1910.252(a)(3)(i) Used containers.
No welding, cutting, or other hot work shall be performed on used drums, barrels, tanks or other containers until they have been cleaned so thoroughly as to make absolutely certain that there are no flammable materials present or any substances such as greases, tars, acids, or other materials which when subjected to heat, might produce flammable or toxic vapors. Any pipelines or connections to the drum or vessel shall be disconnected or blanked.
This was a fatal accident in Brazil. Workers were making repairs to this Tanker Truck by welding on it. It had residual vapor, and the HW ignited the vapors, killing one worker and seriously injuring another.
