STATIONARY ENGINEER EXAM STUDY GUIDE 2023
VERIFIED QUESTIONS & 100% CORRECT
ANSWERS | UPDATED STATIONARY ENGINEER
LICENSE EXAM PREP PDF
• Your all-in-one Stationary Engineer License Exam Prep — 200 verified multiple-
choice questions with correct answers and full EXPERT RATIONALE, designed to
simulate real exam conditions and reinforce key engineering concepts.
• Study tip: Work through each question independently before checking the
answer, then read the EXPERT RATIONALE carefully — this builds both recall and
deep understanding of why each answer is correct.
STATIONARY ENGINEER LICENSE EXAM
200 Verified Questions & 100% Correct Answers | 2026 Edition
1. What is the primary function of a boiler?
A. To generate electricity directly
B. To cool water for industrial use
C. To transfer heat to water to produce steam or hot water
D. To compress air for pneumatic systems
E. To store pressurized gas
Correct Answer: C. To transfer heat to water to produce steam or hot
water
EXPERT RATIONALE: A boiler is a closed vessel in which water is heated using a
heat source (fuel combustion, electricity, etc.) to produce steam or hot water for
heating, power generation, or industrial processes.
2. What does MAWP stand for in boiler terminology?
A. Maximum Actual Working Pressure
, B. Minimum Allowable Working Pressure
C. Maximum Allowable Working Pressure
D. Measured Average Water Pressure
E. Minimum Average Water Pressure
Correct Answer: C. Maximum Allowable Working Pressure
EXPERT RATIONALE: MAWP is the maximum pressure at which a boiler or
pressure vessel is designed to operate safely. It is stamped on the vessel and must
not be exceeded during operation.
3. Which type of boiler has water inside the tubes and hot gases on the
outside?
A. Fire-tube boiler
B. Cast iron boiler
C. Electric boiler
D. Water-tube boiler
E. Coil boiler
Correct Answer: D. Water-tube boiler
EXPERT RATIONALE: In a water-tube boiler, water flows inside the tubes while
hot combustion gases surround the outside of the tubes, allowing for higher
pressures and faster steam generation compared to fire-tube designs.
4. In a fire-tube boiler, where do the hot gases travel?
A. Through tubes surrounded by water
B. Through an external heat exchanger
C. Through the steam drum
, D. Through a condenser coil
E. Through the feedwater heater
Correct Answer: A. Through tubes surrounded by water
EXPERT RATIONALE: In a fire-tube boiler, hot combustion gases pass through
tubes that are submerged in water. The heat transfers from the gases through the
tube walls to the surrounding water, producing steam.
5. What is the purpose of a safety valve on a boiler?
A. To maintain water level
B. To regulate fuel flow
C. To relieve excess pressure and prevent explosion
D. To control steam temperature
E. To drain the boiler
Correct Answer: C. To relieve excess pressure and prevent explosion
EXPERT RATIONALE: Safety valves are spring-loaded devices that automatically
open when pressure exceeds the set point, releasing steam to prevent dangerous
overpressure that could cause a catastrophic boiler explosion.
6. How often should a boiler safety valve be manually tested?
A. Once every five years
B. Only when the boiler is replaced
C. At least once per operating season or as required by code
D. Every ten years
E. Never — it is self-testing
, Correct Answer: C. At least once per operating season or as required by
code
EXPERT RATIONALE: Safety valves must be periodically tested to ensure they
open at the correct set pressure. Failure to test can result in a stuck valve that won't
open during an overpressure event, posing a serious safety hazard.
7. What is the function of a low-water cutoff on a boiler?
A. To reduce steam pressure automatically
B. To shut off the burner when water drops below a safe level
C. To drain excess water from the system
D. To control feedwater temperature
E. To regulate steam flow to the turbine
Correct Answer: B. To shut off the burner when water drops below a safe
level
EXPERT RATIONALE: A low-water cutoff is a critical safety device that
automatically shuts off the burner if water drops below the minimum safe
operating level, preventing overheating and potential boiler failure or explosion.
