When should safety valve gages be placed on the boiler before setting safeties?

The correct answer is based on the importance of ensuring that safety valve gauges are accurately reflecting pressure conditions before the safety valves are set. Placing the gauges when the steam drum pressure is 100 to 200 psi below the lowest safety valve setting is critical because it allows for an accurate assessment of the safety system's performance.

This practice ensures that the valves can be properly tested, as they should only start to release steam at or above their designated pressure setting. By establishing this pressure threshold, technicians can verify that the safety valves operate correctly and maintain boiler safety without risking premature valve operation or false settings. It provides a margin that confirms the valve will function as intended within its designed safety parameters.

Other options may suggest scenarios that do not provide the optimal conditions for confidently assessing the safety of the boiler system. For example, setting valves at pressures significantly higher than the correct range might lead to unsafe conditions or inaccurate testing of the valves, failing to ensure their reliability in preventing overpressure situations.