Boiler Operation, Startup, and Shutdown Procedures
Boiler Operation, Startup, and Shutdown Procedures
This domain tests safe sequencing: pre-start inspection, purge, light-off, warm-up, normal operation, and planned or emergency shutdown. The examiner looks for order and interlock discipline, not speed.
Before light-off
Confirm water level in the gauge glass, open vents on a cold boiler, verify fuel supply and draft, check the burner and flame scanner, and prove the low-water cutoff and high-limit. Confirm the boiler is vented and isolated from the steam header until warm. For gas or oil, ensure the combustion air openings are clear.
Light-off and warm-up
Start the forced/induced draft fan, prove airflow, and purge the furnace and breeching for the required time. Light the pilot, prove the pilot flame, then open the main fuel valve at low fire. Warm a cold boiler slowly; a steam boiler may need one to two hours or more depending on size and temperature. Close vents only after steam forms, then bring pressure up gradually and warm the header before opening the main stop valve.
Shutdown
For a planned shutdown, reduce firing, stop the burner, purge, close the fuel valve, and maintain water level as the boiler cools. Do not dump a hot boiler. For an emergency, trip the burner, close fuel, and isolate only as conditions permit; keep feedwater available if the boiler is still hot.
Worked example
A cold steam boiler is filled to normal level, vents open, LWCO tested, and purge completed. The operator lights the pilot, proves it, and fires at low rate. Pressure rises to 15 psig; the operator warms the header and opens the stop valve slowly. The reasoning: slow warming limits thermal stress and water hammer; opening the header valve too fast can collapse steam and damage piping.
Traps
Skipping purge, bypassing flame safeguards, lighting with low water, closing vents before steam, or adding cold water to an overheated empty boiler are mark-losing errors. Never leave a boiler unattended during light-off.