THE LAST "TO" IN "LOTOTO" IS VERY IMPORTANT!

 On September 22, 2022, at approximately 9:00 a.m., a liquid mixture comprised of aniline, formalin, and hydrochloric acid was accidentally released, seriously injuring one contractor at a chemical manufacturing facility in Louisiana 

On September 20, 2022, two days before the incident, an off-site power outage caused an immediate loss of process flow in the methyl diamine unit. The lack of flow allowed solids to form throughout a piping system. Company personnel were clearing the solids from this piping on September 22 when the incident occurred.
At approximately 9:00 a.m. on September 22, two contract workers began opening a flange connection in the piping system. After the flanged connection was fully opened, an amount (approximately 28 ounces) of toxic and corrosive liquid containing aniline, formalin, and hydrochloric acid sprayed from the open-ended piping. Some of the released liquid contacted the face and neck of a third contract worker (“hot zone attendant”). The hot zone attendant was present to monitor the safety of workers inside the “hot zone”—a 30-foot diameter area marked by red barricade tape—and to help decontaminate any workers leaving the hot zone. While the workers inside the barricade were wearing personal protective equipment (“PPE”) that included chemical suits with hoods and full-face supplied air respirator masks, the hot zone attendant wore a chemical suit and hood but was not wearing face protection.

After being sprayed with the toxic and corrosive liquid, the hot zone attendant first showered in the unit and then again at the site’s medical facility. The hot zone attendant was then transported to a hospital, admitted for inpatient care, and successfully treated for exposure to aniline.
The company's investigation found that the hot zone attendant did not wear face protection because the operations team did not recognize the potential for pressurized liquid aniline to remain in the piping system. Energy isolation work (often referred to as line breaks) performed after the power outage involved opening multiple other piping connections, including a valve at the high point in the piping system. The operations team believed that this work had removed pressure from the system. A post-incident review of the process data, however, showed that pressure remained in some areas of the piping system. The company’s energy isolation plan did not include a review of the available local or computer control system data to ensure that the piping was not under pressure.

Probable Cause
Based on company's investigation, the CSB determined that the probable cause of the accidental release was the opening of the flange connection while portions of the piping contained pressurized liquid. The company's energy isolation plan contributed to the incident by not ensuring the piping was depressured before workers began disassembling the flange connection. Allowing a worker near this equipment opening activity who was not wearing protective equipment that could shield the worker’s face from being sprayed with the toxic and corrosive process liquid contributed to the severity of the incident. Had the worker been wearing protective equipment with a face shield, this incident likely could have been prevented. Additionally, reviewing available local or computer control system data prior to the work to ensure that the piping was not under pressure could have helped prevent this incident.

Source:CSB.gov