Bulk Packages, Cargo Tanks, and Portable Tanks
When volume rises, drums give way to bulk packagings, cargo tanks, and portable tanks. This domain tests the definitions, the tank types, and the operating rules that keep a tank from becoming a hazard on its own.
Bulk packaging definitions
A bulk packaging has a capacity greater than 119 gallons for liquids, more than 882 lb for solids, or more than 1,001 lb water capacity for gases. Smaller packagings are non-bulk and follow the marking and labeling rules instead of the bulk placarding rules.
Cargo tank types
- DOT 406 (MC 306) - flammable liquids, low pressure.
- DOT 407 (MC 307) - low-pressure chemicals and mild corrosives.
- DOT 412 (MC 312) - corrosives, built to a higher design pressure.
- DOT 331 (MC 331) - high-pressure liquefied gases such as LPG and anhydrous ammonia.
Each tank carries a specification plate, and a tank may only carry products it is designed and tested to hold.
Loading and moving tanks
- Leave the required outage (vapor space); never fill a tank liquid-full, because expansion can push liquid out of relief devices.
- Close and secure internal valves, external valves, domes, and outlets before moving.
- Ground and bond, and use vapor recovery where required.
- Cargo tanks need periodic inspection and testing under Part 180, including at least an annual external visual inspection and leak test.
Worked example
A driver tops off a DOT 406 gasoline tank until fuel stands in the fill dome. That is wrong: with no outage, a warm day can liquid-fill the tank and the relief valve will discharge liquid gasoline instead of vapor.
Traps
Assuming any tank can carry any liquid; loading with the engine running; moving with a valve open; treating the specification plate as decoration; ignoring the outage rule on partial loads.