LINE OPENING INCIDENT

 On July 24, 2020, at 1:20 p.m., an accidental release of approximately 100 milliliters of silicon tetrachloride seriously injured two contract workers at a facility in Tennessee.

At the time of the event, contract workers were disassembling a 2-inch flange to remove a blind (a solid metal plate used for isolating equipment) before reinstalling a section of piping that had been taken out and cleaned. This type of equipment opening is commonly called 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 using chemical suits or rubber boots because the piping system had been taken apart the previous day for the cleaning activity. This additional protective equipment was required by the safe work permit, authorizing 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.
 

Based on the factual investigative information the CSB obtained from the company and OSHA, the CSB determined that the probable cause of the accidental silicon tetrachloride release was the failure to effectively isolate, flush, and drain the piping system before turning it over to the contract workers for disassembly. Not using PPE that could protect the workers from being splashed with corrosive silicon tetrachloride contributed to the severity of the incident.

Source: CSB.gov