Which pressure indicates that a safety valve must be maintained?

Safety valves are critical components in boiler systems, designed to prevent excessive pressure buildup by releasing steam or other gases when a predetermined pressure is reached. Understanding the different types of pressures associated with a boiler is essential for effective safety management.

The correct choice focuses on relief pressure, which is specifically the pressure setting at which the safety valve is designed to open and relieve excess pressure from the system. This indicates the maximum pressure at which the safety valve must function to prevent potential catastrophic failures. Proper maintenance of safety valves is necessary to ensure they operate correctly and open at the correct relief pressure, providing a vital safety mechanism to protect both the system and personnel.

In contrast, operating pressure refers to the normal pressure under which a boiler operates, while design pressure is the maximum intended pressure that the equipment can safely withstand during its operation without risk of failure. Gauge pressure is a measure of pressure relative to atmospheric pressure, often used in readings but does not specify the threshold for valve operation. These pressures do not dictate the maintenance of safety valves in the same way that relief pressure does.