What is the purpose of cargo residue sampling during tank cleaning?

• A. To confirm all water has been drained.
• B. To measure cleaning solvent consumption.
• C. To determine the tank's structural integrity.
• D. To verify residual content meets cargo specifications and to ensure no cross-contamination.

Answer: (D)

The key idea here is verifying what remains in the tank after cleaning to protect the next cargo and meet specifications. Residue sampling checks the amount and type of material left in the tank, ensuring it is within the limits set by the next cargo’s quality and compatibility requirements. By taking representative samples from different areas and depths, you can determine if there’s any cross-contamination or residue that could affect product quality, regulatory compliance, or cargo acceptance. If the residue levels don’t meet the specified limits, the tank may need additional cleaning before loading the next cargo.

This isn’t about confirming that water has been drained, measuring how much cleaning solvent was used, or assessing the tank’s structural integrity, which are separate considerations.