Newest 3rd Class Stationary Steam Engineer License Practice
2026/2027 Exam, with answers and rationales/instant pdf
1. What is the primary purpose of a boiler?
A. Produce steam by transferring heat to water
B. Store compressed air
C. Cool feedwater
D. Remove dissolved oxygen only
Answer: A
Rationale: A boiler transfers heat to water to produce steam.
2. What is the purpose of a safety valve on a boiler?
A. Prevent excessive pressure
B. Increase steam pressure
C. Control feedwater temperature
D. Remove scale
Answer: A
Rationale: A safety valve automatically releases steam when pressure reaches its set point.
3. Boiler pressure is commonly measured in:
A. PSI
B. Gallons
C. Feet per second
D. Degrees Celsius only
Answer: A
Rationale: Pounds per square inch (psi) is a common unit for pressure.
4. What does a boiler water-level gauge indicate?
A. Water level inside the boiler
B. Steam temperature only
C. Fuel pressure
D. Stack temperature
Answer: A
Rationale: The gauge glass provides a visual indication of boiler water level.
5. A low-water condition in a fired boiler is dangerous because it can:
A. Expose heated surfaces and cause overheating
B. Increase water circulation
C. Improve heat transfer
D. Reduce the possibility of tube damage
,Answer: A
Rationale: Insufficient water can expose heating surfaces, causing severe overheating and
potentially catastrophic failure.
6. What should an operator do if the boiler water level becomes dangerously low?
A. Follow emergency shutdown procedures and applicable operating instructions
B. Immediately add large amounts of cold water to a severely overheated boiler
C. Increase firing rate
D. Disable the low-water cutoff
Answer: A
Rationale: A severe low-water condition requires immediate action according to the boiler's
approved emergency procedures. Rapid introduction of water into an overheated boiler can be
extremely dangerous.
7. What is the function of a low-water cutoff?
A. Shut down the burner when water level becomes unsafe
B. Increase steam pressure
C. Add chemicals automatically in every system
D. Control building temperature
Answer: A
Rationale: The low-water cutoff protects the boiler from firing without sufficient water.
8. What is the purpose of a pressure gauge?
A. Indicate steam or boiler pressure
B. Measure water volume
C. Measure fuel consumption
D. Detect scale thickness
Answer: A
Rationale: Pressure gauges allow the operator to monitor system pressure.
9. What does boiler blowdown accomplish?
A. Removes concentrated dissolved solids and sludge
B. Increases dissolved solids
C. Adds oxygen to feedwater
D. Raises boiler water level permanently
Answer: A
Rationale: Blowdown removes water containing concentrated impurities and suspended solids.
10. Excessive dissolved solids in boiler water can contribute to:
A. Foaming and carryover
B. Better steam purity
, C. Lower corrosion risk in every case
D. Improved heat transfer
Answer: A
Rationale: High dissolved-solids concentrations can promote foaming and steam carryover.
11. What is steam carryover?
A. Water or boiler-water impurities leaving with the steam
B. Steam returning to the boiler
C. Fuel entering the feedwater
D. Condensate entering the stack
Answer: A
Rationale: Carryover occurs when moisture and/or dissolved or suspended boiler-water material
is transported with steam.
12. What is the purpose of a steam trap?
A. Remove condensate while retaining steam
B. Increase boiler pressure
C. Remove all dissolved oxygen
D. Add water to the boiler
Answer: A
Rationale: Steam traps discharge condensate and non-condensable gases while minimizing live-
steam loss.
13. Condensate is:
A. Water formed when steam loses heat and condenses
B. Fuel oil
C. Boiler scale
D. Compressed air
Answer: A
Rationale: Steam changes back into liquid water when heat is removed.
14. What is the purpose of a feedwater pump?
A. Deliver water to the boiler at sufficient pressure
B. Remove steam from the boiler
C. Reduce combustion air
D. Increase stack draft
Answer: A
Rationale: Feedwater pumps provide the pressure needed to force feedwater into the boiler.
