NM Boiler Operator flashcards
NM Boiler Operator · 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.
- ASME Section I
- Covers power boilers and high-temperature water boilers operated above 15 psig steam pressure; it sets construction, material, welding, inspection, and stamping requirements.
- ASME Section IV
- Covers heating boilers limited to 15 psig steam or 160 psig and 250°F water; rules address construction, relief valves, and installation.
- S stamp
- ASME Code symbol stamped on a power boiler built to Section I; the Manufacturer's Data Report documents design, materials, and tests.
- H stamp
- ASME Code symbol for a heating boiler built to Section IV; it signifies compliance with heating-boiler construction and inspection rules.
- MAWP
- Maximum allowable working pressure marked on a boiler; the lowest-rated pressure part or component establishes the limit for operation and safety-valve setting.
- Hydrostatic test
- Pressure test using water, commonly 1.5 times MAWP for new ASME power boilers; it checks strength and tightness before service.
- NBIC R stamp
- Symbol used by qualified repair organizations for repairs or alterations to ASME-stamped boilers and pressure vessels under the National Board Inspection Code.
- Boiler horsepower
- Heat rate equal to 33,475 Btu per hour, roughly 34.5 pounds of steam per hour evaporated from and at 212°F.
- Latent heat
- Heat absorbed or released during a phase change at constant temperature; for saturated steam it decreases as pressure rises and is zero at the critical point.
- Pre-purge
- Controlled airflow through the furnace and flue before ignition to remove combustible gases; typically four to eight furnace volume changes.
- Low-water trip
- Safety action that stops fuel firing when water level falls below the safe limit; water must not be added to an overheated boiler until it cools.
- Normal boiler shutdown
- Reduce firing, stop the burner, keep feedwater available, and allow controlled cooldown; do not drain a hot boiler until pressure and temperature are safe.
- Saturated steam
- Steam at the boiling-point temperature for its pressure, containing no superheat; its temperature and pressure are fixed together in the saturated state.
- Stoichiometric air
- Minimum air theoretically needed for complete combustion; natural gas requires about 9.5 to 10 cubic feet of air per cubic foot of gas.
- Excess air
- Air supplied beyond stoichiometric requirements; typical values are 5 to 10 percent for gas, 10 to 15 percent for oil, and 15 to 25 percent for coal.
- Flame safeguard
- Control system that proves pilot or main flame and closes fuel valves within a set time if flame is lost, preventing fuel accumulation in the furnace.
- Forced draft
- Combustion-air fan located upstream of the burner that pushes air into the furnace; it must overcome burner and furnace resistance.
- Induced draft
- Fan downstream of the boiler that pulls flue gas through the unit and maintains negative furnace pressure; it handles hot, dirty gas.
- Burner turndown
- Ratio of maximum firing rate to minimum stable firing rate; excess air, flame stability, and emissions limit the achievable turndown.
- Deaerator
- Feedwater heater that removes dissolved oxygen and other gases by heating water and venting the gases; it reduces corrosion pitting in the boiler.
- Oxygen scavenger
- Chemical such as sodium sulfite or hydrazine added to feedwater to remove residual dissolved oxygen after deaeration and protect metal surfaces.
- Scale
- Deposit mainly of calcium and magnesium salts on waterside surfaces; it insulates metal, reduces heat transfer, and can overheat tubes.
- Continuous blowdown
- Controlled blowdown from the boiler water surface to limit dissolved solids and foam; rate is set from feedwater and boiler-water TDS limits.
- Bottom blowdown
- Short, controlled blowdown from the lowest point to remove sludge and sediment; two valves in series are used for safety.
- Water hammer
- Pressure surge caused by steam condensing or fast valve closure; condensate drains and traps prevent it in steam lines.
- Softener
- Ion-exchange unit that replaces calcium and magnesium hardness with sodium; it prevents scale but does not remove dissolved solids.
- Low-water fuel cutoff
- Required safety device that senses low water and stops fuel firing; its chamber and linkages must be kept clean and tested.
- Safety valve
- Automatic pressure-relief device that opens at set pressure and closes after pressure drops; its capacity must equal or exceed boiler steam output.
- Gauge glass
- Water-level indicator connected to the boiler with upper and lower fittings; it must be kept clear and protected by shields.
- Three-way gauge cock
- Valve fitting that allows a pressure gauge to be isolated, vented to zero, or connected to the boiler through a siphon.
- NM Mechanical Safety Bureau
- New Mexico office that administers boiler and pressure-vessel safety, adopts ASME and NBIC codes, and issues inspection certificates.
- Certificate to operate
- Document issued after required inspection shows a boiler may be operated; it must be posted and kept current under New Mexico rules.