California ICC UST Inspector Practice Exam

What is the minimum test pressure for hydrostatic testing?

1. 30 psi

2. 40 psi

3. 50 psi

4. 60 psi

The correct answer is: 40 psi

The minimum test pressure for hydrostatic testing of underground storage tanks (USTs) is typically set at 1.5 times the maximum allowable working pressure of the system, which ensures that all parts of the tank are thoroughly tested for leaks and structural integrity. While the specific value may vary depending on various factors, such as regulations and facility requirements, a common industry standard for the minimum test pressure is 40 psi. This pressure is designed to create a safety margin that accounts for any potential weaknesses or defects in the tank material or construction. Testing at 40 psi allows inspectors to reliably assess the tank's ability to contain liquids without leakage. It is important for compliance with safety regulations and environmental protection measures, as any leak can have significant implications for soil and water safety. In practice, a pressure of 30 psi might not be sufficient to adequately challenge the integrity of a typical UST, and anything above 50 psi could introduce unnecessary risk of damage or misinterpretation of tank performance. Therefore, selecting 40 psi as the minimum test pressure is aligned with established safety practices in the industry.