Page 1 of 57
3rd Class Stationary Engineer License Exam
ACTUAL QUESTIONS AND ANSWERS LATEST
UPDATE THIS YEAR
3rd Class Stationary Engineer License Exam — Full Coverage
The 3rd Class Stationary Engineer License exam tests competency in the safe and efficient operation of
boilers, steam systems, and auxiliary equipment. Jurisdictions vary, but the exam universally covers
boiler design, combustion, water treatment, safety devices, thermodynamics, and applicable codes
(ASME, NBIC) . This question bank is based on NIULPE, ASOPE, municipal, and provincial exam standards,
with rationales provided for each answer.
Exam Coverage Summary
Domain Key Topics
Boiler Operation & Fire-tube vs. water-tube, HRT, Scotch marine, cast iron, package boilers; steam vs. hot wa
Design internal fittings (staybolts, tubesheets, baffles)
The 3 T's of combustion (Time, Temperature, Turbulence), gas train components, draft
Combustion & Fuels
(natural/forced/induced), burners, flame safeguards
Safety valves (ASME Section I), low-water cutoffs (LWCO), flame scanners, pressuretrols,
Safety Devices
fusible plugs, alarms
Water Treatment & Scale and corrosion prevention, blowdown (continuous & bottom), deaeration, chemical
Chemistry treatment (sodium sulfite, phosphates), condensate return
Gate, globe, check, blowdown valves; steam traps (float, thermodynamic, inverted bucket
Piping & Valves
pipe expansion, supports
Pressure gauges, gauge glasses, thermocouples, flow measurement (orifice plates), PLCs,
Instruments & Controls
interpretation
Thermodynamics & Heat Rankine cycle, saturated vs. superheated steam, sensible/latent heat,
Transfer conduction/convection/radiation, Ideal Gas Law, Boyle's/Charles' Laws
Maintenance & Boiler tube failure, priming and carryover, foaming, corrosion, cavitation, lockout/tagout
Troubleshooting (LOTO)
Codes & Safety ASME Section I (Power Boilers), ASME Section VIII (Pressure Vessels), NBIC, low-pressure v
Regulations high-pressure boilers, operator licensing requirements
, Page 2 of 57
1. What is the primary function of a boiler in a stationary power plant?
A) To generate electricity directly from fuel
B) To convert water into steam by applying heat energy
C) To cool circulating water for condensers
D) To compress air for pneumatic controls
Answer: B
Rationale: Boilers are heat exchangers designed to transfer energy from fuel combustion into water,
producing steam for heating, process, or power generation .
2. Which law relates the pressure, volume, and temperature of an ideal gas at a constant mass?
A) Newton's Law of Motion
B) Pascal's Law
C) The Ideal Gas Law (PV = nRT)
D) Hooke's Law
, Page 3 of 57
Answer: C
Rationale: The Ideal Gas Law (PV = nRT) is fundamental in steam systems for understanding how
pressure and temperature affect steam volume and density .
3. A fire-tube boiler is best suited for which application?
A) High-pressure steam for large electrical turbines
B) Low-pressure steam for heating and small-scale power
C) Supercritical steam generation
D) Nuclear reactor cooling
Answer: B
Rationale: Fire-tube boilers are typically used for low-pressure steam applications because the tubes are
inside a water-filled shell, limiting their pressure capability .
, Page 4 of 57
4. In a water-tube boiler, the water and steam are contained within the:
A) Outer shell
B) Tubes
C) Combustion chamber
D) Mud drum only
Answer: B
Rationale: Water-tube boilers circulate water inside the tubes while hot gases pass around them,
allowing for much higher pressures than fire-tube designs .
5. Which of the following equations correctly represents Boyle's Law for an ideal gas at constant
temperature?
