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AK Boiler Operator practice questions

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Question 1Boiler Construction, Design, and Code Requirements

Which ASME Boiler and Pressure Vessel Code section contains the rules for construction of power boilers?

  1. Section VIII
  2. Section II
  3. Section IV
  4. Section I Correct answer.

Explanation

Section I, Rules for Construction of Power Boilers, governs boilers whose maximum allowable working pressure exceeds 15 psig. Section II supplies material specifications and allowable stresses, Section IV covers heating boilers, and Section VIII covers pressure vessels.

Question 2Boiler Construction, Design, and Code Requirements

A steam heating boiler is designed for a maximum allowable working pressure of 12 psig. Under which code section is it built?

  1. Section IV Correct answer.
  2. Section IX
  3. Section VIII, Division 1
  4. Section I

Explanation

Section IV applies to heating boilers limited to 15 psig steam or to 160 psig and 250 deg F water, so a 12 psig steam heating boiler falls within its scope. A boiler designed above 15 psig steam would be built to Section I.

Question 3Boiler Construction, Design, and Code Requirements

The ASME Boiler and Pressure Vessel Code is developed and published by which organization?

  1. The National Fire Protection Association
  2. The American Petroleum Institute
  3. The National Board of Boiler and Pressure Vessel Inspectors
  4. The American Society of Mechanical Engineers Correct answer.

Explanation

ASME writes and publishes the Boiler and Pressure Vessel Code. The National Board administers inspection, registration, and the NBIC, while NFPA and API publish unrelated standards.

Question 4Boiler Construction, Design, and Code Requirements

A newly constructed Section I boiler must be given a hydrostatic test at what pressure?

  1. 1.5 times the maximum allowable working pressure Correct answer.
  2. 1.25 times the maximum allowable working pressure
  3. 1.0 times the maximum allowable working pressure
  4. 2.0 times the maximum allowable working pressure

Explanation

PG-99 requires every new boiler to be hydrostatically tested at 1.5 times the maximum allowable working pressure before it is stamped and placed in service. The test verifies the pressure tightness and integrity of the completed boiler.

Question 5Boiler Construction, Design, and Code Requirements

The code symbol stamp applied to a new power boiler built to Section I is:

  1. U
  2. S Correct answer.
  3. R
  4. H

Explanation

The S stamp identifies a power boiler built to Section I. H marks a Section IV heating boiler, U marks a Section VIII pressure vessel, and R is the National Board stamp for repairs and alterations.

Question 6Boiler Construction, Design, and Code Requirements

Section I requires the total relieving capacity of the safety valves on a boiler to be at least equal to:

  1. The rated capacity of the feedwater pumps
  2. The normal plant steam demand plus 25 percent
  3. The main steam line design flow rate
  4. The boiler's maximum steam generating capacity Correct answer.

Explanation

The valves must be able to pass at least as much steam as the boiler can generate at maximum firing, so that pressure cannot run away if the load is lost. Total capacity of all valves installed is compared against the maximum evaporating capacity.

Question 7Boiler Construction, Design, and Code Requirements

Which ASME code section specifies acceptable material specifications and allowable stress values used in boiler design?

  1. Section V
  2. Section VI
  3. Section II Correct answer.
  4. Section IX

Explanation

Section II, Parts A through D, lists permitted material specifications, mechanical properties, and the allowable stress tables that Sections I and IV use in design calculations.

Question 8Boiler Construction, Design, and Code Requirements

Repairs and alterations to a boiler that is already in service are governed by which document?

  1. The National Board Inspection Code Correct answer.
  2. ASME Section VI, Recommended Rules for Care of Heating Boilers
  3. ASME Section VIII, Division 1
  4. ASME Section IX

Explanation

The National Board Inspection Code covers in-service inspection, repairs, and alterations and issues the R stamp to repair organizations. The ASME construction sections apply to new construction, although the NBIC references Section IX for welding qualification.

Question 9Boiler Construction, Design, and Code Requirements

Under Section I, a miniature boiler is limited to what maximum allowable working pressure?

  1. 50 psig
  2. 250 psig
  3. 100 psig Correct answer.
  4. 15 psig

Explanation

A miniature boiler is a Section I power boiler with an inside diameter not over 16 in., gross volume not over 5 cu ft, heating surface not over 20 sq ft, and a maximum allowable working pressure not over 100 psig; it carries the M stamp.

