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The United States Pipeline and Hazardous Materials Safety Administration (“PHMSA”) addressed in a December 6th letter the Hazardous Materials Regulation (“HMR”) applicable to the marking requirements for a Department of Transportation Specification MC 331 cargo tank.

The interpretive letter was a response to a query by Nutrien of Loveland, Colorado.

Nutrien provided PHMSA, pursuant to an October 10th email, a photograph illustrating the placement of inlet and outlet markings on an MC 331 cargo tank. It asked whether it complied with § 178.337-9(c) of the HMR.

PHMSA responded in the affirmative.

PHMSA notes that § 178.337-9(c) requires each cargo tank inlet and outlet, with the exception of gauging devices, thermometer wells, and pressure relief devices, be marked “liquid” or “vapor” to designate whether it communicates with liquid or vapor when the cargo tank is filled to the maximum permitted filling density.

The interpretive letter further concludes that:

. . . Provided the marking is readily visible, legible, durable to withstand transport conditions, and clearly associated with the corresponding inlet/outlet, the marking would satisfy the requirements of the HMR. The marking(s) requirement may be satisfied using various locations and methods, including marking on the cargo tank shell.

A copy of the PHMSA letter and the Nutrien email can be downloaded here.