Stationary Engineer Second Class Exam
Practice Questions And Correct Answers
(Verified Answers) Plus Rationale 2026
Q&A| Instant Download Pdf
1.A second-class stationary engineer is operating a high-pressure steam
boiler. Which device is primarily responsible for preventing excessive
pressure buildup by automatically releasing steam when the boiler pressure
exceeds the set limit?
A. Pressure gauge
B. Safety valve
C. Blowdown valve
D. Feedwater regulator
Correct Answer: B. Safety valve
The safety valve is a critical boiler protection device designed to
automatically open when steam pressure exceeds the approved operating
limit, preventing dangerous overpressure conditions and possible boiler
failure.
2. Before placing a boiler into service after a shutdown, which procedure
should be performed first to ensure safe operation?
A. Increase the firing rate immediately
B. Close all water connections
C. Inspect the boiler, controls, and safety devices
D. Disable automatic controls
,Correct Answer: C. Inspect the boiler, controls, and safety devices
A complete inspection of the boiler, safety devices, controls, and operating
conditions must be completed before startup to identify hazards and
confirm that the equipment is ready for operation.
3. The primary function of a boiler feedwater pump is to:
A. Remove dissolved gases from water
B. Supply water to the boiler at sufficient pressure
C. Increase steam temperature
D. Reduce boiler pressure
Correct Answer: B. Supply water to the boiler at sufficient pressure
A feedwater pump delivers treated water into the boiler against the
internal steam pressure, maintaining the proper water level required for
safe steam generation.
4. What is the main purpose of boiler blowdown?
A. Increase combustion efficiency
B. Remove concentrated impurities from boiler water
C. Increase steam pressure
D. Cool the furnace area
Correct Answer: B. Remove concentrated impurities from boiler water
Blowdown removes dissolved solids, sludge, and impurities that
accumulate in boiler water, helping prevent scale formation, corrosion,
and poor steam quality.
5. A boiler water level that becomes too low is dangerous because it can:
A. Reduce fuel consumption
B. Cause overheating of boiler heating surfaces
,C. Increase water treatment efficiency
D. Improve steam quality
Correct Answer: B. Cause overheating of boiler heating surfaces
Low water conditions expose heating surfaces to direct flame or hot gases,
which can cause severe overheating, structural damage, and possible
boiler failure.
6. The instrument used to measure steam pressure inside a boiler is
called a:
A. Thermometer
B. Pressure gauge
C. Hydrometer
D. Flow meter
Correct Answer: B. Pressure gauge
A pressure gauge provides a continuous indication of the boiler’s internal
steam pressure, allowing the operator to maintain safe operating
conditions.
7. The main purpose of a boiler water treatment program is to:
A. Increase fuel consumption
B. Prevent scale and corrosion
C. Reduce steam production
D. Eliminate the need for inspections
Correct Answer: B. Prevent scale and corrosion
Proper water treatment controls impurities and chemical conditions in
boiler water, reducing deposits, corrosion, and operational problems.
8. In a steam boiler, the combustion process takes place in the:
, A. Steam drum
B. Furnace
C. Economizer
D. Superheater
Correct Answer: B. Furnace
The furnace is the area where fuel is burned and heat is released, providing
the energy required to convert water into steam.
9. The purpose of a boiler economizer is to:
A. Heat feedwater using waste heat from flue gases
B. Increase fuel pressure
C. Reduce steam temperature
D. Remove ash from fuel
Correct Answer: A. Heat feedwater using waste heat from flue gases
An economizer improves boiler efficiency by recovering heat from exhaust
gases and transferring it to incoming feedwater.
10. A superheater in a steam boiler is used to:
A. Convert water into steam
B. Increase steam temperature above saturation temperature
C. Remove dissolved solids
D. Reduce combustion air
Correct Answer: B. Increase steam temperature above saturation
temperature
A superheater raises steam temperature beyond its boiling point,
producing dry, high-temperature steam that improves efficiency in steam
equipment.
