49 CFR §172.502

1. (a)Prohibited placarding. Except as provided in paragraph (b) of this section, no person may affix or display on a packaging, freight container, unit load device, motor vehicle or rail car—
   1. (1)Any placard described in this subpart unless—
      1. (i)The material being offered or transported is a hazardous material;
      2. (ii)The placard represents a hazard of the hazardous material being offered or transported; and
      3. (iii)Any placarding conforms to the requirements of this subpart.
   2. (2)Any sign, advertisement, slogan (such as “Drive Safely”), or device that, by its color, design, shape or content, could be confused with any placard prescribed in this subpart.
2. (b)Exceptions.
   1. (1)The restrictions in paragraph (a) of this section do not apply to a bulk packaging, freight container, unit load device, transport vehicle or rail car which is placarded in conformance with TDG Regulations, the IMDG Code or the UN Recommendations (IBR, see § 171.7 of this subchapter).
   2. (2)The restrictions of paragraph (a) of this section do not apply to the display of a BIOHAZARD marking, a “HOT” marking, a sour crude oil hazard marking, or an identification number on a white square-on-point configuration in accordance with § 172.323(c), § 172.325(c), § 172.327(a), or § 172.336(b) of this part, respectively.
3. (c)Permissive placarding. Placards may be displayed for a hazardous material, even when not required, if the placarding otherwise conforms to the requirements of this subpart.