49 CFR §172.512

1. (a)Capacity of 640 cubic feet or more. Each person who offers for transportation, and each person who loads and transports, a hazardous material in a freight container or aircraft unit load device having a capacity of 640 cubic feet or more shall affix to the freight container or aircraft unit load device the placards specified for the material in accordance with § 172.504. However:
   1. (1)The placarding exception provided in § 172.504(c) applies to motor vehicles transporting freight containers and aircraft unit load devices,
   2. (2)The placarding exception provided in § 172.504(c) applies to each freight container and aircraft unit load device being transported for delivery to a consignee immediately following an air or water shipment, and,
   3. (3)Placarding is not required on a freight container or aircraft unit load device if it is only transported by air and is identified as containing a hazardous material in the manner provided in part 7, chapter 2, section 2.8, of the ICAO Technical Instructions (IBR, see § 171.7 of this subchapter).
2. (b)Capacity less than 18 m 3 (640 cubic feet).
   1. (1)Each person who offers for transportation by air, and each person who loads and transports by air, a hazardous material in a freight container or aircraft unit load device having a capacity of less than 18 m 3 (640 cubic feet) shall affix one placard of the type specified by paragraph (a) of this section unless the freight container or aircraft unit load device:
      1. (i)Is labeled in accordance with subpart E of this part, including § 172.406(e);
      2. (ii)Contains radioactive materials requiring the Radioactive Yellow III label and is placarded with one Radioactive placard and is labeled in accordance with subpart E of this part, including § 172.406(e); or,
      3. (iii)Is identified as containing a hazardous material in the manner provided in part 7; chapter 2, section 2.8, of the ICAO Technical Instructions (IBR, see § 171.7 of this subchapter).
   2. (2)When hazardous materials are offered for transportation, not involving air transportation, in a freight container having a capacity of less than 640 cubic feet the freight container need not be placarded. However, if not placarded, it must be labeled in accordance with subpart E of this part.
3. (c)Notwithstanding paragraphs (a) and (b) of this section, packages containing hazardous materials offered for transportation by air in freight containers are subject to the inspection requirements of § 175.30 of this chapter.