11. The main purpose of a steam trap is to:
Practice Questions And Correct Answers
(Verified Answers) Plus Rationale 2026
Q&A| Instant Download Pdf
1.A second-class stationary engineer is operating a high-pressure steam
boiler. Which device is primarily responsible for preventing excessive
pressure buildup by automatically releasing steam when the boiler pressure
exceeds the set limit?
A. Pressure gauge
B. Safety valve
C. Blowdown valve
D. Feedwater regulator
Correct Answer: B. Safety valve
The safety valve is a critical boiler protection device designed to
automatically open when steam pressure exceeds the approved operating
limit, preventing dangerous overpressure conditions and possible boiler
failure.
2. Before placing a boiler into service after a shutdown, which procedure
should be performed first to ensure safe operation?
A. Increase the firing rate immediately
B. Close all water connections
C. Inspect the boiler, controls, and safety devices
D. Disable automatic controls
,Correct Answer: C. Inspect the boiler, controls, and safety devices
A complete inspection of the boiler, safety devices, controls, and operating
conditions must be completed before startup to identify hazards and
confirm that the equipment is ready for operation.
3. The primary function of a boiler feedwater pump is to:
A. Remove dissolved gases from water
B. Supply water to the boiler at sufficient pressure
C. Increase steam temperature
D. Reduce boiler pressure
Correct Answer: B. Supply water to the boiler at sufficient pressure
A feedwater pump delivers treated water into the boiler against the
internal steam pressure, maintaining the proper water level required for
safe steam generation.
4. What is the main purpose of boiler blowdown?
A. Increase combustion efficiency
B. Remove concentrated impurities from boiler water
C. Increase steam pressure
D. Cool the furnace area
Correct Answer: B. Remove concentrated impurities from boiler water
Blowdown removes dissolved solids, sludge, and impurities that
accumulate in boiler water, helping prevent scale formation, corrosion,
and poor steam quality.
5. A boiler water level that becomes too low is dangerous because it can:
A. Reduce fuel consumption
B. Cause overheating of boiler heating surfaces
,C. Increase water treatment efficiency
D. Improve steam quality
Correct Answer: B. Cause overheating of boiler heating surfaces
Low water conditions expose heating surfaces to direct flame or hot gases,
which can cause severe overheating, structural damage, and possible
boiler failure.
6. The instrument used to measure steam pressure inside a boiler is
called a:
A. Thermometer
B. Pressure gauge
C. Hydrometer
D. Flow meter
Correct Answer: B. Pressure gauge
A pressure gauge provides a continuous indication of the boiler’s internal
steam pressure, allowing the operator to maintain safe operating
conditions.
7. The main purpose of a boiler water treatment program is to:
A. Increase fuel consumption
B. Prevent scale and corrosion
C. Reduce steam production
D. Eliminate the need for inspections
Correct Answer: B. Prevent scale and corrosion
Proper water treatment controls impurities and chemical conditions in
boiler water, reducing deposits, corrosion, and operational problems.
8. In a steam boiler, the combustion process takes place in the:
, A. Steam drum
B. Furnace
C. Economizer
D. Superheater
Correct Answer: B. Furnace
The furnace is the area where fuel is burned and heat is released, providing
the energy required to convert water into steam.
9. The purpose of a boiler economizer is to:
A. Heat feedwater using waste heat from flue gases
B. Increase fuel pressure
C. Reduce steam temperature
D. Remove ash from fuel
Correct Answer: A. Heat feedwater using waste heat from flue gases
An economizer improves boiler efficiency by recovering heat from exhaust
gases and transferring it to incoming feedwater.
10. A superheater in a steam boiler is used to:
A. Convert water into steam
B. Increase steam temperature above saturation temperature
C. Remove dissolved solids
D. Reduce combustion air
Correct Answer: B. Increase steam temperature above saturation
temperature
A superheater raises steam temperature beyond its boiling point,
producing dry, high-temperature steam that improves efficiency in steam
equipment.
11. The main purpose of a steam trap is to:
