33 CFR § 401.69 - Hazardous cargo vessels.
For the purpose of these Regulations, a vessel shall be deemed to be a hazardous cargo vessel in the following cases:
(a) A tanker carrying fuel oil, gasoline, crude oil or other flammable liquids in bulk, having a flashpoint below 61 °C, including a tanker that is not gas free where its previous cargo had a flashpoint below 61 °C;
(b) A tanker carrying compressed liquefied gases, bulk acids or liquefied chamicals;
(1) In excess of 50 tonnes of gases, compressed, liquified or dissolved under pressure (IMO Class 2),
(2) In excess of 50 tonnes of flammable liquids having a flashpoint below 61 °C (IMO Class 3),
(3) In excess of 50 tonnes of flammable solids, spontaneously combustible material or substances emitting combustible gases when wet (IMO Class 4),
(4) In excess of 50 tonnes of oxidizing substances or organic peroxides (IMO Class 5),
(5) Any quantity of poisonous (toxic) substances and infectious substances (IMO Class 6),
(6) Any quantity of radioactive substances (IMO Class 7),
(7) In excess of 50 tonnes of corrosive substances (IMO Class 8),
(8) Any quantity of metal turnings, borings, cuttings, or shavings in bulk having a temperature on loading or in transit in excess of 65.5 °C, and
(9) Any quantity of grain that is under fumigation, where the chemical being used is hazardous to human life.
(10) Any quantity of direct reduced iron (DRI).