This cargo container has a round or horseshoe-shaped tank and may be insulated. Which designation is this container?

• A. DOT 407
• B. DOT 406
• C. DOT 412
• D. DOT 380

Answer: (A)

A round or horseshoe-shaped cross-section is a hallmark of a non‑pressurized liquid cargo tank built for flammable liquids. This design is sturdy and simple, optimized for ambient-pressure operation, and insulation may be added to help maintain product temperature or reduce heat transfer. Those features point to the DOT designation for non‑pressurized liquid tankers used for flammable liquids. Other tank designs are built for different pressure ranges or cargoes and don’t share this same round/horsehoe shape with optional insulation, so they don’t fit as well. So the container described matches the DOT 407 designation.