Question 10Boiler Construction, Design, and Code Requirements

A boiler has a maximum allowable working pressure of 250 psig. What is required for its blowoff connection?

  1. Two valves in series, one of them slow-opening Correct answer.
  2. Two valves in series, both quick-opening
  3. A single slow-opening valve
  4. A single valve with a plugged tee downstream for draining

Explanation

Where the maximum allowable working pressure exceeds 100 psig, Section I requires two blowoff valves in series, one of which must be a slow-opening valve. The two-valve arrangement allows the outer valve to be serviced while the inner valve holds pressure.

Question 11Boiler Construction, Design, and Code Requirements

Section I requires that the lowest visible part of a boiler water gage glass be located:

  1. At least 2 in. above the lowest permissible water level Correct answer.
  2. At least 4 in. above the lowest permissible water level
  3. At least 1 in. above the lowest permissible water level
  4. At the lowest permissible water level

Explanation

The gage glass must show the water level down to a point at least 2 in. above the lowest permissible water level. This gives the operator a visible warning band before the water drops to the unsafe limit.

Question 12Boiler Construction, Design, and Code Requirements

Section I requires that each boiler be provided with:

  1. A single feed pump sized for 125% of boiler capacity
  2. Two separate water columns
  3. At least two means of feeding water Correct answer.
  4. An automatic feedwater regulator on every boiler

Explanation

Every boiler must have at least two independent means of supplying feedwater so that failure of one source does not leave the boiler without feed. The second means may be a standby pump or another independent supply arrangement recognized by the code.

Question 13Boiler Construction, Design, and Code Requirements

Welding procedure specifications and welder performance qualifications for boiler construction are governed by:

  1. Section II, Part C
  2. Section V
  3. Section IX Correct answer.
  4. Section I, Part PW

Explanation

Section IX contains the rules for qualifying welding procedures and the performance of welders and welding operators. Section I invokes Section IX and adds its own requirements for joint design, heat treatment, and examination.

Question 14Boiler Construction, Design, and Code Requirements

Which ASME code section covers nondestructive examination methods such as radiography and ultrasonic examination?

  1. Section VIII
  2. Section III
  3. Section IX
  4. Section V Correct answer.

Explanation

Section V describes radiographic, ultrasonic, magnetic particle, liquid penetrant, and visual examination methods together with their techniques and acceptance standards. Sections I and IV reference Section V when examination is required.

Question 15Boiler Construction, Design, and Code Requirements

How must a safety valve be connected to a power boiler?

  1. Through a rupture disc mounted on the drum
  2. Through a shutoff valve so the valve can be serviced
  3. To the main steam header downstream of the stop valve
  4. Directly to the boiler with no intervening valve Correct answer.

Explanation

Safety valves must be attached directly to the boiler, as close as practicable, with no stop valve between the boiler and the valve. This prevents the boiler from being operated with its overpressure protection isolated.

Question 16Boiler Construction, Design, and Code Requirements

On a boiler equipped with a superheater, Section I requires:

  1. The superheater to be isolated by a valve during relief
  2. The superheater outlet valve to be set 10% above MAWP
  3. One or more safety valves at the superheater outlet Correct answer.
  4. No safety valve other than those on the boiler drum

Explanation

A safety valve must be installed at the superheater outlet so the superheater is protected when the main steam stop valve is closed. Its capacity is required in addition to the capacity of the drum safety valves.

Question 17Boiler Construction, Design, and Code Requirements

What is the minimum manhole opening size permitted by Section I?

  1. 8 in. by 12 in.
  2. 6 in. by 8 in.
  3. 10 in. by 16 in. Correct answer.
  4. 12 in. by 18 in.

Explanation

Section I requires openings large enough for internal cleaning and inspection, and sets the manhole minimum at 10 in. by 16 in. elliptical or 15 in. in diameter if circular. Larger openings are permitted.

Question 18Boiler Construction, Design, and Code Requirements

What is the smallest inlet size permitted for the safety relief valve on a Section IV heating boiler?

