Which of the following is NOT a proper step when testing a tank for leaks?

Using a gauge with an unlimited rating is not a proper step when testing a tank for leaks because the gauge must have an appropriate range that allows for accurate monitoring of pressure changes within the tank. Gauges that are not specifically rated for the expected pressure levels may lead to inaccurate readings or even damage due to under- or over-pressurization. Proper leak testing typically requires the use of gauges that provide clear indications of pressure changes within the operational limits of the system being tested, ensuring safety and reliability in identifying potential leaks.

In leak detection scenarios, applying pressure and soaping surfaces, inspecting for bubbles, and monitoring pressure changes over time are all standard practices that help operators identify leaks effectively. These methods allow for visual inspection and quantifiable data that can indicate the integrity of the storage tank.