A change in receiving storage tanks kills one

A road tanker loaded with ammonia hydroxide was being unloaded into a polyethylene storage tank at the site of a chemical distributor.  This change was not taken through a MOC. The unloading was being accomplished by filling the vacant space above the liquid inside the tanker with compressed air, a standard method of unloading such tankers. When the tanker was emptied, the compressed air surged into the polyethylene storage tank, which was not designed to withstand that kind of pressure. The polyethylene tank ruptured, releasing a substantial volume of ammonia into the air. An employee, who was close to the drain valve on the tanker, inhaled a substantial volume of ammonia, He suffered serious chemical burns to his lungs, resulting in his death. 

Source:osha.gov