Grade 1–5 Stationary Engineer License
Exam Prep
200 Questions & Answers with Rationales |
2026–2027 Edition
SECTION 1: BOILER OPERATION & FUNDAMENTALS (Questions 1–35)
Q1: A boiler horsepower is defined as the evaporation of:
A) 34.5 pounds of water per hour at 212°F
B) 45.3 pounds of water per hour at 212°F
C) 34.5 pounds of water per hour at 100°F
D) 50 pounds of water per hour at 212°F
Answer: A
Rationale: One boiler horsepower (BHP) is the equivalent evaporation of 34.5
pounds of water per hour from and at 212°F. This is the standard unit used to rate
boiler capacity .
Q2: A low-pressure steam boiler has a maximum allowable working pressure
(MAWP) of up to:
A) 15 psi
B) 30 psi
C) 100 psi
D) 250 psi
Answer: A
,Rationale: ASME Section IV defines low-pressure heating boilers as those
operating at ≤15 psi for steam or ≤160 psi for hot water. High-pressure boilers
operate above 15 psi .
Q3: The most important fitting on a boiler is the:
A) Pressure gauge
B) Water column
C) Safety valve
D) Blowdown valve
Answer: C
Rationale: The safety valve is the most critical safety device on a boiler. It
prevents the boiler from exceeding its MAWP by automatically releasing steam
when pressure becomes too high .
Q4: According to ASME code, boilers operating at 100 psi or over must have:
A) One bottom blowdown valve
B) Two bottom blowdown valves
C) Three bottom blowdown valves
D) No bottom blowdown valves required
Answer: B
Rationale: ASME code requires that boilers operating at 100 psi or higher must be
equipped with two bottom blowdown valves for safety redundancy .
Q5: Scale formation on boiler tubes is a direct cause of:
A) Improved heat transfer
B) Overheating of the tubes
C) Increased boiler efficiency
D) Reduced fuel consumption
Answer: B
,Rationale: Scale deposits act as an insulator, preventing proper heat transfer from
the tube surface to the water. This causes the tube metal to overheat, potentially
leading to tube failure .
Q6: Carbon dioxide (CO₂) in the flue gas indicates:
A) Incomplete combustion
B) Complete combustion
C) Excess air only
D) Fuel-rich conditions
Answer: B
Rationale: The presence of CO₂ in flue gas indicates complete combustion of
carbon in the fuel. Carbon monoxide (CO) would indicate incomplete combustion .
Q7: Carbon monoxide (CO) in the flue gas indicates:
A) Complete combustion
B) Incomplete combustion
C) Proper air-to-fuel ratio
D) Maximum boiler efficiency
Answer: B
Rationale: CO in flue gas is a sign of incomplete combustion, indicating
insufficient oxygen for complete oxidation of the fuel. This represents wasted fuel
and potential safety hazards .
Q8: Gauge pressure plus atmospheric pressure equals:
A) Vacuum pressure
B) Absolute pressure
C) Differential pressure
D) Static pressure
Answer: B
, Rationale: Absolute pressure = Gauge pressure + Atmospheric pressure (14.7 psi at
k. k. k. k. k. k. k. k. k. k. k.
sea level). This relationship is fundamental to understanding boiler pressure
k. k. k. k. k. k. k. k. k. k.
measurements .
k. k.
Q9: The main purpose of a water column is to:
k. k. k. k. k. k. k. k. k.
A) Increase boiler pressure k. k.
B) Reduce turbulence in the gauge glass for an accurate water level reading
k. k. k. k. k. k. k. k. k. k. k.
C) Heat feedwater k.
D) Remove impurities from steam k. k. k.
Answer: B k.
Rationale: A water column reduces water turbulence and provides a stable water
k. k. k. k. k. k. k. k. k. k. k.
level reading in the gauge glass, ensuring accurate monitoring of the boiler water
k. k. k. k. k. k. k. k. k. k. k. k. k.
level .
k. k.
Q10: A safety valve will:
k. k. k. k.
A) Increase boiler pressure k. k.
B) Prevent the boiler from exceeding its MAWP
k. k. k. k. k. k.
C) Regulate fuel flow k. k.
D) Control water level k. k.
Answer: B k.
Rationale: The safety valve is designed to automatically open when boiler
k. k. k. k. k. k. k. k. k. k.
pressure reaches the set point, releasing steam to prevent pressure from exceeding
k. k. k. k. k. k. k. k. k. k. k. k.
the MAWP .
k. k. k.
Q11: Which boiler type has the largest volume of water in relation to horsepower
k. k. k. k. k. k. k. k. k. k. k. k. k.
size?
k.
A) Watertube boiler k.
