Abstract: At 4:15 p.m. on September 27, 1990, Employee #1 went to the yard to get a Beal Trans-liner tanker trailer, #2988, (not hot) to bring into the shop. Using his sense of smell, rather than the Gas-Trac NGX5 tester provided by the employer, he determined that the tanker was not hot. When Employee #1 then proceeded to weld a tab on the crow's nest, an explosion occurred. He lost his balance and jumped to the ground, breaking his heel. Employee #1 was treated at the hospital and released. Apparently the trailer, which was supposed to be empty, and was not placarded, was hot and contained petrochemical residues. The manifest of the last cargo was not available.