A) P₁/T₁ = P₂/T₂
B) P₁V₁ = P₂V₂
C) V₁/T₁ = V₂/T₂
D) P₁V₁/T₁ = P₂V₂/T₂
3rd Class Stationary Engineer License Exam
ACTUAL QUESTIONS AND ANSWERS LATEST
UPDATE THIS YEAR
3rd Class Stationary Engineer License Exam — Full Coverage
The 3rd Class Stationary Engineer License exam tests competency in the safe and efficient operation of
boilers, steam systems, and auxiliary equipment. Jurisdictions vary, but the exam universally covers
boiler design, combustion, water treatment, safety devices, thermodynamics, and applicable codes
(ASME, NBIC) . This question bank is based on NIULPE, ASOPE, municipal, and provincial exam standards,
with rationales provided for each answer.
Exam Coverage Summary
Domain Key Topics
Boiler Operation & Fire-tube vs. water-tube, HRT, Scotch marine, cast iron, package boilers; steam vs. hot wa
Design internal fittings (staybolts, tubesheets, baffles)
The 3 T's of combustion (Time, Temperature, Turbulence), gas train components, draft
Combustion & Fuels
(natural/forced/induced), burners, flame safeguards
Safety valves (ASME Section I), low-water cutoffs (LWCO), flame scanners, pressuretrols,
Safety Devices
fusible plugs, alarms
Water Treatment & Scale and corrosion prevention, blowdown (continuous & bottom), deaeration, chemical
Chemistry treatment (sodium sulfite, phosphates), condensate return
Gate, globe, check, blowdown valves; steam traps (float, thermodynamic, inverted bucket
Piping & Valves
pipe expansion, supports
Pressure gauges, gauge glasses, thermocouples, flow measurement (orifice plates), PLCs,
Instruments & Controls
interpretation
Thermodynamics & Heat Rankine cycle, saturated vs. superheated steam, sensible/latent heat,
Transfer conduction/convection/radiation, Ideal Gas Law, Boyle's/Charles' Laws
Maintenance & Boiler tube failure, priming and carryover, foaming, corrosion, cavitation, lockout/tagout
Troubleshooting (LOTO)
Codes & Safety ASME Section I (Power Boilers), ASME Section VIII (Pressure Vessels), NBIC, low-pressure v
Regulations high-pressure boilers, operator licensing requirements
, Page 2 of 57
1. What is the primary function of a boiler in a stationary power plant?
A) To generate electricity directly from fuel
B) To convert water into steam by applying heat energy
C) To cool circulating water for condensers
D) To compress air for pneumatic controls
Answer: B
Rationale: Boilers are heat exchangers designed to transfer energy from fuel combustion into water,
producing steam for heating, process, or power generation .
2. Which law relates the pressure, volume, and temperature of an ideal gas at a constant mass?
A) Newton's Law of Motion
B) Pascal's Law
C) The Ideal Gas Law (PV = nRT)
D) Hooke's Law
, Page 3 of 57
Answer: C
Rationale: The Ideal Gas Law (PV = nRT) is fundamental in steam systems for understanding how
pressure and temperature affect steam volume and density .
3. A fire-tube boiler is best suited for which application?
A) High-pressure steam for large electrical turbines
B) Low-pressure steam for heating and small-scale power
C) Supercritical steam generation
D) Nuclear reactor cooling
Answer: B
Rationale: Fire-tube boilers are typically used for low-pressure steam applications because the tubes are
inside a water-filled shell, limiting their pressure capability .
, Page 4 of 57
4. In a water-tube boiler, the water and steam are contained within the:
A) Outer shell
B) Tubes
C) Combustion chamber
D) Mud drum only
Answer: B
Rationale: Water-tube boilers circulate water inside the tubes while hot gases pass around them,
allowing for much higher pressures than fire-tube designs .
5. Which of the following equations correctly represents Boyle's Law for an ideal gas at constant
temperature?
A) P₁/T₁ = P₂/T₂
B) P₁V₁ = P₂V₂
C) V₁/T₁ = V₂/T₂
D) P₁V₁/T₁ = P₂V₂/T₂
