Crossover Piping on Highway Tanks

Transport Canada (TC) has become aware that some multi-compartment highway tanks were manufactured with a crossover pipe (also called an equalization line) without an isolation valve.

They consider such highway tanks as having a single compartment because there is no isolation valve in the crossover piping that connects two compartments separated by a bulkhead. These highway tanks are non-compliant with CSA standards B620 and B621 since they have no means of isolating one compartment from another, making it impossible to pressure test each compartment individually.

While these types of highway tanks typically carry crude oil, carriers might use them to transport more than one type of dangerous good simultaneously without realizing the compartments are interconnected. TC has prepared an explanatory note for industry that provides information on the issue and indicates that immediate compliance with CSA Standards is expected.

TC’s Transportation of Dangerous Goods Inspectors will be inspecting facilities that manufacture, modify, test and/or inspect highway tanks.  TC asked a number of associations, including the CPA, to share the explanatory note with their membership in order to increase awareness, compliance and public safety.

For any technical questions about CSA B620 or B621, email TDG Engineers at: tdgcontainers-tmdcontenants@tc.gc.ca. Please include "Highway Tanks – Crossover piping" in the subject line.