Welding, Cutting, and Hot Work Safety
Welding, cutting, and brazing operations create multiple simultaneous hazards: fire and explosion from sparks and molten metal, toxic fumes and gases, ultraviolet and infrared radiation (arc eye and skin burns), electrical shock from welding circuits, and explosion risk from compressed gas cylinders. OSHA addresses these hazards under 29 CFR 1910.252 through 1910.255 for general industry. A hot work permit system is the primary administrative control — it requires identification of combustibles within 35 feet of the hot work, designation of a fire watch, and supervisor sign-off before work begins.
Welding fumes present serious respiratory hazards depending on the base metal and coatings involved. Carbon steel welding generates iron oxide fumes; stainless steel generates hexavalent chromium (a known carcinogen); galvanized steel generates zinc oxide fumes (metal fume fever); and lead-painted surfaces generate lead fume. OSHA 1910.252(c) requires ventilation sufficient to keep fume concentrations below PELs — general mechanical ventilation, local exhaust ventilation (LEV) at the source, or respiratory protection when ventilation is insufficient. Supervisors must consult the SDS for base metals, coatings, and filler materials to identify toxic components.
A fire watch must be posted during all hot work operations and must remain on duty for at least 30 minutes after welding, cutting, or heating is completed. The fire watch must be equipped with a fire extinguisher appropriate for the fire class and must be trained in its use. Fire watches may not perform other duties while on watch — their sole responsibility is monitoring for fire. Combustible materials within 35 feet of the hot work must be moved, covered with fire-resistant blankets, or have hot work prohibited unless the area is made fire-safe.
Welding in confined spaces creates additional hazards: oxygen-deficient atmospheres from inert shielding gases (argon, helium, CO2), explosive accumulations of combustible gases from purging or leaks, and toxic fume concentration with no dilution ventilation. Before welding in a confined space, atmospheric testing must be conducted for oxygen level (19.5–23.5%), flammable gas/vapor (below 10% LEL), and toxic contaminants. Continuous ventilation is required. Gas cylinders must remain outside the confined space — only the torch and hoses are brought in. When welding is stopped, torches must be removed from the space.