15. Why must feedwater pressure exceed boiler pressure?
A. To allow water to enter the pressurized boiler
2026/2027 Exam, with answers and rationales/instant pdf
1. What is the primary purpose of a boiler?
A. Produce steam by transferring heat to water
B. Store compressed air
C. Cool feedwater
D. Remove dissolved oxygen only
Answer: A
Rationale: A boiler transfers heat to water to produce steam.
2. What is the purpose of a safety valve on a boiler?
A. Prevent excessive pressure
B. Increase steam pressure
C. Control feedwater temperature
D. Remove scale
Answer: A
Rationale: A safety valve automatically releases steam when pressure reaches its set point.
3. Boiler pressure is commonly measured in:
A. PSI
B. Gallons
C. Feet per second
D. Degrees Celsius only
Answer: A
Rationale: Pounds per square inch (psi) is a common unit for pressure.
4. What does a boiler water-level gauge indicate?
A. Water level inside the boiler
B. Steam temperature only
C. Fuel pressure
D. Stack temperature
Answer: A
Rationale: The gauge glass provides a visual indication of boiler water level.
5. A low-water condition in a fired boiler is dangerous because it can:
A. Expose heated surfaces and cause overheating
B. Increase water circulation
C. Improve heat transfer
D. Reduce the possibility of tube damage
,Answer: A
Rationale: Insufficient water can expose heating surfaces, causing severe overheating and
potentially catastrophic failure.
6. What should an operator do if the boiler water level becomes dangerously low?
A. Follow emergency shutdown procedures and applicable operating instructions
B. Immediately add large amounts of cold water to a severely overheated boiler
C. Increase firing rate
D. Disable the low-water cutoff
Answer: A
Rationale: A severe low-water condition requires immediate action according to the boiler's
approved emergency procedures. Rapid introduction of water into an overheated boiler can be
extremely dangerous.
7. What is the function of a low-water cutoff?
A. Shut down the burner when water level becomes unsafe
B. Increase steam pressure
C. Add chemicals automatically in every system
D. Control building temperature
Answer: A
Rationale: The low-water cutoff protects the boiler from firing without sufficient water.
8. What is the purpose of a pressure gauge?
A. Indicate steam or boiler pressure
B. Measure water volume
C. Measure fuel consumption
D. Detect scale thickness
Answer: A
Rationale: Pressure gauges allow the operator to monitor system pressure.
9. What does boiler blowdown accomplish?
A. Removes concentrated dissolved solids and sludge
B. Increases dissolved solids
C. Adds oxygen to feedwater
D. Raises boiler water level permanently
Answer: A
Rationale: Blowdown removes water containing concentrated impurities and suspended solids.
10. Excessive dissolved solids in boiler water can contribute to:
A. Foaming and carryover
B. Better steam purity
, C. Lower corrosion risk in every case
D. Improved heat transfer
Answer: A
Rationale: High dissolved-solids concentrations can promote foaming and steam carryover.
11. What is steam carryover?
A. Water or boiler-water impurities leaving with the steam
B. Steam returning to the boiler
C. Fuel entering the feedwater
D. Condensate entering the stack
Answer: A
Rationale: Carryover occurs when moisture and/or dissolved or suspended boiler-water material
is transported with steam.
12. What is the purpose of a steam trap?
A. Remove condensate while retaining steam
B. Increase boiler pressure
C. Remove all dissolved oxygen
D. Add water to the boiler
Answer: A
Rationale: Steam traps discharge condensate and non-condensable gases while minimizing live-
steam loss.
13. Condensate is:
A. Water formed when steam loses heat and condenses
B. Fuel oil
C. Boiler scale
D. Compressed air
Answer: A
Rationale: Steam changes back into liquid water when heat is removed.
14. What is the purpose of a feedwater pump?
A. Deliver water to the boiler at sufficient pressure
B. Remove steam from the boiler
C. Reduce combustion air
D. Increase stack draft
Answer: A
Rationale: Feedwater pumps provide the pressure needed to force feedwater into the boiler.
15. Why must feedwater pressure exceed boiler pressure?
A. To allow water to enter the pressurized boiler
