Which of the following actions is essential for boiler operators before starting operations?

Checking water levels is crucial for boiler operators before starting operations because maintaining the correct water level is vital for the safe and efficient functioning of a boiler. If the water level is too low, it can lead to overheating and damage to the boiler, potentially causing a catastrophic failure known as "dry firing." Conversely, if the water level is excessively high, it can lead to water carryover into the steam system, resulting in water hammer and erosion of components.

Monitoring the water level also ensures that there is sufficient water to absorb the heat generated by the combustion process, which prevents overheating and allows for the appropriate steam generation. This is especially important in high-pressure systems where the margin for error is significantly reduced.

While inspecting insulation, calibrating tools, and greasing moving parts are important maintenance practices that contribute to the overall efficiency and safety of boiler operations, they do not specifically address one of the most critical factors that need to be checked before the boiler is energized. Proper water level management directly impacts the operation's safety and effectiveness, making it the primary concern for operators prior to starting the boiler.