NTSB: Protective covers of hazmat tank cars melted
Tank cars carrying vinyl chloride in a train that derailed in East Palestine, Ohio, had aluminum protective coverings that melted into pressure valves, potentially “degrading” their performance, the National Transportation Safety Board said Thursday, prompting a federal safety advisory urging railroads to examine their hazmat tank cars.
The melting aluminum soaked into pressure relief devices that are critical to regulate internal pressure of a tank car during fire and overheating conditions, the NTSB said. The NTSB did not make final conclusions about whether the protective covering failure contributed to the chemical spill.
Properly functioning valves reduce the potential for catastrophic tank failure, the safety board said.
The Department of Transportation’s Pipeline and Hazardous Materials Safety Administration issued a safety advisory Thursday calling on railroads and tank car owners to track down tanks built with aluminum protective coverings. It urged them to replace them with steel coverings, which are the industry standard and can better withstand exposure to heat and fire.
Three days after the Feb. 3 derailment near the OhioPennsylvania border, officials decided to release vinyl chloride from five rail cars to prevent them from exploding, a controversial decision that sent more chemicals into the air and brought photos of a black plume looming over East Palestine.
Twenty cars in the 149-car Norfolk Southern train were carrying hazardous materials, 11 of which derailed, along with 27 cars containing nonhazardous cargo. Five derailed tank cars contained the vinyl chloride.
The NSTB said three of those tank cars were built in the 1990s with the aluminum protective covers, which investigators said are critical to protecting the tank pressure relief valves from damage.
While the advisory is a recommendation and not an order, it comes amid other efforts by the Biden administration to tackle rail safety after the derailment. On Tuesday, the Federal Railroad Administration issued an advisory urging railroads to improve their use of trackside safety detectors, which didn’t provide enough warning about a dangerously hot bearing before the Ohio derailment.
On Wednesday, the head of the Federal Railroad Administration returned to East Palestine to announce a series of inspections on rail routes carrying hazardous materials. Federal inspectors will assess the condition of rail infrastructure and compliance with safety rules. The agency also plans to inspect older tank cars.
Transportation Secretary Pete Buttigieg has issued several safety measures, and has called on the industry to offer paid sick leave and for Congress to raise fines for railroad safety violations. In the aftermath of the derailment, the agency said it would study the possibility of issuing rules to require railroads to adopt new braking technology on some trains.
The PHMSA, which sets regulation for the transportation of hazardous materials, said it wants railroads and tank owners to be aware of the melting potential for aluminum coverings. It recommended railroads consider replacing them with carbon steel coverings, which in other incidents have better survived fire. It said that is “likely due to carbon steel having a higher melting point than aluminum.”
“Although it is currently unclear what impact the protective housing covers may have had on the severity of the damages resulting from the derailment, PHMSA is concerned that the melting of these covers may present a danger in pool fire situations,” said the advisory signed by associate administrator William S. Schoonover.
Norfolk Southern did not immediately respond for request for comment. The Association of American Railroads referred questions about the tank cars to the Railway Supply Institute, which represents the car manufacturers. It said more than 99% of tank cars are owned or leased by shippers. Railroads own less than 450 tank cars out of the more than 400,000 active tank cars, according to the AAR.
The NTSB said investigators will further examine the pressure relief devices and valve assemblies from the five vinyl chloride tanks to determine any other conditions that might have affected their operation after the derailment.