Abstract: At 7:50 a.m. on March 1, 2017, Employee #1 and Coworkers #1 and #2, maintenance employees employed by a heavy equipment manufacturer, were engaged in equipment maintenance. Employee #1 was helping his coworkers repair the pump for the quenching unit located in front of the heat treat oven. They were using five-gallon pails to store the quenching liquid while they tried to bleed out the air in the cooling lines. There was no funnel that would enable Employee #1 to pour the oil into the machine correctly. Instead, he dumped the five gallons of oil from the pail through the front door where the quenching oil was used. Some of the oil ran down through a channel, came into contact with the heat treat oven door, and began to smoke. Employee #1 closed the outside door and waited a couple minutes. He then started to raise the door to check if the smoke was gone. Air entered the heat treat oven, and an explosion occurred. The door was blasted open, and fire flashed out. Emergency services were called, and Employee #1 was transported to the hospital. He was admitted and treated for first degree burns to the face.