Which of the following are identifying features of the DOT 406 cargo tank?

• A. Large oval ends; Underbelly outlets; spill rail
• B. Large oval ends
• C. Underbelly outlets
• D. Spill rail

Answer: (A)

Identifying features of the DOT 406 cargo tank come from recognizing a specific combination of design elements that set this tank type apart. First, you’ll notice large oval ends. This rounded, elongated end shape is a hallmark of the DOT 406 design and helps distinguish it from other tank configurations. Second, there are outlets located on the underside of the tank—underbelly outlets. These bottom-side discharge openings are characteristic of this non-pressurized tanker and are used for gravity-fed loading and unloading. Third, a spill rail runs along the top edge of the tank. This rail helps contain any liquid spills during loading or unloading, providing a simple safeguard feature.

When these three features appear together—large oval ends, underbelly outlets, and a spill rail—you can identify a DOT 406 cargo tank. While some tanks may show one or two of these features, the combination of all three is what uniquely points to the DOT 406 type.