Bulk packages, cargo tanks, and portable tanks
What counts as bulk
A bulk package holds more than 119 gallons (450 L) of liquid or gas, or more than 882 lb of solid, and is loaded directly rather than in small packages. The tank endorsement is required when the vehicle carries tanks each over 119 gallons with an aggregate capacity of 1,000 gallons or more.
Knowing your tank
The specification plate tells you what you are hauling:
- DOT 406 - flammable liquids, non-pressure.
- DOT 407 - low-pressure chemicals.
- DOT 412 - corrosives.
- MC 331 - high-pressure gases such as LPG and anhydrous ammonia.
- MC 338 - cryogenic liquids. The plate also shows maximum allowable working pressure, capacity, and inspection and test dates. Cargo tanks are visually inspected and pressure tested on fixed schedules; an expired test date makes the vehicle illegal to fill.
Weight and outage
Never fill a liquid tank to the top. Product expands as it warms, so the rules require an outage - a vapor space. Check the marked maximum product weight against product density: a tank marked 45,000 lb carrying a product weighing 7.5 lb per gallon is limited to 6,000 gallons by weight alone, and must be filled below that to leave outage.
Driving a cargo tank
Liquid surge pushes the vehicle. Brake and corner smoothly, slow early, and expect a higher center of gravity and longer stopping distance.
Worked example
Your spec plate shows a required pressure test date two months in the past. You must refuse the load and notify the carrier - the shipper cannot legally fill a tank with an expired test.
Traps that cost marks
Treating a portable tank as a non-bulk package; using volume capacity as the only limit and ignoring density; assuming an annual external inspection satisfies the pressure-test interval.