2nd Class Stationary Engineer License Exam
Questions And Correct Answers (Verified
Answers) Plus Rationales 2026 Q&A | Instant
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1. The primary purpose of a boiler’s safety valve is to:
A. Increase efficiency
B. Maintain water level
C. Prevent excessive pressure
D. Control fuel flow
Rationale: Safety valves are designed to release pressure when it
exceeds safe limits to prevent explosions.
2. Which of the following is the main cause of boiler scale
formation?
A. Low water level
B. Hard water minerals
C. High fuel efficiency
D. Excessive steam load
Rationale: Hard water contains calcium and magnesium, which
precipitate and form scale on boiler surfaces.
3. A boiler’s feedwater temperature affects:
A. Steam pressure only
B. Fuel efficiency
C. Chimney draft
D. Condensate flow
, Rationale: Preheating feedwater reduces fuel consumption
because less energy is needed to convert water into steam.
4. The function of a deaerator in a steam system is to:
A. Reduce fuel consumption
B. Remove dissolved gases from feedwater
C. Increase steam pressure
D. Cool exhaust steam
Rationale: Deaerators remove oxygen and carbon dioxide from
water, preventing corrosion in boilers and piping.
5. When performing a boiler blowdown, the main purpose is to:
A. Increase water temperature
B. Reduce steam pressure
C. Remove sludge and sediments
D. Test the water level gauge
Rationale: Blowdown removes accumulated solids to maintain
water quality and prevent damage to boiler tubes.
6. Which of the following is a sign of a leaking steam trap?
A. Boiler pressure drops
B. Water level rises
C. Continuous discharge of live steam
D. Fuel efficiency increases
Rationale: A properly functioning steam trap removes condensate
only; continuous steam discharge indicates failure.
7. The most common type of water tube boiler used in industry is:
A. Fire-tube boiler
B. D-type water tube boiler
C. Flash boiler
, D. Cast iron sectional boiler
Rationale: D-type water tube boilers are widely used for high-
pressure steam applications due to efficiency and safety.
8. Boiler feedwater should be chemically treated primarily to:
A. Reduce water temperature
B. Increase steam production
C. Prevent corrosion and scaling
D. Control pressure
Rationale: Chemical treatment protects metal surfaces and
extends boiler life by preventing scale and corrosion.
9. The purpose of a economizer in a boiler system is to:
A. Increase steam pressure
B. Reduce water impurities
C. Recover heat from flue gases
D. Remove condensate
Rationale: Economizers preheat feedwater using flue gas energy,
improving boiler efficiency.
10. Superheated steam differs from saturated steam because it:
A. Contains water droplets
B. Has temperature above the saturation point
C. Condenses easily
D. Has lower energy content
Rationale: Superheated steam is at a higher temperature than
saturated steam at the same pressure, which prevents
condensation in turbines.
11. The most important factor in preventing boiler corrosion is:
A. Fuel quality
Questions And Correct Answers (Verified
Answers) Plus Rationales 2026 Q&A | Instant
Download Pdf
1. The primary purpose of a boiler’s safety valve is to:
A. Increase efficiency
B. Maintain water level
C. Prevent excessive pressure
D. Control fuel flow
Rationale: Safety valves are designed to release pressure when it
exceeds safe limits to prevent explosions.
2. Which of the following is the main cause of boiler scale
formation?
A. Low water level
B. Hard water minerals
C. High fuel efficiency
D. Excessive steam load
Rationale: Hard water contains calcium and magnesium, which
precipitate and form scale on boiler surfaces.
3. A boiler’s feedwater temperature affects:
A. Steam pressure only
B. Fuel efficiency
C. Chimney draft
D. Condensate flow
, Rationale: Preheating feedwater reduces fuel consumption
because less energy is needed to convert water into steam.
4. The function of a deaerator in a steam system is to:
A. Reduce fuel consumption
B. Remove dissolved gases from feedwater
C. Increase steam pressure
D. Cool exhaust steam
Rationale: Deaerators remove oxygen and carbon dioxide from
water, preventing corrosion in boilers and piping.
5. When performing a boiler blowdown, the main purpose is to:
A. Increase water temperature
B. Reduce steam pressure
C. Remove sludge and sediments
D. Test the water level gauge
Rationale: Blowdown removes accumulated solids to maintain
water quality and prevent damage to boiler tubes.
6. Which of the following is a sign of a leaking steam trap?
A. Boiler pressure drops
B. Water level rises
C. Continuous discharge of live steam
D. Fuel efficiency increases
Rationale: A properly functioning steam trap removes condensate
only; continuous steam discharge indicates failure.
7. The most common type of water tube boiler used in industry is:
A. Fire-tube boiler
B. D-type water tube boiler
C. Flash boiler
, D. Cast iron sectional boiler
Rationale: D-type water tube boilers are widely used for high-
pressure steam applications due to efficiency and safety.
8. Boiler feedwater should be chemically treated primarily to:
A. Reduce water temperature
B. Increase steam production
C. Prevent corrosion and scaling
D. Control pressure
Rationale: Chemical treatment protects metal surfaces and
extends boiler life by preventing scale and corrosion.
9. The purpose of a economizer in a boiler system is to:
A. Increase steam pressure
B. Reduce water impurities
C. Recover heat from flue gases
D. Remove condensate
Rationale: Economizers preheat feedwater using flue gas energy,
improving boiler efficiency.
10. Superheated steam differs from saturated steam because it:
A. Contains water droplets
B. Has temperature above the saturation point
C. Condenses easily
D. Has lower energy content
Rationale: Superheated steam is at a higher temperature than
saturated steam at the same pressure, which prevents
condensation in turbines.
11. The most important factor in preventing boiler corrosion is:
A. Fuel quality
