The United States Pipeline and Hazardous Materials Safety Administration (“PHMSA”) clarified in an April 28th letter the Hazardous Materials Regulations (“HMR”) applicable to the marking of Department of Transportation (“DOT”) specification packagings.

The PHMSA letter was in response to a November 3, 2016 request by 220 Laboratories.

220 Laboratories asked whether it is:

. . .permissible for the specification marking and “M number” to be covered by an opaque label that can be removed easily during a DOT investigation.

PHMSA answered in the negative. The agency stated that in accordance with § 178.3(a)(1), the markings on a packaging must be in an unobstructed area, with letters and numerals identifying the standards or specification of the packaging. It also noted that § 178.3(a)(3) states “the markings must be stamped, embossed, burned, printed or otherwise marked on the packaging to provide adequate accessibility, permanency, contrast, and legibility so as to be readily apparent and understood.”

Therefore, the agency opined that covering the specification marking and “M number” with an opaque label would not meet such requirements.

A copy of the April 28th letter can be downloaded here.