Safety Devices, Emergencies, and Accident Prevention
The protective chain
Know the function and failure mode of each device: safety valve (overpressure), low-water fuel cutoff (low water), high steam pressure limit, high temperature limit on hot water boilers, flame safeguard and fuel shutoff valves, low gas pressure and low oil pressure switches, and the rupture disc or relief device on the fuel train. Each is a last line of defense - jumping, wiring, blocking, or bypassing any of them is cause for immediate shutdown and license action. Test what you can safely test, per the manufacturer's method, and record it.
Emergencies
- Low water: stop the fuel, do not add water to a hot, possibly overheated boiler, cool and inspect.
- Burning fuel outside the furnace or a fuel leak/fire: trip the emergency stop, isolate the fuel at the manual valve, ventilate, evacuate, call for help.
- Tube rupture or water hammer: secure firing, isolate, let pressures equalize; water hammer usually means slugs of condensate or a valve opened too fast.
- Power failure: fuel valves must close on loss of power; steam-driven feed may be the only feed source.
Preventing the accident
Lockout/tagout before maintenance, proper PPE, confined-space entry procedure for drum and firebox entry, blocked-open or blocked-closed valve discipline, and a clean, well-lit boiler room. Every boiler needs a clearly marked, reachable emergency shutdown.
Rule of thumb: in doubt, shut down and ask. Any boiler can be re-fired; a person cannot be replaced.