What action is critical when loading petroleum cargo at low temperatures?

When loading petroleum cargo at low temperatures, ensuring space for cargo expansion is crucial due to the physical properties of liquids. As petroleum products are loaded at lower temperatures, they may not behave in the same way as they would at higher temperatures, which can lead to an increase in volume during the loading process. If the cargo expands and there is insufficient space in the tank, it can lead to serious safety hazards such as overflow, spillage, or the potential for tank rupture.

Additionally, petroleum products can vaporize and expand in volume as temperature changes, especially during the heating process that may occur after loading. Therefore, accommodating for potential expansion is a key factor in ensuring safe loading practices and preventing environmental contamination.

While checking for leaks, verifying insulation, and maintaining vapor pressure are also important steps in the loading process, the key focus at low temperatures specifically revolves around managing the expansion of the cargo to prevent overflow and subsequent risks.