Abstract: At approximately 11:20 a.m. on May 28, 2012 Employee #1, a 50-year-old male with Verso Paper Corporation was working in the vicinity of the mill air receiver tank when it exploded. Earlier in the day, a leaking water valve was discovered under the Number three Paper Machine and employees were instructed to shut down that machine and supporting equipment so the valve could be repaired. Specific lockout/tagout procedures were not utilized. One of the pieces of equipment that was shut down was the drill well pump, which caused a decreased flow of water to the air compressors. When an employee was told to turn the drill well pump back on, he discovered that someone else had already done it. There are five Gardner-Denver air compressors, with two air receiver tanks (one for Mill Air and one for Instrument Air) and two chiller/dryer units located on the floor above the air compressors. Two coworkers heard a loud air release while they were in the break room adjacent to the Air Compressor Room. The surviving coworker in the tank area, said he saw some smoke or light haze and saw fire shoot up and out of AC Number three approximately three-to-six feet in the air. He turned to run out of the area and had taken three-or-four steps before there was a loud explosion and he went flying. He did not see what happened to Employee #1. The Mill Air receiver tank exploded, causing damage to the building and contents of the building. In 2010, the system for cooling the oil for the air compressors was changed from air cooled to water cooled. Shutting the well water off decreased the water flow to the air compressors, which resulted in AC number-four and number-five shutting down due to high temperatures of 200 and 205 degrees Fahrenheit range. AC number three continued to run and overheated. Company records show that the cooling water flow had decreased (200 gpm to 59 gpm) during the hours prior to the explosion and the oil temperature in AC number three had increased to over 308 degrees prior to the explosion. The MSDS indicates the AEON 4000 Compressor Oil used in the five air compressors had a flash point of 210 degrees F. The explosion resulted in killing Employee #1 and four coworkers being sent to a local hospital where they were treated and released.