Washington — The Pipeline and Hazardous Materials Safety Administration is alerting hazmat rail tank car owners and others of “the potential for certain manway assemblies with aluminum protective housing covers to melt when exposed to extreme heat.”
During the initial parts of its investigation into a Feb. 3 train derailment in East Palestine, OH, the National Transportation Safety Board found that three tank cars carrying vinyl chloride had aluminum covers.
“The primary function of a manway protective housing and cover is to protect tank car fittings, such as pressure relief valves and other fittings, from damage,” PHMSA says. “The investigation has yet to determine what impact, if any, the destruction of the manway protective housing covers and presence of melted aluminum inside the protective housing had on the performance of the pressure relief devices of the DOT-105 specification tank cars containing vinyl chloride or whether the loss of the covers allowed for excessive flame impingement damage to the fittings.”
PHMSA warns that, if the covers melt, they can present a hazard in pool fire situations. The agency recommends replacing the aluminum housings with carbon steel, which PHMSA says is a current industry practice.
“PHMSA and the Federal Railway Administration may take additional action in the future if investigations reveal that the destruction of the aluminum manway covers and presence of melted aluminum inside the protective housing significantly contributed to improper functioning of the pressure relief devices,” the safety advisory states.
