California ICC UST Inspector Practice Exam

Upon installation, all new primary piping and secondary containment systems of USTs must be tested for tightness hydrostatically at what design operating pressure?

1. 100% operating pressure

2. 150% operating pressure

3. 110% operating pressure

4. None of the above

The correct answer is: 150% operating pressure

The correct answer is based on the standard practice for testing the integrity and safety of underground storage tanks (USTs) and their associated systems. Tightness testing via hydrostatic means is crucial to ensure that there are no leaks in the primary and secondary containment systems once they are installed. Testing at 150% of the design operating pressure is essential because it provides a safety margin greater than the normal operating conditions. This extra pressure helps to identify any weaknesses or leaks that could lead to contamination or failure under normal operational stress. By ensuring that the system can withstand pressures beyond what it will typically experience, this testing method fosters a higher level of safety and compliance with regulatory standards. The other choices do not meet the industry’s accepted safety margins. For instance, testing at 100% operating pressure might not adequately reveal potential weaknesses, while testing at 110% may not provide enough of a buffer for safety. Therefore, the requirement to test at 150% operating pressure reflects best practices aimed at safeguarding the environment and public health from potential hazards associated with UST systems.