A non-insulated, single-shell vessel carrying liquefied gases is an:

• A. MC 338
• B. MC 306
• C. MC 312
• D. MC 331

Answer: (D)

A tank that is non-insulated and single-shell is designed for liquefied gases that are kept under pressure rather than cryogenic temperatures. This type of cargo tank is classified as MC-331. MC-331 tanks are large-capacity, non-pressurized (or low-pressure) tanks used to transport liquefied gases such as propane, butane, and ammonia, and they do not have the insulation or the double wall found on cryogenic or refrigerated tanks.

MC-338 describes cryogenic, insulated tanks for ultra-low-temperature liquids; MC-306/406 are non-pressurized tanks for flammable liquids (not gases); MC-312/412 are pressure cargo tanks (often insulated and designed for liquids under higher pressure). The non-insulated, single-shell design specifically aligns with MC-331.