What steps should be taken to tanks, pipes, and vessels before a welder begins work to avoid gas- or fume-related explosions?

• A. Verify empty, thoroughly clean, inspect, and test for flammable residue
• B. Fill with inert gas and seal
• C. Rinse with water and dry
• D. Ignore if the vessel seems clean

Answer: (A)

Preventing gas- or fume-related explosions during welding starts with making sure that tanks, pipes, and vessels are free of flammable vapors before work begins. This means confirming they are truly empty of contents, thoroughly cleaning to remove oils, solvents, and other residues, inspecting for hidden deposits, coatings, or damage that could emit flammable vapors, and testing for any remaining flammable residue with the appropriate detector. If flammable vapors are detected, do not weld until the space has been purged and verified safe by the proper procedures. Simply inerting, rinsing with water, or assuming cleanliness is not reliable, and ignoring the risk even if the vessel seems clean can allow vapors to linger in pockets or porous surfaces. The emphasis is on removing all sources of ignition risk by emptiness, cleanliness, thorough inspection, and verification.