Boiler Operation, Maintenance, and Safety
Normal operation and abnormal conditions
Startup: verify water level, open vents, warm up slowly, purge the furnace, prove flame, then raise pressure and cut in. Shutdown: reduce firing, blow down as appropriate, and cool at a controlled rate. Layup: wet layup (flooded with treated, deaerated water plus an oxygen scavenger) for short idle periods; dry layup with desiccant for long or freezing conditions.
Safety systems exist to be respected: lockout/tagout before working on rotating or electrical equipment, confined-space permits with atmospheric testing before drum or furnace entry, hot-work permits near fuel systems, and absolutely no bypassing of low-water cutoffs or flame safeguards.
Emergency response. Low water: if no water shows in the gauge glass, secure the fuel immediately and do not feed water into a hot boiler until it has cooled; follow the plant's written procedure. High water or carryover: reduce firing, blow down the surface, check the feedwater control. Tube failure: secure the fuel and keep feedwater on only if it can be maintained safely while shutting down. Power failure: close the main steam stop and watch the water level.
Traps
"Add water immediately" is almost always wrong when a low-water condition may have uncovered the crown sheet or tube sheet; the exam wants fuel secured first and the boiler cooled.
Rule of thumb
Never trust a single indication. A stuck low-water cutoff, a dirty gauge glass, and a failed level control all read normally until they don't - confirm with try cocks and a second device.