In hydrostatic testing of a standpipe with high maximum pressure, what is the numerical value added to establish the hydrostatic test pressure?

• A. 25 psi
• B. 50 psi
• C. 100 psi
• D. 150 psi

Answer: (B)

Hydrostatic testing uses a test pressure that exceeds the system’s normal operating pressure to reveal leaks and weaknesses in the piping, joints, and fittings. For standpipes that operate at very high maximum pressures, a fixed margin is added to that maximum to set the test pressure. In this case, the standard practice is to add 50 psi to the highest design pressure.

This 50 psi increment provides enough margin to uncover potential leaks without pushing components beyond what their ratings can safely handle during the test. It ensures the system can tolerate a pressurized condition that’s clearly above normal operation, so defects become evident, while staying within practical and equipment-rated limits. Other values would either underload the test, risking missed defects, or push the system beyond safe limits, which is why 50 psi is the chosen figure.