Bulk Packages, Cargo Tanks, and Tank Vehicles
Bulk Packages, Cargo Tanks, and Tank Vehicles
This domain tests bulk packaging rules and the special handling of cargo tanks. Expect questions on the bulk definition, cargo tank specification plates, outage and filling limits, baffles, and inspection dates.
Bulk and cargo tank basics
- A bulk packaging has a maximum capacity greater than 119 gallons for a liquid, greater than 882 pounds net mass and greater than 119 gallons capacity for a solid, or greater than 1,000 pounds water capacity for a gas (171.8). A 55-gallon drum is non-bulk; a 5,000-gallon cargo tank is bulk.
- Common highway cargo tanks: DOT-406 (MC-306) for flammable liquids, DOT-407 (MC-307) and DOT-412 (MC-312) for corrosives, DOT-331 (MC-331) for liquefied petroleum gas, and DOT-338 (MC-338) for cryogenic liquids. The specification plate shows the tank type, maximum allowable working pressure, and test dates.
- Cargo tanks require periodic external visual inspections and internal or pressure tests at intervals in Part 180-commonly every 5 years, with some tanks on shorter cycles. A missing or illegible specification plate is a defect; do not load the tank.
- Filling limits and outage: liquids must not be loaded so full that they become liquid-full at 55°C (131°F) (173.24b). Leave the required outage; gasoline and other volatile liquids expand with temperature.
- Baffles reduce surge. Smooth-bore tanks have no baffles and require slower stops, wider turns, and extra following distance. Tank vehicles have a high center of gravity, so rollover risk is high.
Worked example
A DOT-406 tank has a 9,000-gallon capacity and is rated for gasoline. The driver wants to fill it to the dome before a hot afternoon run. The correct decision is to leave outage according to the filling limit, not top it off. Liquid expansion could force product out the vent or damage the tank. The driver also verifies the specification plate and current test date before loading.
Traps
The 119-gallon number is capacity, not the amount loaded. A cargo tank endorsement is not the same as a hazmat endorsement. Do not assume any tank can carry any liquid; linings, gaskets, and specification limits matter. Do not ignore retest dates.