When should a tank not be subjected to the installation air/soap test?

The correct choice highlights a critical safety and procedural consideration in tank management. A tank should not undergo the installation air/soap test when liquid-filled interstices are present because these areas can trap liquid and create a false sense of security regarding the integrity of the tank. The presence of liquid in interstices can interfere with the test's ability to accurately identify leaks or weaknesses since the soap solution may not be able to reach areas where liquid has collected.

Testing tanks with liquid present could lead to incomplete assessment, and any potential leaks might go undetected, posing safety risks and environmental hazards. It’s essential that the tank and its interstices are free from any liquid before conducting such tests to ensure accurate evaluations of the tank's integrity and prevent incidents during operation.

This understanding emphasizes the need to evaluate not only the physical condition of the tank but also its operational context during testing procedures.