WASHINGTON, D.C. (WKBN) – Testing by the National Transportation Safety Board (NTSB) revealed some anomalies in the pressure relief devices removed from the five rail tank cars that were hauling vinyl chloride.

The testing was done as part of an NTSB investigation of the train derailment of a Norfolk Southern train in East Palestine.

According to the NTSB, the pressure relief devices, or PRDs, regulate the internal pressure of rail tank cars by releasing material when under pressure, reducing the potential for a catastrophic tank failure. NTSB investigators recovered the PRDs and tested them at a facility in Texas.

The examination and testing revealed the following findings: 

  • NTSB testing found anomalies in the function of some PRDs that may have compromised their pressure-relieving capability. This will require further testing and evaluation to assess the impact on the operation of the PRDs.
  • ​According to the manufacturer’s part specifications, one of the installed PRD’s internal springs was coated with aluminum, which is not compatible with vinyl chloride. 
  • While aluminum debris from melted protective housing covers entered the PRD discharge areas, there was no evidence that melted aluminum entered the tank. The NTSB continues to assess if the debris impacted the PRD operation.

​The NTSB is continuing to conduct a safety investigation to determine the probable cause of the train derailment. Last month, the NTSB reported it was looking into an overheated wheel bearing. Additional actions may be recommended to prevent future train derailments as the investigation proceeds.

Additional information is available on the NTSB’s investigation webpage.