On April 11, 2020, at 11:25 p.m., a spent caustic release occurred. One (1) operator was seriously injured by skin exposure to the corrosive liquid. At the time of the incident, the operator was implementing a temporary procedure to remove liquid from a chemical hose connected to fill a portable storage tank (“frac tank”) that the company was using to store spent caustic. Once the frac tank was full, air was used to clear the chemical hose before moving the hose to an empty frac tank.
When the operator opened the valve at the frac tank, pressurized fluid in the chemical hose flowed into the tank, erupting spent caustic from the unsecured top hatch (manway) and splashing the corrosive liquid onto the operator. The operator’s personal protective equipment (PPE) did not protect from caustic liquid exposure. It took the operator about two minutes to reach the closest plant safety shower to rinse off the corrosive liquid because there was no safety shower near the frac tank, despite the site requirement for a safety shower within 25 feet of the tank. The operator then went to the control room and reported the
incident. Emergency responders transported the operator to a hospital, where she was admitted for treatment of chemical burns.
The Facility estimated that approximately 20 gallons of spent caustic were released. The spent caustic was comprised of water, sodium hydroxide, sodium sulfide, sodium carbonate, and pyrolysis gasoline.
Based on the investigation, the CSB determined that the probable cause of the spent caustic release was pressurized fluid flowing from a chemical hose into a nearly full frac tank of spent caustic with an unsecured top hatch (manway). Contributing to the incident was the company’s use of these frac tanks to address a short-term reliability issue with the facility’s oxidizing reactor. Reliability problems with the oxidizing reactor resulted in the continual use of these frac tanks.
The facility’s written procedure to remove liquid from the chemical hose connected to the frac tank, which did not address securing the frac tank’s top hatch and provided a path for the spent caustic to be ejected from the tank, also contributed to the incident.
Not wearing appropriate PPE that could protect from caustic liquid exposure and the prolonged time it took for the operator to reach a safety shower and obtain medical treatment contributed to the severity of the worker’s injuries. Had safety showers been equipped with an alarm system and located closer to the area, the severity of the operator’s injuries could have been reduced.
Source: https://www.csb.gov/assets/1/6/csb_incident_reports_volume_one_2025-01-14_rev_1.pdf