  1. 1/4 in. NPS
  2. 1 in. NPS
  3. 3/4 in. NPS Correct answer.
  4. 1/2 in. NPS

Explanation

Section IV requires each heating boiler to be equipped with a safety relief valve having an inlet of at least 3/4 in. NPS. A smaller valve would not provide dependable capacity for the boiler.

Question 19Boiler Construction, Design, and Code Requirements

With a power boiler at maximum firing and all safety valves open, the pressure may not rise above the maximum allowable working pressure by more than:

  1. 25 percent
  2. 10 percent Correct answer.
  3. 3 percent
  4. 5 percent

Explanation

Section I limits accumulation to 10 percent above the maximum allowable working pressure when the boiler is generating at its maximum rate with all safety valves discharging. The installed valve capacity must be sufficient to hold within that limit.

Question 20Boiler Construction, Design, and Code Requirements

Section IV requires an automatically fired steam heating boiler to be fitted with:

  1. A fusible plug in the crown sheet
  2. An automatic low-water fuel cutoff Correct answer.
  3. Two independent water columns
  4. A continuous blowdown system

Explanation

An automatic low-water fuel cutoff shuts off the burner before the water level falls out of the visible range of the gage glass. This protects the boiler from overheating and damage caused by low water.

Question 21Boiler Construction, Design, and Code Requirements

In the Section I shell thickness formula t = PD/(2SE + 2yP) + C, the coefficient y is used to:

  1. Provide the corrosion and erosion allowance
  2. Convert gauge pressure to absolute pressure
  3. Reflect the effect of metal temperature Correct answer.
  4. Allow for longitudinal weld joint efficiency

Explanation

The coefficient y varies with metal temperature and modifies the pressure term to reflect the changed stress distribution at elevated temperature, with y equal to 0.4 for ferritic steels at ordinary boiler temperatures. Weld joint efficiency appears separately as E, and the corrosion and erosion allowance is the term C.

Question 22Boiler Construction, Design, and Code Requirements

A cylindrical shell is drilled with tube holes in a regular pattern. Which ligament efficiency governs the thickness calculation?

  1. The lower of the two efficiencies Correct answer.
  2. The diagonal ligament efficiency only
  3. The longitudinal ligament efficiency only
  4. The average of the two efficiencies

Explanation

The shell is only as strong as its weakest path between adjacent holes, so the ligament efficiency used must be the lesser of the longitudinal and diagonal values. Using the higher value would overstate the strength of the drilled shell.

Question 23Boiler Construction, Design, and Code Requirements

Which of the following must be marked on the master nameplate of a Section I boiler?

  1. Date of the most recent hydrostatic test
  2. Fuel type and the burner manufacturer's name
  3. Maximum allowable working pressure Correct answer.
  4. Name of the insurance inspector

Explanation

The master nameplate identifies the boiler and its rating, including the manufacturer, the maximum allowable working pressure, the capacity, the heating surface, and the year built, along with the code symbol stamp. Test dates and inspector names are recorded on the manufacturer's data report.

Question 24Boiler Construction, Design, and Code Requirements

The maximum allowable working pressure of a boiler is determined by:

  1. The highest set pressure of its safety valves
  2. Half of the hydrostatic test pressure
  3. The weakest part at design temperature Correct answer.
  4. The normal operating pressure carried by the plant

Explanation

The maximum allowable working pressure is the highest pressure at which the weakest part of the boiler can be operated at the design metal temperature. It is established from the design calculations, and the safety valves are then set so they do not exceed it.

Question 25Boiler Construction, Design, and Code Requirements

A 4 in. diameter opening is cut in a boiler shell to receive a nozzle. Under Section I, the opening must be:

  1. Reinforced only if it exceeds 6 in. in diameter
  2. Compensated by increasing the safety valve capacity
  3. Accepted without reinforcement if fully radiographed
  4. Reinforced with metal equal in area to that removed Correct answer.

Explanation

An opening removes metal that was carrying the pressure load, so the area removed must be replaced by reinforcement in the shell or nozzle within the limits set by the code. Openings larger than the small-opening exemption always require this compensation.

Question 26Boiler Construction, Design, and Code Requirements

ASME Boiler and Pressure Vessel Code Section IV contains construction rules for:

  1. fiber-reinforced plastic pressure vessels
  2. heating boilers Correct answer.
  3. transport tanks
  4. power boilers

Explanation

Section IV applies to steam and hot-water heating boilers and their appurtenances. Power boilers are covered by Section I, while transport tanks and fiber-reinforced plastic vessels are addressed in other sections.

