Some of the valves on railroad tank cars designed to keep volatile, toxic chemicals from exploding were damaged in the Ohio derailment last month as the train burned, investigators said Thursday.
Melted aluminum from protective covers on the valves raised the risk that the devices could malfunction, the National Transportation Safety Board said in an update to its probe of the Feb. 3 wreck in East Palestine.
No one was reported injured, but the massive derailment has reverberated through national politics and raised new concerns about the safety of toxic materials being shipped on U.S. railroads.
The 150-car train had 20 cars containing chemicals, including vinyl chloride — considered a carcinogen — as well as ethylhexyl acrylate and isobutylene, according to the Environmental Protection Agency. Eleven of those hazardous materials cars derailed, the NTSB has said.
Three days after the accident, authorities intentionally vented and burned five tank cars containing vinyl chloride, in a safety measure designed to relieve pressure and prevent an explosion that could eject chemicals and metal shrapnel.
The damaged vents identified by the NTSB were on three of the cars with vinyl chloride, the agency said. In the days after the accident, the temperature of the cars was increasing due to a chemical reaction.
Investigators stopped short of saying that the damaged valves led to the burning.
The Pipeline and Hazardous Materials Safety Administration issued a notice later on Thursday alerting railroads that the aluminum covers can melt and urging their replacement with steel ones.
PHMSA, an arm of the Transportation Department, said it’s concerned the melting covers may have heightened the risks after the initial derailment and fire.
Separately, the seven large railroads that operate in the U.S. have agreed to join a voluntary reporting system for workers to confidentially flag safety issues after Transportation Secretary Pete Buttigieg requested it last month.
In a letter announcing the acceptance, Ian Jefferies, the president of the Association of American Railroads, offered to work with authorities to improve the reporting system. It was started in 2007, but some railroads have since dropped out.
