Inspection Detail

Inspection: 316206259 - Ati Allvac

Inspection Information - Office: Sc Department Of Labor, Licensing, And Regulation

Investigation Summary

On June 26, 2012, Employee #1 was working as a heat treat operator at a metal alloy manufacturing facility. He and a coworker, who was also working as a heat treat operator, were monitoring the progress of steel rectangles that were cooling in a cryogenic nitrogen box. The cryogenic nitrogen box was used to supercool metal at a controlled rate. The thermocouple in the back right corner was giving readings outside the acceptable range of 0 to 30 degrees. Employee #1 went out to the nitrogen box to service the thermocouple that was reading approximately minus 40 degrees. The narrative did not state whether these measurements were in degrees Fahrenheit or degrees Celsius. The nitrogen box was constructed of steel and plywood. It had been designed by ATI Allvac in 1998. The nitrogen box was approximately 26 feet in length; 6 feet, 6 inches in width; and 4 feet, 10 inches in height, with the lid closed (7.92 meters long, 1.98 meters wide, and 1.47 meters high). When the lid was open, workers had to step up 17 inches (0.43 meters) into the box. The size of the opening that employees used to enter the box was approximately 26 feet (7.92 meters) in length and 6 feet, 1 inch (1.85 meters) in height. The internal width of the box was approximately 5 feet, 6 inches (1.68 meters). There were a total of seven risers inside the box. Each riser was approximately 10 inches (254 millimeters or 25.4 centimeters) in height. The metal walking surface inside the nitrogen box was icy and slippery, and the area was poorly lit. The nitrogen box's 3,800-pound (1,724-kilogram) lid was lifted by two Hydro-Line single-acting standard pneumatic cylinders on the right and left sides of the box. The cylinders had a 1.375-inch rod diameter, a 40 inch stroke, and a 6 inch bore. (3.5-centimeter rod diameter, 101.6-centimeter stroke, and 15.2-centimeter bore). The pressure of the air going through the flexible air hose was 98 psi (676 kilopascals or 6.76 bar) to105 psi (724 kilopascals to 7.24 bar). The flexible air hose, rated at 200 psi (1,379 kilopascals or 13.79 bar) was attached to a hard line using a brass coupling and an HS10 Dixon worm gear clamp rated for used up to 30 psi (207 kilopascals or 2.07 bar). The brass coupling connecting the hard line to the flexible air hose was rated at 150 psi (1,034 kilopascals or 10.34 bar). According to the manufacturer, the worm gear clamp was not adequate to hold the hose in place at a pressure of 98 psi (676 kilopascals or 6.76 bar). Employee #1 went inside the nitrogen box to reposition and secure the thermocouple. Employee #1 did not engage the safety arms while adjusting the thermocouples on the steel rectangles inside the box. As Employee #1 was inside the box, the hose clamp failed, and the lid closed. Employee #1 was asphyxiated due to nitrogen inhalation, according to the coroner. Secondary injuries were related to extreme cold, but they were not the cause of death. Two maintenance workers found Employee #1 30 minutes to 1 hour after the incident had occurred. There were four violations of OSHA standards related to the accident. Citations were also issued for not developing machine-specific lockout procedures and for not engaging the safety arms. An additional citation was issued for failing to install locking pins or other mechanisms to secure the lid of the nitrogen box in place. A final citation was issued for not training employees on the procedures for isolating the nitrogen box.

Keywords: MAINTENANCE, ASPHYXIATED, CONFINED SPACE, METAL SHOP, TOXIC ATMOSPHERE, INHALATION, EQUIPMENT FAILURE, LINE CONNECTOR, LOCKOUT, NITROGEN