In a hydrostatic test of a standpipe where the maximum pressure is in excess of 150 psi, what pressure value is added to the maximum pressure to establish the hydrostatic test pressure?

• A. 25
• B. 50
• C. 100
• D. 150

Answer: (B)

Hydrostatic testing checks that the piping and fittings can hold up under pressure higher than normal service without leaking. When the standpipe’s maximum operating pressure is greater than 150 psi, the test pressure is set by adding 50 psi to that maximum. This 50 psi cushion provides a reliable margin to reveal leaks or weak joints while staying within typical component pressure ratings. For example, if the maximum pressure is 180 psi, the hydrostatic test pressure would be 230 psi. The other options don’t provide the standardized margin required for these higher-pressure systems.