WASHINGTON — The pressure release valves on some of the tank cars carrying vinyl chloride in the East Palestine, Ohio, derailment of a Norfolk Southern train may have been compromised, the National Transportation Safety Board said today.
The valves maintain internal pressure at safe levels by venting material to reduce the potential for a catastrophic tank car failure, the NTSB said following an initial round of tests on the pressure release devices on the five derailed tank cars.
Officials, fearing that one or more of the tank cars might explode, decided to do a controlled venting and burn of the vinyl chloride following the Feb. 3 derailment.
The NTSB said that testing of the pressure relief devices revealed that:
- Anomalies with the function of some pressure relief devices may have compromised their pressure relieving capability. Further testing and evaluation will be required.
- According to the manufacturer’s part specifications, one of the pressure relief device’s internal springs was coated with aluminum, which is not compatible with vinyl chloride.
- There was no evidence that melted aluminum entered the tank.
The NTSB had previously indicated concern that aluminum covers for the valves had melted and may have interfered with their ability to function [see “NTSB expresses concerns …,” Trains News Wire, March 2, 2023]
The NTSB continues to assess if the debris impacted the pressure relief device operation.
The toxic derailment has placed railroad safety under an intense spotlight. NS CEO Alan Shaw and NTSB Chair Jennifer Homendy are scheduled to appear before a Senate committee on Wednesday.
Share this article
