What is NOT required of the cargo tank venting on a tank barge carrying grade A liquids?

Correct Answer: Option C — The diameter of the vent must be greater than 4 inches in diameter.

46 CFR regulations for tank barges carrying Grade A liquids do not mandate a vent diameter exceeding 4 inches. Vent sizing depends on maximum loading rates, tank capacity, and pressure drops, while pressure-vacuum valves and weather deck extension remain mandatory.