Federal agency cautions of chlorine railcar risks

A new federal safety bulletin warns of hazards from railcars containing chlorine gas and urges the Department of Transportation to strengthen regulations at unloading facilities.

The action by the US Chemical Safety Board came as the Department of Homeland Security announced plans to begin enforcing the first-ever chemical security regulations adopted in April.

The CSB bulletin specifically cautioned that "some chlorine railcar transfer systems lack effective detection and emergency shutdown devices, leaving the public vulnerable to potential large-scale toxic releases."

Chlorine railcars, it notes, "are equipped with an internal excess flow valve (EFV) that is designed to stop the flow of chlorine if an external valve breaks off while the railcar is in transit. However, these EFVs are not designed to stop leaks during railcar unloading, and the failure of a transfer hose may not activate the EFV and the toxic chlorine will continue to escape."

The bulletin urges facilities that unload such railcars to "install emergency shutdown systems that can quickly stop the flow of chlorine if a hose ruptures during the unloading operation."

Noting that about a third of water and wastewater systems that handle such railcars "continue to rely solely on the EFV," CSB members called on DOT to "expand its regulatory coverage to require facilities that unload chlorine railcars to install remotely operated emergency isolation devices to quickly shut down the flow of chlorine in the event of a hose rupture or other failure in the unloading equipment."