Question 27Boiler Construction, Design, and Code Requirements

In a hot-water heating system, the expansion tank is installed to:

  1. remove dissolved oxygen from the circulating water
  2. store a reserve supply of makeup water
  3. accept water volume changes caused by temperature swings Correct answer.
  4. raise the system pressure above the relief valve setpoint

Explanation

A closed hot-water system must have room for the water to expand and contract as its temperature changes. The expansion tank provides that volume without forcing the relief valve to open.

Question 28Boiler Construction, Design, and Code Requirements

A siphon is installed between a boiler and its steam pressure gage to:

  1. permit the gage to read vacuum as well as pressure
  2. keep live steam from directly entering the gage Correct answer.
  3. dampen pointer vibration during firing changes
  4. automatically reset the gage after an overpressure

Explanation

The siphon forms a loop that traps condensate, so high-temperature steam does not reach the gage mechanism. This protects the Bourdon tube and helps steady the reading.

Question 29Boiler Construction, Design, and Code Requirements

Under Section I, a new power boiler is normally hydrostatically tested at what pressure?

  1. 1.5 times the maximum allowable working pressure Correct answer.
  2. the maximum allowable working pressure
  3. 1.25 times the maximum allowable working pressure
  4. 2 times the maximum allowable working pressure

Explanation

Section I requires the hydrostatic test to be conducted at 1.5 times the maximum allowable working pressure. The test verifies tightness and strength of the completed boiler.

Question 30Boiler Construction, Design, and Code Requirements

Section I requires the safety valve on a steam boiler to be of which type?

  1. direct spring-loaded Correct answer.
  2. temperature-actuated
  3. pilot-operated with a rupture disk
  4. weighted-lever

Explanation

Section I steam-boiler safety valves must be direct spring-loaded and of the pop type. They must open and close reliably without depending on a pilot or external power source.

Question 31Boiler Construction, Design, and Code Requirements

Under Section IV, a cast iron steam heating boiler is limited to a maximum allowable working pressure of:

  1. 50 psig
  2. 30 psig
  3. 15 psig Correct answer.
  4. 100 psig

Explanation

Section IV limits cast iron steam heating boilers to 15 psig. Cast iron hot-water heating boilers are permitted a higher limit, but the steam limit remains 15 psig.

Question 32Boiler Construction, Design, and Code Requirements

Try cocks are provided on a boiler to:

  1. measure the boiler's steam output
  2. sample boiler water for chemical testing
  3. verify water level independently of the gage glass Correct answer.
  4. drain the boiler completely during a bottom blowdown

Explanation

Try cocks are small valves at different elevations on the water column or boiler head. Opening them gives a direct, independent check that water is at the expected level when the gage glass is suspect.

Question 33Boiler Construction, Design, and Code Requirements

ASME Boiler and Pressure Vessel Code Section VII provides recommended guidelines for:

  1. nondestructive examination
  2. construction of heating boilers
  3. care and operation of power boilers Correct answer.
  4. welding qualifications

Explanation

Section VII is the recommended guideline for the care and operation of power boilers. Construction rules are in Sections I and IV, while welding and NDE are handled in other sections.

Question 34Boiler Construction, Design, and Code Requirements

A handhole in a boiler is provided primarily to:

  1. serve as an emergency water feed connection during a pump failure
  2. mount the boiler's pressure gage
  3. allow a worker to enter the steam drum for repairs
  4. permit inspection and cleaning of internal surfaces Correct answer.

Explanation

A handhole is an access opening large enough for a hand and tools, not for a person to enter. It allows inspection, cleaning, and minor maintenance of internal surfaces and connections.

Question 35Boiler Construction, Design, and Code Requirements

A flat stayed plate is designed for 100 psi with stays on a 6 in. pitch. If the pitch is reduced to 3 in. while all other factors remain the same, the allowable pressure becomes approximately:

  1. 800 psi
  2. 200 psi
  3. 50 psi
  4. 400 psi Correct answer.

