What is the MAWP threshold that requires the installation of 2 gage glasses?

The correct threshold for the installation of two gage glasses is based on the Maximum Allowable Working Pressure (MAWP) of a boiler. For MAWP greater than 400 psi, regulations stipulate that two gage glasses must be installed to ensure accurate monitoring of water levels. This is a safety measure to prevent potential over-pressurization and ensure the safe operation of the boiler.

Boilers operating at higher pressures are at a greater risk for incidents if water levels are not adequately monitored. The two gage glasses provide redundancy, allowing for one to be in use while the other can serve as a backup. This dual-monitoring system enhances safety protocols, ensuring operators can verify water levels reliably.

Other thresholds, such as those below 400 psi, do not typically require this additional safety measure, as one gage glass is deemed sufficient for maintaining safe operation at these pressures. Hence, the choice that specifies MAWP greater than 400 psi aligns with industry standards, reflecting the increased need for safety as boiler pressure rises.