Boiler Operation and Maintenance
Domain 2 - Boiler Operation and Maintenance. This domain tests routine operation, water-level discipline, blowdown, layup, and the maintenance that keeps tubes clean and inspections passing.
Startup and water level
Warm a cold boiler slowly and keep the burner at low fire until the shell or drum expands evenly. The gauge glass is the operator's primary instrument: prove it by blowing down and watching the water return, then compare with the try cocks. Bottom blowdown is done under light load: open the quick-opening valve first, then the slow-opening valve, and close in reverse order. Skimming removes oil, foam, and sludge from the surface.
Routine maintenance
Clean tubes and firesides on schedule - soot and scale are insulation that raises stack temperature and fuel use. Inspect refractory, gaskets, and handhole plates at every outage. Test the low-water fuel cutoff and safety-valve try lever as rules and manufacturer instructions require, and log the results. Wet layup uses treated, deaerated water with an oxygen scavenger and a nitrogen blanket; dry layup uses desiccant with the boiler sealed.
Worked example
A 100 hp boiler evaporates about 3,450 lb/h (1 hp = 34.5 lb/h). At 5 percent blowdown, blowdown flow = 3,450 × 0.05 = 172.5 lb/h, or about 4,140 lb/day. The operator uses that figure to set blowdown duration and to confirm that TDS is actually controlled rather than guessed at.
Traps
Blowing down a boiler that is already low on water; adding water to a hot, overheated boiler before it cools; opening the slow-opening valve before the quick-opening valve; trusting a gauge glass that has not been proven; skipping fireside cleaning because the stack looks fine.