MI Boiler Operator flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

ASME Section I scope

Covers power boilers and high-temperature water boilers exceeding 15 psig steam or 160 psig water, including their appurtenances, and sets construction, material, and stamping requirements.

ASME Section IV scope

Covers heating boilers limited to 15 psig steam and 160 psig water at 250 degrees Fahrenheit, plus potable water heaters and related controls and relief devices.

MAWP definition

Maximum allowable working pressure is the highest pressure at which the weakest pressure part of the boiler may lawfully operate, based on design thickness and material strength.

Hydrostatic test pressure

For new construction the hydrostatic test is generally 1.5 times the maximum allowable working pressure, with air vented, safety valves isolated, and all joints visible for leak inspection.

Firetube vs watertube

In a firetube boiler hot gases pass through tubes surrounded by water; in a watertube boiler water passes through tubes surrounded by hot gases, allowing higher pressure and faster response.

Bottom blowdown purpose

Bottom blowdown discharges water from the lowest point to remove sludge and suspended solids, and is performed as short frequent blows with the burner firing only as permitted.

Surface blowdown purpose

Surface or continuous blowdown draws water from the steam-water interface to control dissolved solids, alkalinity, and foaming, with rate set by conductivity or chloride testing.

Low-water cutoff test

The low-water fuel cutoff is tested with the burner firing to confirm it shuts off fuel, not just alarms, and that the water column and gauge glass connections are clear.

Warm-up thermal stress

A cold boiler is warmed with limited firing rate so shell, tube sheet, and drum temperatures rise gradually, avoiding differential expansion that cracks seams and tube joints.

Water hammer cause

Water hammer is the banging caused by steam contacting accumulated condensate; drip legs, traps, and draining lines during warm-up prevent it and protect piping and fittings.

Safety valve pop test

A pop test verifies the safety valve opens at its set pressure and reseats; the valve is lifted by raising boiler pressure under controlled conditions and the result is logged.

Flame failure response

On loss of the flame signal the flame safeguard must close the fuel valves within the code flame-failure response time and require a full purge before any restart attempt.

Trial for ignition

The trial for ignition is the limited time the pilot or main burner may receive fuel while proving flame; exceeding it without a signal requires fuel shutoff and purge.

Pre-purge requirement

Before ignition, the furnace and passes are purged with air at the required flow for a set time to clear combustible gases, preventing furnace explosion on lightoff.

Operating vs limit control

Operating controls modulate firing within the normal range; limit controls are independent high-limit devices set above operating range and below safety valve setpoint to force shutdown.

Combustion air proving switch

A pressure or flow switch proves combustion air before and during firing, interlocked with the programmer so no fuel can enter the furnace without adequate airflow.

Gauge glass blowdown

Blowing the gauge glass confirms both upper and lower connections are open; a closed connection gives a false level and can hide a dangerous low-water condition.

NBIC R-stamp

The National Board Inspection Code governs in-service repairs and alterations; an R-stamp holder is authorized to repair or alter pressure parts and register the work.

ASME CSD-1 purpose

CSD-1 sets requirements for controls and safety devices on automatically fired boilers, covering flame safeguard, low-water cutoff, and limit controls, and is often adopted locally.

NFPA 85 scope

NFPA 85 addresses combustion system hazards for boilers over 12.5 million Btu per hour, covering fuel trains, purge, interlocks, and furnace explosion prevention.

National Board registration

Boilers built to ASME code are registered with the National Board and stamped with the code symbol and registration number, enabling traceable inspection history.

Jurisdictional authority

State or local boiler inspection authorities set operating certificate requirements, inspection intervals, and operator licensing, which may exceed but cannot relax ASME construction rules.

Stoichiometric methane reaction

Complete combustion of methane is CH4 plus 2 O2 giving CO2 plus 2 H2O; theoretical air is about 9.5 pounds of air per pound of natural gas.

Excess air and O2

Excess air beyond theoretical ensures complete combustion; for natural gas about 15 percent excess air corresponds to roughly 3 percent oxygen in the flue gas.

Three T's of combustion

Temperature, turbulence, and time must all be sufficient; short residence time, poor mixing, or low temperature produces carbon monoxide and smoke instead of complete combustion.

Draft definition

Draft is the small pressure difference that moves combustion air into the furnace and flue gases out the stack, produced by stack effect or by forced or induced draft fans.

Gas train order

A typical gas train runs manual shutoff, regulator, low and high gas pressure switches, safety shutoff valves, and a leak test valve, all listed and sized for firing rate.

Combustion analyzer tuning

Firing rate is set at low, mid, and high fire using an analyzer; oxygen, carbon monoxide, and stack temperature confirm safe, efficient air-fuel ratio at each point.

Scale formation cause

Scale is precipitated calcium and magnesium hardness baked onto heating surfaces; it insulates tubes, raises metal temperature, and leads to overheating and tube failure.

Deaerator function

A deaerator heats feedwater and strips dissolved oxygen and carbon dioxide to limit corrosion; an oxygen scavenger such as sodium sulfite removes the remainder.

Cycles of concentration

Cycles of concentration express how many times makeup solids are concentrated in boiler water; blowdown is adjusted to hold dissolved solids below the established limit.

Caustic embrittlement

Caustic embrittlement is stress-corrosion cracking of stressed seams from concentrated alkaline boiler water; controlled pH, alkalinity, and phosphate treatment plus good circulation limit it.