Welding Safety Practice Questions

Explanation: ANSI Z49.1 requires a fire watch to remain for at least 30 minutes after hot work finishes to detect smoldering fires.

Explanation: Acetylene is dissolved in liquid acetone inside the cylinder. Laying it down allows liquid acetone to escape, damaging regulators and creating a fire hazard.

Explanation: Free acetylene becomes unstable and can explode violently if pressurized above 15 psig (103 kPa).

Explanation: Moisture (sweat/water) drastically reduces skin resistance, making even standard welding voltages potentially lethal.

Explanation: Ultraviolet (UV-B/C) radiation causes actinic keratoconjunctivitis (welder's flash), a painful inflammation of the cornea.

Explanation: Stainless steel contains high levels of chromium. Welding it generates fumes containing hexavalent chromium, requiring strict ventilation or respiratory protection.

Explanation: ANSI Z49.1 mandates that gas cylinders remain outside the confined space to prevent gas accumulation if a leak occurs.

Explanation: AWS F4.1 states containers must be thoroughly cleaned and often filled with water or inert gas to displace flammable vapors before hot work.

Explanation: OSHA requires a hearing conservation program at 85 dBA, though the PEL is 90 dBA. 85 dBA is the standard safety threshold for protection.

Explanation: Safety grounding limits the workpiece voltage to ground and helps prevent accidental shock if equipment is misconnected or insulation fails. The separate work lead returns welding current to the welding machine; AWS cautions that the work lead is not a grounding lead.

Explanation: Argon is heavier than air and can pool in pits, tanks, or low areas, displacing oxygen without warning.

Explanation: LEV (like fume extractor arms) removes contaminants at the source, preventing them from entering the welder's breathing zone or the general shop air.

Explanation: UV radiation decomposes chlorinated solvent vapors (degreasers) into Phosgene, a highly toxic gas even in small amounts.

Explanation: Hot work permits are management tools to ensure fire hazards are assessed and controlled before welding in non-designated areas.

Explanation: The cap protects the valve from snapping off if the cylinder falls, which could turn the cylinder into a missile.

Explanation: Synthetics like polyester melt into the skin when hit by sparks, causing severe burns. Natural fibers (wool, cotton) or leather are preferred.

Explanation: Primary voltage is the high input voltage from the shop mains. The welding machine transforms this to secondary (welding) voltage.

Explanation: Standard industry color code: Red for Fuel Gas (Acetylene), Green for Oxygen.

Explanation: Pure oxygen saturates clothing, making it extremely flammable. A tiny spark can cause the clothing to burst into intense flame.

Explanation: NEMA standards generally limit the OCV of manual welding machines to 80 Volts (AC/DC) to reduce shock hazard.

Explanation: High magnetic fields from resistance welding and high-frequency emissions from GTAW can interfere with pacemaker operation.

Explanation: Flashback arrestors stop the reverse flow of gas AND quench the flame front, preventing an explosion in the hose or regulator.