Where should the soap solution be applied during an air/soap test?

The soap solution should be applied to the fitting joints and pipe surfaces during an air/soap test because these are the critical areas where leaks are most likely to occur. The fittings and joints are points of vulnerability in the piping system; they are the interfaces where different sections of pipes connect. These areas are often under stress from movement, temperature changes, or pressure fluctuations, making them prime candidates for leaks.

Applying the soap solution creates bubbles when there is a leak, making it easy to visually identify any escaping air. By focusing on the joints and surfaces that are prone to failure, technicians can efficiently detect leaks and take corrective actions as necessary. This method ensures the integrity of the entire underground storage tank system is assessed effectively.

Applying the soap solution to the entire surface of the pipe, only at the ends of the pipe, or on the trench walls would not provide a thorough assessment. While those areas may also be inspected, concentrating on the fitting joints and pipe surfaces is essential for detecting any leak that could compromise the UST system's safety and compliance.