B) Firetube boiler k.
Exam Prep
200 Questions & Answers with Rationales |
2026–2027 Edition
SECTION 1: BOILER OPERATION & FUNDAMENTALS (Questions 1–35)
Q1: A boiler horsepower is defined as the evaporation of:
A) 34.5 pounds of water per hour at 212°F
B) 45.3 pounds of water per hour at 212°F
C) 34.5 pounds of water per hour at 100°F
D) 50 pounds of water per hour at 212°F
Answer: A
Rationale: One boiler horsepower (BHP) is the equivalent evaporation of 34.5
pounds of water per hour from and at 212°F. This is the standard unit used to rate
boiler capacity .
Q2: A low-pressure steam boiler has a maximum allowable working pressure
(MAWP) of up to:
A) 15 psi
B) 30 psi
C) 100 psi
D) 250 psi
Answer: A
,Rationale: ASME Section IV defines low-pressure heating boilers as those
operating at ≤15 psi for steam or ≤160 psi for hot water. High-pressure boilers
operate above 15 psi .
Q3: The most important fitting on a boiler is the:
A) Pressure gauge
B) Water column
C) Safety valve
D) Blowdown valve
Answer: C
Rationale: The safety valve is the most critical safety device on a boiler. It
prevents the boiler from exceeding its MAWP by automatically releasing steam
when pressure becomes too high .
Q4: According to ASME code, boilers operating at 100 psi or over must have:
A) One bottom blowdown valve
B) Two bottom blowdown valves
C) Three bottom blowdown valves
D) No bottom blowdown valves required
Answer: B
Rationale: ASME code requires that boilers operating at 100 psi or higher must be
equipped with two bottom blowdown valves for safety redundancy .
Q5: Scale formation on boiler tubes is a direct cause of:
A) Improved heat transfer
B) Overheating of the tubes
C) Increased boiler efficiency
D) Reduced fuel consumption
Answer: B
,Rationale: Scale deposits act as an insulator, preventing proper heat transfer from
the tube surface to the water. This causes the tube metal to overheat, potentially
leading to tube failure .
Q6: Carbon dioxide (CO₂) in the flue gas indicates:
A) Incomplete combustion
B) Complete combustion
C) Excess air only
D) Fuel-rich conditions
Answer: B
Rationale: The presence of CO₂ in flue gas indicates complete combustion of
carbon in the fuel. Carbon monoxide (CO) would indicate incomplete combustion .
Q7: Carbon monoxide (CO) in the flue gas indicates:
A) Complete combustion
B) Incomplete combustion
C) Proper air-to-fuel ratio
D) Maximum boiler efficiency
Answer: B
Rationale: CO in flue gas is a sign of incomplete combustion, indicating
insufficient oxygen for complete oxidation of the fuel. This represents wasted fuel
and potential safety hazards .
Q8: Gauge pressure plus atmospheric pressure equals:
A) Vacuum pressure
B) Absolute pressure
C) Differential pressure
D) Static pressure
Answer: B
, Rationale: Absolute pressure = Gauge pressure + Atmospheric pressure (14.7 psi at
k. k. k. k. k. k. k. k. k. k. k.
sea level). This relationship is fundamental to understanding boiler pressure
k. k. k. k. k. k. k. k. k. k.
measurements .
k. k.
Q9: The main purpose of a water column is to:
k. k. k. k. k. k. k. k. k.
A) Increase boiler pressure k. k.
B) Reduce turbulence in the gauge glass for an accurate water level reading
k. k. k. k. k. k. k. k. k. k. k.
C) Heat feedwater k.
D) Remove impurities from steam k. k. k.
Answer: B k.
Rationale: A water column reduces water turbulence and provides a stable water
k. k. k. k. k. k. k. k. k. k. k.
level reading in the gauge glass, ensuring accurate monitoring of the boiler water
k. k. k. k. k. k. k. k. k. k. k. k. k.
level .
k. k.
Q10: A safety valve will:
k. k. k. k.
A) Increase boiler pressure k. k.
B) Prevent the boiler from exceeding its MAWP
k. k. k. k. k. k.
C) Regulate fuel flow k. k.
D) Control water level k. k.
Answer: B k.
Rationale: The safety valve is designed to automatically open when boiler
k. k. k. k. k. k. k. k. k. k.
pressure reaches the set point, releasing steam to prevent pressure from exceeding
k. k. k. k. k. k. k. k. k. k. k. k.
the MAWP .
k. k. k.
Q11: Which boiler type has the largest volume of water in relation to horsepower
k. k. k. k. k. k. k. k. k. k. k. k. k.
size?
k.
A) Watertube boiler k.
B) Firetube boiler k.
