OK 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 generating steam above 15 psig or hot water above 160 psig and 250 degrees F. Sets rules for design, materials, fabrication, and stamping.

Maximum allowable working pressure

The highest pressure at which a boiler or pressure part may operate, determined by the weakest component. Safety valves may not be set above this value.

Lowest permissible water level

The minimum water level at which the boiler may be safely operated, set at least 3 inches above the highest heating surface. The low-water cutoff must be mounted at or above this line.

Firetube vs watertube

Firetube boilers pass hot combustion gases through tubes surrounded by water. Watertube boilers pass water through tubes surrounded by hot gas and respond faster to load changes.

Blowoff valve arrangement

Two valves in series on the blowoff line: a quick-opening valve at the boiler and a slow-opening valve downstream. Piping must be at least Schedule 80 steel.

Fusible plug

A plug with a low-melting alloy installed in the crown sheet of a firetube boiler. It melts at about 445 degrees F to warn of low water.

Siphon on pressure gauge

A pigtail-shaped tube that traps condensate between the steam and the gauge, protecting the Bourdon tube from live steam temperature and keeping the gauge accurate.

Three-way gauge glass valve

A valve arrangement that allows the gauge glass to be blown down and then re-established without taking the boiler out of service, confirming the glass is not plugged.

Safety valve blowdown

The pressure drop below the set pressure at which a safety valve reseats, usually 2 to 4 percent for Section I valves. Excessive blowdown can waste steam.

Steam trap failure modes

A trap that fails open wastes live steam and raises fuel cost. A trap that fails closed backs up condensate and can cause water hammer and poor heating.

Furnace draft reading

Measured in inches of water column, with 1 inch w.c. about 0.036 psi. A normal high-fire furnace draft is roughly negative 0.05 to negative 0.10 inches.

Conductivity blowdown control

Blowdown rate equals feedwater TDS divided by maximum allowable TDS, minus one. This keeps dissolved solids below the level that causes carryover and scale.

Deaerator function

Removes dissolved oxygen and other gases from feedwater by heating it and scrubbing with steam. Oxygen pitting is prevented by deaeration plus a sulfite residual.

Scale thermal penalty

Scale insulates the tube surface, so heat cannot reach the water efficiently. Even a thin layer raises fuel consumption and can overheat tube metal.

Bottom vs surface blowdown

Bottom blowdown removes sludge and settled solids from the lowest point. Surface blowdown removes dissolved solids concentrated at the water surface.

Stoichiometric air

The exact amount of air needed for complete combustion of a fuel. Practical firing uses excess air above this to ensure all fuel burns.

Three T's of combustion

Temperature, turbulence, and time. All three must be sufficient; a deficiency in any one produces carbon monoxide and unburned fuel.

Furnace purge requirement

Before every light-off, the furnace must be purged with air, typically for five air changes at high fire, to clear any accumulated combustible gases.

Burner turndown ratio

The ratio of maximum firing rate to minimum stable firing rate. A packaged gas burner commonly achieves about 10 to 1 turndown.

Flame failure response

If the flame scanner loses the flame signal, the burner management system must shut off fuel within the trial-for-ignition time and lock out until manually reset.

Cold boiler warm-up rate

A cold boiler is warmed slowly, typically no faster than about 100 degrees F per hour, to avoid thermal stress on the shell, tubes, and tube sheets.

Air cock during warm-up

Opened on a cold boiler so air and non-condensable gases escape as steam forms. Closed once steam appears, before the boiler pressurizes.

Bringing boiler on line

Warm the boiler, raise pressure slightly above header pressure, then slowly open the main steam stop valve to equalize with the header without water hammer.

Thermal shock risk

Adding cold feedwater to a hot, low-water boiler can crack tubes and tube sheets. Feedwater should be added gradually and at a temperature close to boiler water.

Low-water cutoff test

Lower the water level in the float chamber or simulate the condition to confirm the burner shuts off. A manual-reset device must be reset only after the cause is corrected.

Flame safeguard sequence

Purge, trial for ignition, main flame proving, and post-purge. A lockout after flame failure requires manual reset before another light-off attempt.

Hydrostatic test pressure

For Section I boilers the test pressure is 1.5 times the maximum allowable working pressure. Safety valves are removed or gagged during the test.

Ultrasonic tube thickness

Measures remaining wall thickness of boiler tubes. Tubes must be replaced when the wall falls below the minimum allowed by the code.

Waterside inspection

Checks the water side for pitting, scale, and corrosion, especially at tube sheets and staybolts. Fireside inspection checks for soot, refractory damage, and tube bulging.

Oklahoma boiler program

The Oklahoma Department of Labor administers boiler safety under the Oklahoma Administrative Code, Title 380, including inspection and certification requirements.

Certificate of inspection

Issued after a satisfactory inspection and must be posted near the boiler. A boiler may not be operated with an expired certificate.

Out-of-service order

An inspector may order a boiler out of service for unsafe conditions. Operating it after that order is a violation subject to enforcement action.