KENTUCKY BOILER CONTRACTOR CERTIFICATION
EXAMINATION QUESTIONS AND ANSWERS
PRACTICE EXAMINATION QUESTIONS
Question 1
A facility's operating requirements demand both high-pressure steam for a turbine and low-
pressure steam for a heating process. Which boiler configuration is the most efficient and
appropriate for this specific application?
A. Fire-tube boiler with a superheater
B. Water-tube boiler with an economizer
C. A combined-cycle heat recovery steam generator (HRSG)
D. A boiler with a steam pressure-reducing station
Correct Answer: D
Explanation: A pressure-reducing station allows a single high-pressure boiler to supply
steam to both high and low-pressure systems by throttling and desuperheating the steam,
making it more efficient than running two separate boiler plants.
Question 2
During a routine inspection, you notice that the flame in a natural gas-fired boiler is lifting
off the burner tips. This condition is most likely caused by:
A. An insufficient primary air supply
B. An excessively high fuel gas pressure
C. An overly rich fuel-to-air mixture
D. A blocked burner orifice
Correct Answer: B
,Explanation: Flame lift-off occurs when the fuel gas velocity is too high for the flame to
stabilize on the burner. This is primarily due to excessive fuel gas pressure. A rich mixture
(C) would cause a lazy, yellow flame.
Question 3
A water sample taken from a fire-tube boiler shows a pH of 10.2 and a P-alkalinity of 600
ppm. Based on these readings, the boiler water is likely to be susceptible to which of the
following problems?
A. Acidic corrosion
B. Oxygen pitting
C. Caustic embrittlement/gauging
D. Silica scaling
Correct Answer: C
Explanation: A high pH (above 10.0) and high alkalinity create conditions for caustic
embrittlement, where caustic soda concentrates in boiler metal crevices, leading to stress
corrosion cracking. This is a classic symptom of over-alkaline conditions.
Question 4
A low-water fuel cut-off (LWCO) is a critical safety device. Which of the following
statements best describes its primary operating principle and required testing protocol?
A. It measures water temperature and must be tested weekly by manually lowering the
water level.
B. It senses water pressure and is tested monthly by simulating a low-pressure condition.
C. It monitors the water flow rate and should be tested annually by an independent
inspector.
D. It uses an electrode or float to detect water level and must be tested daily by briefly
blowing down the control.
Correct Answer: D
Explanation: LWCOs use a float or probe to physically sense the water level. The most
reliable test is the "evaporation test" or blow-down test, which simulates a low-water
condition to ensure the control shuts off the burner as required.
,Question 5
When installing a new steam boiler, the primary function of the Hartford Loop is to:
A. Increase the boiler's operating pressure
B. Provide a means for chemical feed to the boiler
C. Prevent the boiler from draining below a safe water level in the event of a return line leak
D. Allow for the expansion and contraction of the boiler shell
Correct Answer: C
Explanation: The Hartford Loop is a specific piping arrangement that prevents the boiler
from draining below the safe water line if a leak develops in the return piping system. It
ensures a constant water level is maintained.
Question 6
A facility operates a 500 HP water-tube boiler at 300 psig. Which of the following is the
primary code that governs the minimum required thickness of the boiler's shell and tubes?
A. ASME Section I (Power Boilers)
B. ASME Section VIII (Pressure Vessels)
C. National Fuel Gas Code (NFPA 54)
D. ASME B31.1 (Power Piping)
Correct Answer: A
Explanation: ASME Section I, "Rules for Construction of Power Boilers," sets the design,
fabrication, and inspection requirements, including minimum thickness calculations for all
power boiler components.
Question 7
An operator notices a sudden and significant drop in steam pressure while the burner is
firing at a high rate. Simultaneously, the stack temperature rises. This situation most likely
indicates:
A. A sudden increase in the feedwater temperature
B. A tube rupture or major steam leak in the system
C. An automatic blowdown system cycling on
D. The air preheater has become fouled
Correct Answer: B
, Explanation: A tube rupture creates a large, immediate demand for steam as water flashes
into steam, causing a pressure drop. The increased firing rate to compensate leads to
higher than normal stack temperatures due to poor heat transfer.
Question 8
What is the primary purpose of a non-return (stop-check) valve on a steam boiler outlet
header?
A. To regulate the flow of steam to the main header
B. To prevent the backflow of steam from the header into the boiler
C. To provide a means to relieve excess boiler pressure
D. To isolate the boiler from the main header for maintenance
Correct Answer: B
Explanation: The primary function of a non-return valve is to automatically close if the
header pressure becomes higher than the boiler pressure, preventing backflow. It differs
from a simple isolation valve (globe valve) which is used for manual isolation.
Question 9
A boiler is experiencing carryover, where water droplets are being carried with the steam.
Which of the following is the LEAST likely cause of this condition?
A. Operating at a high water level
B. A sudden and rapid increase in boiler load
C. High total dissolved solids (TDS) in the boiler water
D. Using feedwater that is too cold
Correct Answer: D
Explanation: Carryover is caused by mechanical issues (high water level, sudden load
changes) and chemical issues (high TDS, foam). Cold feedwater is not a direct cause of
carryover; it mainly affects thermal stress and efficiency.
Question 10
When conducting a hydrostatic test on a newly installed boiler, which of the following
pressures is required by code?
