Welding Safety, Health, and Environmental Practices
Core Concepts
Candidates must know the fire triangle and hot-work permit system, the classes of fire and extinguisher selection (A, B, C, D, K), and the safe storage and handling of compressed gas cylinders (upright, capped, secured, separated by fuel type, oxygen and fuel gas at least 20 ft apart or by a 5-ft noncombustible barrier). Ventilation requirements, fume composition by process (manganese, hexavalent chromium from stainless, zinc from galvanized), and personal protective equipment selection - shade lens numbers per amperage, leathers, respirators - are heavily tested. Electrical safety includes secondary open-circuit voltage limits, grounding, and the danger of wet conditions. Also study noise, radiation (UV/IR arc flash), confined-space entry, and environmental rules for waste, fume, and cylinder disposal.
Traps
Questions love the near-miss distractors: an oxygen cylinder stored lying down, using water on a Class D metal fire, or assuming a dust mask equals a respirator. Watch for the difference between a hot-work permit and a general work permit, and remember acetylene must never be used above 15 psi gauge in a manifold or free in a pipe. Lens shade selection is by amperage, not by electrode type alone.
Worked Example / Rule of Thumb
Shade rule of thumb: for SMAW at 100 A use shade 10; at 200 A use shade 12; for low-amperage GTAW use shade 8–10. For cylinder separation, use the "20 ft or 5 ft barrier" rule: keep oxygen and fuel gas at least 20 ft apart or separate with a 5-ft-high wall rated at least 30 minutes.