At the time of the event, contract workers were disassembling a 2-inch flange to remove a blind (a solid metal plate used to isolate equipment) before reinstalling a section of piping that had been removed and cleaned. This type of equipment opening is commonly referred to as a “line opening” or “performing a line break.”
The contract workers performing the line opening wore personal protective equipment (“PPE”), including full-face respirators, chemical gloves, and fall protection. The contractor’s pre-job safety analysis form did not require the use of chemical suits or rubber boots because the piping system had been dismantled the previous day for cleaning. This additional protective equipment was required under the facility’s Safe Work/Line Break permit, which authorized the contractor to perform the line-opening work. As the workers disconnected the flanged connection bolts, they were splashed with corrosive liquid silicon tetrachloride that had leaked past an isolation valve and pressurized the piping, seriously injuring the two contract workers with chemical burns.