BD First Class Boiler Attendant flashcards
BD First Class Boiler Attendant · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Maximum allowable working pressure
- The highest pressure at which a boiler or pressure part may be operated, determined by design calculations and stamped on the boiler nameplate; exceeding it is prohibited.
- Certificate of inspection
- A document issued after a satisfactory statutory inspection that authorises boiler operation until a stated expiry date; operation after expiry is unlawful.
- Water-tube boiler
- A boiler in which water circulates inside tubes surrounded by hot combustion gases, allowing high pressure and rapid steam generation with smaller drum volume.
- Fire-tube boiler
- A boiler in which hot gases pass through tubes immersed in water within a cylindrical shell, giving large water storage but lower pressure capability.
- Staying
- The use of stay bolts and stay tubes to tie flat or unsupported surfaces against pressure loads; broken stays can lead to catastrophic failure of the plate.
- Safety valve
- A spring-loaded valve that opens automatically at a set pressure to discharge steam and prevent overpressure; its setting must not exceed the maximum allowable working pressure.
- Low-water fuel cutoff
- A device that senses water level and shuts off the fuel supply when the level falls below a safe limit, preventing overheating of the crown sheet or tubes.
- Fusible plug
- A plug with a low-melting alloy fitted in the crown sheet; when water uncovers it, the alloy melts and releases steam into the furnace as a warning.
- Gauge glass
- A transparent tube connected to the boiler at steam and water level, showing the true water level; its lowest visible point must be above the lowest permissible level.
- Excess air
- Air supplied beyond the theoretical amount needed for complete combustion, typically 10 to 20 percent, to ensure all fuel burns and reduce carbon monoxide formation.
- Flame failure device
- A control that monitors the burner flame and closes the fuel valve within a set safety time if the flame is lost, preventing fuel accumulation and explosion.
- Atomisation
- The breaking of fuel oil into fine droplets by pressure or steam/air so it mixes readily with air; poor atomisation causes smoke and carbon deposits.
- Furnace purge
- A forced flow of air through the furnace before light-off to remove any accumulated combustible gases, preventing ignition explosions on start-up.
- Priming
- The carryover of boiler water droplets into the steam outlet, caused by high water level, foaming, or sudden load change, leading to water hammer and contamination.
- Blowdown
- The controlled discharge of boiler water to remove dissolved solids and sludge; performed at low fire with the water level high to avoid loss of level.
- Caustic embrittlement
- A form of stress-corrosion cracking of steel caused by concentrated alkaline boiler water in seams and crevices, controlled by limiting caustic alkalinity.
- Oxygen scavenger
- A chemical such as sodium sulphite or hydrazine added to feedwater to remove dissolved oxygen and prevent pitting corrosion of steel surfaces.
- Scale
- A hard deposit of calcium and magnesium salts on heating surfaces that insulates the metal, reduces heat transfer, and can cause overheating and tube failure.
- Superheated steam
- Steam heated above its saturation temperature at a given pressure, improving cycle efficiency and reducing condensation losses in engines and turbines.
- Economiser
- A heat exchanger that recovers heat from flue gas to preheat feedwater before it enters the boiler, improving overall thermal efficiency.
- Deaerator
- A vessel that heats feedwater to saturation and vents released gases, removing dissolved oxygen and carbon dioxide to limit corrosion in the feed system.
- Hydrostatic test
- A pressure test using water, typically at 1.25 to 1.5 times the maximum allowable working pressure, to verify the strength and tightness of pressure parts.
- Ultrasonic thickness testing
- A non-destructive method using high-frequency sound to measure remaining wall thickness of tubes and plates, determining whether corrosion has reduced strength below limits.
- Confined space entry
- Entry into a boiler drum or furnace under an isolation, lockout, ventilation, and atmospheric testing permit to protect against oxygen deficiency and toxic gases.
- Water hammer
- A sharp pressure surge caused by steam meeting condensate or by rapid valve movement; it can crack pipes and fittings and is prevented by slow valve operation and draining.
- Boiler explosion energy
- The destructive energy released when pressurised water suddenly flashes to steam; most stored energy resides in the water volume rather than the steam space.
- Low-water condition
- A state where the water level falls below the safe limit, exposing heating surfaces; the correct response is to cut off fuel immediately and never add water.
- Three-element feedwater control
- A control strategy using drum level, steam flow, and feedwater flow signals to maintain water level during load changes while compensating for level swell.
- Flue gas oxygen analysis
- Measurement of oxygen in the flue gas to indicate excess air level; high oxygen means excess air and wasted heat, low oxygen risks incomplete combustion.
- Stack loss
- The heat carried away by flue gases leaving the boiler, the largest efficiency loss; it increases with stack temperature and excess air.
- Heat balance
- An accounting of heat input versus useful steam output and losses, used to identify where efficiency is lost in a boiler plant.
- Try cocks
- Small valves fitted at high, normal, and low water levels on the boiler shell, used to verify water level if the gauge glass is blocked or unreliable.