Abstract: On March 24, 2007, Employee #1 was descaling the tubes of a heat exchanger. The descaling operation was prosecuted from inside the upper domed bulk head (8-ft in diameter and 7-ft high) on top the forty foot exchanger tubes using a 7,000-psi spray washer equipped with a rotating nozzle attached to a 50-ft hose and foot controller. Access to work area was through a man port following confined space entry procedures and a designated observer on the cat walk 70 ft above ground level. Lighting and ventilation was provided. The greatest concentration of scale was found in the bottom ten feet of the tubes. The work procedure was to lower the nozzle into the tube until a tape wrapped on the hose indicated to start pressure flow. The hose is fed into the tube until a maximum depth tape maker is reached. The hose is withdrawn from the tube until a yellow marker is visible signaling to stop the pressure feed and extract the nozzle from the tube. A second red safety marker was placed on the hose giving notice to stop pressure because the nozzle is within three feet from leaving the tube. Employee #1 pulled the nozzle clear of the tube with the pressure on, resulting in the hose striking him due to whipping action. Employee #1 was wearing a face shield but he sustained injuries including loss of teeth, facial lacerations and facial bone fractures. Employee #1 was extracted by litter and retrieval equipment. Post event testing of the system did not reveal any defect in operation. Employee #1 was hospitalized.