A. The maximum allowable working pressure (MAWP)
B. 1.5 times the MAWP
EXAMINATION QUESTIONS AND ANSWERS
PRACTICE EXAMINATION QUESTIONS
Question 1
A facility's operating requirements demand both high-pressure steam for a turbine and low-
pressure steam for a heating process. Which boiler configuration is the most efficient and
appropriate for this specific application?
A. Fire-tube boiler with a superheater
B. Water-tube boiler with an economizer
C. A combined-cycle heat recovery steam generator (HRSG)
D. A boiler with a steam pressure-reducing station
Correct Answer: D
Explanation: A pressure-reducing station allows a single high-pressure boiler to supply
steam to both high and low-pressure systems by throttling and desuperheating the steam,
making it more efficient than running two separate boiler plants.
Question 2
During a routine inspection, you notice that the flame in a natural gas-fired boiler is lifting
off the burner tips. This condition is most likely caused by:
A. An insufficient primary air supply
B. An excessively high fuel gas pressure
C. An overly rich fuel-to-air mixture
D. A blocked burner orifice
Correct Answer: B
,Explanation: Flame lift-off occurs when the fuel gas velocity is too high for the flame to
stabilize on the burner. This is primarily due to excessive fuel gas pressure. A rich mixture
(C) would cause a lazy, yellow flame.
Question 3
A water sample taken from a fire-tube boiler shows a pH of 10.2 and a P-alkalinity of 600
ppm. Based on these readings, the boiler water is likely to be susceptible to which of the
following problems?
A. Acidic corrosion
B. Oxygen pitting
C. Caustic embrittlement/gauging
D. Silica scaling
Correct Answer: C
Explanation: A high pH (above 10.0) and high alkalinity create conditions for caustic
embrittlement, where caustic soda concentrates in boiler metal crevices, leading to stress
corrosion cracking. This is a classic symptom of over-alkaline conditions.
Question 4
A low-water fuel cut-off (LWCO) is a critical safety device. Which of the following
statements best describes its primary operating principle and required testing protocol?
A. It measures water temperature and must be tested weekly by manually lowering the
water level.
B. It senses water pressure and is tested monthly by simulating a low-pressure condition.
C. It monitors the water flow rate and should be tested annually by an independent
inspector.
D. It uses an electrode or float to detect water level and must be tested daily by briefly
blowing down the control.
Correct Answer: D
Explanation: LWCOs use a float or probe to physically sense the water level. The most
reliable test is the "evaporation test" or blow-down test, which simulates a low-water
condition to ensure the control shuts off the burner as required.
,Question 5
When installing a new steam boiler, the primary function of the Hartford Loop is to:
A. Increase the boiler's operating pressure
B. Provide a means for chemical feed to the boiler
C. Prevent the boiler from draining below a safe water level in the event of a return line leak
D. Allow for the expansion and contraction of the boiler shell
Correct Answer: C
Explanation: The Hartford Loop is a specific piping arrangement that prevents the boiler
from draining below the safe water line if a leak develops in the return piping system. It
ensures a constant water level is maintained.
Question 6
A facility operates a 500 HP water-tube boiler at 300 psig. Which of the following is the
primary code that governs the minimum required thickness of the boiler's shell and tubes?
A. ASME Section I (Power Boilers)
B. ASME Section VIII (Pressure Vessels)
C. National Fuel Gas Code (NFPA 54)
D. ASME B31.1 (Power Piping)
Correct Answer: A
Explanation: ASME Section I, "Rules for Construction of Power Boilers," sets the design,
fabrication, and inspection requirements, including minimum thickness calculations for all
power boiler components.
Question 7
An operator notices a sudden and significant drop in steam pressure while the burner is
firing at a high rate. Simultaneously, the stack temperature rises. This situation most likely
indicates:
A. A sudden increase in the feedwater temperature
B. A tube rupture or major steam leak in the system
C. An automatic blowdown system cycling on
D. The air preheater has become fouled
Correct Answer: B
, Explanation: A tube rupture creates a large, immediate demand for steam as water flashes
into steam, causing a pressure drop. The increased firing rate to compensate leads to
higher than normal stack temperatures due to poor heat transfer.
Question 8
What is the primary purpose of a non-return (stop-check) valve on a steam boiler outlet
header?
A. To regulate the flow of steam to the main header
B. To prevent the backflow of steam from the header into the boiler
C. To provide a means to relieve excess boiler pressure
D. To isolate the boiler from the main header for maintenance
Correct Answer: B
Explanation: The primary function of a non-return valve is to automatically close if the
header pressure becomes higher than the boiler pressure, preventing backflow. It differs
from a simple isolation valve (globe valve) which is used for manual isolation.
Question 9
A boiler is experiencing carryover, where water droplets are being carried with the steam.
Which of the following is the LEAST likely cause of this condition?
A. Operating at a high water level
B. A sudden and rapid increase in boiler load
C. High total dissolved solids (TDS) in the boiler water
D. Using feedwater that is too cold
Correct Answer: D
Explanation: Carryover is caused by mechanical issues (high water level, sudden load
changes) and chemical issues (high TDS, foam). Cold feedwater is not a direct cause of
carryover; it mainly affects thermal stress and efficiency.
Question 10
When conducting a hydrostatic test on a newly installed boiler, which of the following
pressures is required by code?
A. The maximum allowable working pressure (MAWP)
B. 1.5 times the MAWP
