Minnesota Boiler License Practice Exam

One of the safety valves on the boiler proper shall be set:

1. At or below the maximum allowable working pressure

2. Not more than 6% above the maximum allowable working pressure

3. Not more than 10% above the maximum allowable working pressure

4. Not more than 15% above the maximum allowable working pressure

The correct answer is: At or below the maximum allowable working pressure

The correct answer is that one of the safety valves on the boiler proper shall be set at or below the maximum allowable working pressure. This is a critical safety measure designed to prevent overpressure situations in the boiler system. The maximum allowable working pressure (MAWP) is defined as the maximum pressure at which the boiler can safely operate, and safety valves are essential components that protect against excessive pressure build-up. Setting the safety valve at or below the MAWP ensures that if the pressure within the boiler exceeds this threshold, the valve will open and release steam or water, thus preventing potential failures, explosions, or catastrophic damage to the boiler or adjoining systems. It is crucial that safety valves are calibrated correctly to ensure they function reliably in protecting the system from pressure excursions. In contrast, other choices suggest allowing for pressures set above the MAWP, which could leave the boiler at risk during pressure surges. For instance, setting a safety valve not more than 6%, 10%, or 15% above the MAWP would compromise the safety integrity of the boiler because it could lead to a situation where the pressure exceeds safe operational limits before the safety valve activates. This would go against fundamental safety protocols in boiler operation.