8. What causes a boiler to "prime"?
A. Insufficient fuel supply
B. Excess air in the combustion chamber
C. Carryover of water droplets into the steam supply
D. Low fire operation
E. Blocked flue gas passages
Correct Answer: C. Carryover of water droplets into the steam supply
VERIFIED QUESTIONS & 100% CORRECT
ANSWERS | UPDATED STATIONARY ENGINEER
LICENSE EXAM PREP PDF
• Your all-in-one Stationary Engineer License Exam Prep — 200 verified multiple-
choice questions with correct answers and full EXPERT RATIONALE, designed to
simulate real exam conditions and reinforce key engineering concepts.
• Study tip: Work through each question independently before checking the
answer, then read the EXPERT RATIONALE carefully — this builds both recall and
deep understanding of why each answer is correct.
STATIONARY ENGINEER LICENSE EXAM
200 Verified Questions & 100% Correct Answers | 2026 Edition
1. What is the primary function of a boiler?
A. To generate electricity directly
B. To cool water for industrial use
C. To transfer heat to water to produce steam or hot water
D. To compress air for pneumatic systems
E. To store pressurized gas
Correct Answer: C. To transfer heat to water to produce steam or hot
water
EXPERT RATIONALE: A boiler is a closed vessel in which water is heated using a
heat source (fuel combustion, electricity, etc.) to produce steam or hot water for
heating, power generation, or industrial processes.
2. What does MAWP stand for in boiler terminology?
A. Maximum Actual Working Pressure
, B. Minimum Allowable Working Pressure
C. Maximum Allowable Working Pressure
D. Measured Average Water Pressure
E. Minimum Average Water Pressure
Correct Answer: C. Maximum Allowable Working Pressure
EXPERT RATIONALE: MAWP is the maximum pressure at which a boiler or
pressure vessel is designed to operate safely. It is stamped on the vessel and must
not be exceeded during operation.
3. Which type of boiler has water inside the tubes and hot gases on the
outside?
A. Fire-tube boiler
B. Cast iron boiler
C. Electric boiler
D. Water-tube boiler
E. Coil boiler
Correct Answer: D. Water-tube boiler
EXPERT RATIONALE: In a water-tube boiler, water flows inside the tubes while
hot combustion gases surround the outside of the tubes, allowing for higher
pressures and faster steam generation compared to fire-tube designs.
4. In a fire-tube boiler, where do the hot gases travel?
A. Through tubes surrounded by water
B. Through an external heat exchanger
C. Through the steam drum
, D. Through a condenser coil
E. Through the feedwater heater
Correct Answer: A. Through tubes surrounded by water
EXPERT RATIONALE: In a fire-tube boiler, hot combustion gases pass through
tubes that are submerged in water. The heat transfers from the gases through the
tube walls to the surrounding water, producing steam.
5. What is the purpose of a safety valve on a boiler?
A. To maintain water level
B. To regulate fuel flow
C. To relieve excess pressure and prevent explosion
D. To control steam temperature
E. To drain the boiler
Correct Answer: C. To relieve excess pressure and prevent explosion
EXPERT RATIONALE: Safety valves are spring-loaded devices that automatically
open when pressure exceeds the set point, releasing steam to prevent dangerous
overpressure that could cause a catastrophic boiler explosion.
6. How often should a boiler safety valve be manually tested?
A. Once every five years
B. Only when the boiler is replaced
C. At least once per operating season or as required by code
D. Every ten years
E. Never — it is self-testing
, Correct Answer: C. At least once per operating season or as required by
code
EXPERT RATIONALE: Safety valves must be periodically tested to ensure they
open at the correct set pressure. Failure to test can result in a stuck valve that won't
open during an overpressure event, posing a serious safety hazard.
7. What is the function of a low-water cutoff on a boiler?
A. To reduce steam pressure automatically
B. To shut off the burner when water drops below a safe level
C. To drain excess water from the system
D. To control feedwater temperature
E. To regulate steam flow to the turbine
Correct Answer: B. To shut off the burner when water drops below a safe
level
EXPERT RATIONALE: A low-water cutoff is a critical safety device that
automatically shuts off the burner if water drops below the minimum safe
operating level, preventing overheating and potential boiler failure or explosion.
8. What causes a boiler to "prime"?
A. Insufficient fuel supply
B. Excess air in the combustion chamber
C. Carryover of water droplets into the steam supply
D. Low fire operation
E. Blocked flue gas passages
Correct Answer: C. Carryover of water droplets into the steam supply
