NTSB scrutinizing performance of tank car covers in NS derailment

“When a tank car is exposed to fire conditions and its contents are heated, the pressure inside the tank rises. This can lead to loss of tank shell strength and eventually a breach,” NTSB said. “To protect emergency responders and the public from the possibility of catastrophic tank failure under fire conditions, the pressure inside tank cars must be controlled. PRDs are intended to regulate internal pressure by releasing small quantities of material and reclosing after normal conditions are restored. This reduces the probability of a breach in the tank shell and limits the amount of energy a breach can release if one occurs. Properly functioning PRDs thus reduce the potential for catastrophic tank failure.”

NTSB is focusing on aluminum protective housing covers used on three of the vinyl chloride tank cars. The aluminum protective housing covers were manufactured in the 1990s. 

The agency will be looking for industry data to determine how many of these tank cars are in service. 

The tank cars were DOT-105J300W tank cars.

Further testing will be conducted on the PRDs and the valve assemblies from the five vinyl chloride tank cars.

NTSB reiterated that it could issue urgent recommendations at any point during the investigation if warranted.

EPA orders Norfolk Southern to test for dioxins in East Palestine

Meanwhile, the Environmental Protection Agency has ordered NS (NYSE: NSC) to test the area near the derailment for dioxins.

The tests are in response to concerns voiced by East Palestine residents.

EPA will order an immediate cleanup of the area if the level of dioxins is unacceptable for human health and the environment, the agency said Thursday. EPA is also requiring NS to conduct a background study to compare dioxin levels around East Palestine with levels in areas not impacted by the derailment. This is because dioxins can also be found in urban and rural environments as a result of common activities such as burning wood and coal, EPA said. 

The agency said it would continue its sampling for “indicator chemicals” as well. Test results to date suggest a low probability of the release of dioxin from the derailment.

The agency is reviewing a draft plan developed by NS that would develop a dioxin “fingerprint” for soil sampling, so that scientists and EPA will be able to determine whether any dioxin from the derailment or the controlled release impacted the local environment, EPA said.

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Related links:

• Federal agencies, senators unveil plans aimed at boosting rail safety

• Ohio train derailment spurs rail safety advisory on hot box detectors

• EPA tells NS where to dispose of derailment’s contaminated waste

• Trade groups, unions differ in responses to NTSB report on NS derailment

• NTSB chair says NS train derailment was ‘100% preventable’

• NTSB issues initial findings on Norfolk Southern train derailment