Abstract: At 6:30 p.m. on January 6, 2017, employees were tasked with pressure washing the interior of a vessel. As the workers were cleaning the interior of the vessel, one of the employees was hit with hot liquid which came from above at the top of the vessel. The employer utilized the host company's lock-out/tag-out procedures. Investigation revealed that there was an upset condition in one of the evaporator vessels upstream of the one being cleaned which forced hot sugar juice into the vapor piping of the system. The butterfly valve which was at the top of the vessel was only wired shut and not locked out. When the hot sugar juice expanded into the vapor piping it pushed the butterfly valve open causing the hot sugar juice past the valve an down onto the employees below inside the vessel. The employee was scalded by hot liquid and hospitalized. The employee had third degree burns over 75% of their body.