Explanation

For stayed flat surfaces, the allowable pressure varies inversely with the square of the stay pitch. Halving the pitch reduces the area supported by each stay to one-fourth, so the allowable pressure rises to about four times 100 psi.

Question 36Boiler Construction, Design, and Code Requirements

A cylindrical boiler shell has an inside diameter of 72 in. and a maximum allowable working pressure of 200 psi. Using t = PD/(2SE + 2yP) + C with S = 13,800 psi, E = 0.85, y = 0.40, and C = 0.125 in., the required thickness is closest to:

  1. 3/4 in. Correct answer.
  2. 7/8 in.
  3. 11/16 in.
  4. 5/8 in.

Explanation

Substituting gives 14,400 divided by 23,620, or about 0.610 in., plus 0.125 in. corrosion allowance, for about 0.735 in. The closest listed thickness is 3/4 in.

Question 37Boiler Fittings, Accessories, and Controls

What is the primary function of a safety valve on a steam boiler?

  1. Relieve pressure before it exceeds the maximum allowable working pressure Correct answer.
  2. Admit feedwater whenever the water level drops below the normal line
  3. Hold the steam header at a constant pressure as the load on the plant varies
  4. Drain condensate out of the steam header during start-up and warm-up

Explanation

The safety valve is the final overpressure protection for the boiler. It is set at or below the maximum allowable working pressure and must have enough relieving capacity to pass all the steam the boiler can generate. It plays no part in normal pressure regulation.

Question 38Boiler Fittings, Accessories, and Controls

Try cocks are used on a boiler to...

  1. Relieve pressure if the safety valve fails to open
  2. Measure the boiler steam pressure at the drum outlet
  3. Sample the boiler water so it can be chemically tested
  4. Verify the water level independently of the gauge glass Correct answer.

Explanation

Try cocks are small valves set at the top and bottom of the visible level range. Opening them shows whether steam or water is present at that point, giving a level check that does not depend on a clear glass.

Question 39Boiler Fittings, Accessories, and Controls

Why is a siphon (pigtail) installed between a steam boiler and its pressure gauge?

  1. It raises the maximum pressure the gauge can read
  2. It traps condensate so live steam cannot reach the gauge Correct answer.
  3. It lets the gauge be removed for calibration while steaming
  4. It keeps the gauge needle from showing a vacuum reading

Explanation

The loop fills with condensed steam, and that water leg keeps high-temperature steam away from the Bourdon tube and linkage. It also cushions the gauge from pressure pulsations in the steam space.

Question 40Boiler Fittings, Accessories, and Controls

When a low-water fuel cutoff trips on a steam boiler, the immediate result is that...

  1. the burner keeps firing while an alarm sounds
  2. the safety valve opens to vent the excess pressure
  3. the fuel supply to the burner is shut off Correct answer.
  4. the feedwater pump speeds up to restore the level

Explanation

The low-water fuel cutoff is a safety control that interrupts the fuel supply when the water level falls below the lowest safe level. This prevents overheating and damage to heating surfaces. Restoring the level is the job of the feed control, not the cutoff.

Question 41Boiler Fittings, Accessories, and Controls

Bottom blowdown on a steam boiler is performed mainly to...

  1. Wash scale off the outside surfaces of the boiler tubes
  2. Remove sludge and dissolved solids from the lowest part of the boiler Correct answer.
  3. Lower steam pressure quickly when the boiler is carrying too much load
  4. Cool the boiler water so the safety valve will reseat

Explanation

Bottom blowdown is a short opening of the blowoff valves that carries away sludge and the most concentrated dissolved solids from the bottom of the water space. It is normally done at light load with the water level near normal.

Question 42Boiler Fittings, Accessories, and Controls

What is the function of a steam trap in a steam distribution system?

  1. Reduce steam pressure before it reaches the heating equipment
  2. Remove water droplets from steam at the boiler outlet
  3. Discharge condensate and air while holding back steam Correct answer.
  4. Add heat to the steam just before it enters the coil

Explanation

A trap passes condensate and noncondensable gases while closing against live steam. This keeps heat-transfer equipment full of steam and free of water logging.

Question 43Boiler Fittings, Accessories, and Controls

A check valve installed in the feedwater line between the feed pump and the boiler serves to...

