Abstract: At 3:00 p.m. on March 29, 1989, Employee #4 was signaling the crane operator of a 75 ton P & H hydraulic truck crane from the doorway of the third floor of the anhydrous car barn. Employees #1, 2 and 3 had walked out from the mezzanine level to get some fresh air. Old polyvinyl chloride pipe and scrap steel, 28 inches by 13 inches by 2 inches, on the roof of the anhydrous car barn fell approximately 25 to 30 feet, striking and rupturing a 4 inch cast iron line containing a 93 percent solution of sulfuric acid, releasing it. Employee #4 walked into the solution. All employees received chemical burns. Employee #1 and #2 have not returned to work.