter shades are mandatory, including for helpers.
Gases, cylinders and fire
- Acetylene is never used above about 1.5 bar gauge; flashback arrestors are fitted at both the regulator and the torch.
- Cylinders are stored upright, secured, away from ignition, with fuel and oxidant separated.
- Hot work requires a permit, removal of combustibles, and a fire watch continuing after work stops.
Worked example: confined space
A welder must repair a stainless tank interior. The correct sequence is: isolate and clean, issue a permit, then gas-test in the order oxygen first (19.5–23.5% vol), then flammables, then toxics. Provide forced ventilation, keep the gas cylinders outside with hoses entering the space, post an attendant, and add fume extraction plus RPE. Oxygen must never be used for ventilation or purging.
Traps
- Believing a filter respirator protects against oxygen deficiency - it does not; only supplied air or escape sets do.
- Using oxygen instead of compressed air to ventilate or purge.
- Testing for flammables before confirming oxygen level.
- Ignoring electric shock risk: reduced open-circuit voltage equipment, dry gloves and an RCD for wet or confined work.