  1. Prevent boiler water from flowing back toward the pump Correct answer.
  2. Isolate the pump from the boiler for maintenance
  3. Regulate the rate of feedwater flow into the boiler
  4. Relieve excess pump pressure back to the feed tank

Explanation

The check valve closes when the pump stops or when boiler pressure exceeds pump discharge pressure. That keeps boiler water out of the feed line and protects the pump and its piping.

Question 44Boiler Fittings, Accessories, and Controls

A hot water heating boiler must be protected from overpressure by...

  1. A low-water fuel cutoff working alone
  2. A relief valve set at or below the allowable working pressure Correct answer.
  3. A safety valve set at the boiler's steam design pressure and stamped for steam service
  4. A fusible plug installed in the crown sheet of the furnace

Explanation

A hot water boiler is protected by a pressure relief valve whose setting does not exceed the boiler's maximum allowable working pressure. The valve must also be sized to pass the boiler's full capacity.

Question 45Boiler Fittings, Accessories, and Controls

The water column attached to a steam boiler is used to...

  1. Measure the density of the boiler water so it can be controlled
  2. Increase the amount of steam the boiler can store for peak loads
  3. Separate moisture from the steam before it leaves the boiler
  4. Provide a steady water level for the gauge glass and level controls Correct answer.

Explanation

The water column is a vertical chamber connected to the steam and water spaces. It dampens the violent level in the drum so the gauge glass and level controls see a steadier, more representative level.

Question 46Boiler Fittings, Accessories, and Controls

The purpose of a flame scanner in a burner management system is to...

  1. Measure the temperature of the flue gases leaving the boiler
  2. Light the pilot burner whenever the thermostat calls for heat from the boiler
  3. Prove a flame before fuel is admitted and while the burner fires Correct answer.
  4. Adjust the fuel-to-air ratio as the burner modulates

Explanation

The scanner must prove flame before fuel can be admitted and must keep proving it while the burner fires. If the signal is lost, the flame safeguard program closes the fuel valves within the allowed time.

Question 47Boiler Fittings, Accessories, and Controls

Which statement best distinguishes an operating control from a safety control on a boiler?

  1. Operating controls are mounted on the boiler shell, while safety controls are always mounted in the control panel
  2. Operating controls are electrical devices, while safety controls are purely mechanical devices
  3. Operating controls are tested once a year, while safety controls are never tested after installation
  4. Operating controls hold a set point by cycling the burner; safety controls act on unsafe conditions Correct answer.

Explanation

Operating controls are the normal regulating devices that cycle or modulate the burner to hold pressure, temperature or level. Safety controls such as low-water cutoffs and high limits act only when a limit is exceeded and are never used for routine regulation.

Question 48Boiler Fittings, Accessories, and Controls

On a hot water boiler, the high-limit temperature control differs from the operating aquastat in that the high limit...

  1. Controls the speed of the circulator pump
  2. Shuts the burner down if temperature exceeds a fixed upper setting Correct answer.
  3. Can be adjusted by the building occupants to suit their comfort
  4. Cycles the burner on and off to maintain the water temperature set point

Explanation

The high limit is set above the operating range and acts as a safety device if the operating control fails. It requires manual reset in most designs and is not used to hold the normal set point.

Question 49Boiler Fittings, Accessories, and Controls

A modulating burner control differs from an on-off control in that a modulating control...

  1. Positions the fuel valve and air damper to match the firing rate to the load Correct answer.
  2. Alternates between high fire and low fire at fixed time intervals
  3. Fires at full rate until the set point is reached, then shuts the burner down
  4. Holds the burner at low fire at all times to reduce cycling

Explanation

A modulating control moves the fuel valve and air damper together so firing rate follows the load. This keeps pressure or temperature nearly constant and reduces cycling losses.

Question 50Boiler Fittings, Accessories, and Controls

If a boiler's safety valve relieving capacity is less than the boiler's maximum generating capacity, the result can be that...

  1. The safety valve will chatter and lose its set pressure
  2. Boiler pressure can keep rising after the valve is fully open Correct answer.
  3. The safety valve will fail to reseat after it lifts
  4. The low-water cutoff will trip and stop the burner

Explanation

The valve must be able to pass at least as much steam as the boiler can produce. If it cannot, pressure continues to climb even with the valve wide open, which is an overpressure hazard.