WASHINGTON — The National Transportation Safety Board says it is “looking closely” at aluminum protective covers on tank cars involved in the East Palestine, Ohio, derailment, over concerns those covers melted on three of the cars, which may have hampered the performance of pressure relief devices.
The issue occurred on three of the five cars carrying vinyl chloride in the Feb. 3 derailment. The covers house the pressure relief devices that vent gas to relieve tank pressure. In a press release today (Thursday, March 2), the NTSB says it is concerned aluminum from those covers may have melted and dripped into some of the pressure relief devices, possibly degrading their performance.
The devices relieve pressure that occurs when a tank car heats when it is exposed to fire, releasing a small quantity of the material inside — as shown in the illustration at right from East Palestine— then closing when normal pressure is restored. This reduces the potential for a catastrophic tank failure.
The cars involved, with aluminum protective covers, were built in the 1990s. The NTSB says it is now working to determine the size of the fleet of cars that might be affected. The pressure release devices and valves from the five cars are being sent to a testing facility for further examination.
The NTSB issued its preliminary report on the East Palestine derailment on Feb. 23 (see “Hot box warning came too late …,” Trains News Wire, Feb. 23, 2023), but its investigation is continuing. Additional information is available on the investigation web page.
Can understand why aluminum covers. Steel one are going to be much heavier. Suspect this revelation will call for an immediate FRA directive to replace the Aluminum covers based on how quickly steel can be built.
This revelation will cause a lawsuit against those car owners with Aluminum covers. Maybe even the car builders.
further thoughts. Everything around the whole safety valve needs to have no Aluminum parts on all Haz Mat cars as the cars can always placed next to a car that has a high burning temperature. All cars is going to make a FRA directive more widespread.
Which is odd as the melting point of aluminum is 1000 degrees higher than steel. So what happened to the aluminum cover that didn’t happen to the steel ones?
You have it reversed, sir: the melting point of aluminum is around 1220 degrees F, while steel melts around 2300-2800 degrees F depending on exact composition.
The US Navy has stopped using aluminum in the construction of warships. It was a legacy of the Falklands war were two of the British ships lost were attributed in part to the use of aluminum. In addition the USS Stark damage was worsened by aluminum in its construction.
This may be the answer to one of the lingering unanswered questions.