What is the function of a boiler safety valve and when does it operate?

• A. It is a pressure-relief device set to the maximum allowable working pressure; it opens automatically to vent steam and prevent overpressure.
• B. It regulates feedwater level automatically.
• C. It reduces water level automatically.
• D. It purges ash from furnace.

Answer: (A)

The function of a boiler safety valve is to protect the boiler from overpressure. It is set to the maximum allowable working pressure and stays closed during normal operation. If the steam pressure rises to that set point, the valve automatically opens to vent steam, relieving enough pressure to keep the system within safe limits. Once the pressure drops below the reseating level, the valve closes again. This device is not used to regulate pressure during normal operation, nor does it affect water level or ash handling. It acts as a last-resort safety release to prevent dangerous overpressure conditions.