Ohio Stationary Steam Engineer – 3rd Class Practice
Exam Practice Questions And Correct Answers (Verified
Answers) Plus Rationales 2026 Q&A | Instant Download
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1. What is the primary purpose of a safety valve on a boiler?
A. To control feedwater flow
B. To prevent boiler overpressure
C. To regulate steam flow
D. To maintain temperature
Rationale: The safety valve automatically releases steam when pressure exceeds the set limit, preventing
explosions.
2. The term “superheated steam” refers to steam that:
A. Contains water droplets
B. Has a pressure above atmospheric
C. Has been heated beyond the saturation temperature
D. Is saturated with water vapor
Rationale: Superheated steam is produced when saturated steam is heated without increasing pressure.
3. The function of the boiler feedwater pump is to:
A. Remove condensate
B. Increase steam pressure
C. Deliver water to the boiler under pressure
D. Control combustion
Rationale: Feedwater pumps supply water to maintain boiler water level under steam pressure.
4. The water gauge glass on a boiler shows:
A. Steam temperature
B. The level of water in the boiler
C. Feedwater pressure
D. Fuel-to-air ratio
Rationale: Operators use the gauge glass to visually confirm the boiler’s water level.
,5. What is the main function of a blowdown valve?
A. Release steam
B. Remove sludge and sediment from the boiler
C. Regulate steam flow
D. Increase boiler pressure
Rationale: Blowdown removes impurities and sediment, preventing scale buildup.
6. The maximum allowable working pressure (MAWP) is found on the:
A. Feedwater tank
B. Boiler nameplate
C. Pressure gauge
D. Water column
Rationale: The MAWP is stamped on the boiler nameplate as required by ASME Code.
7. Low-water cutoffs must be tested:
A. Annually
B. Daily or as per operating schedule
C. Every 90 days
D. Every 6 months
Rationale: Frequent testing ensures the device properly shuts the burner down during low-water
conditions.
8. The fusible plug is designed to:
A. Melt at a specific temperature and release pressure
B. Measure boiler pressure
C. Maintain feedwater temperature
D. Control blowdown
Rationale: It provides a last-resort safety measure against low-water conditions by melting and venting
steam.
9. The purpose of a steam trap is to:
A. Release steam
B. Remove condensate without losing steam
C. Control boiler pressure
D. Maintain feedwater flow
Rationale: Steam traps automatically discharge condensate from steam lines while retaining steam.
, 10. A high stack temperature usually indicates:
A. Efficient combustion
B. Poor heat transfer due to soot or scale
C. Proper air-fuel ratio
D. Normal operation
Rationale: High flue gas temperatures mean heat isn’t transferring properly — often from dirty heating
surfaces.
11. Scale inside a boiler acts as:
A. A lubricant
B. An insulator reducing heat transfer
C. A corrosion inhibitor
D. A heat exchanger
Rationale: Scale reduces heat transfer efficiency and can cause metal overheating.
12. When starting a boiler from a cold state, the operator should:
A. Fire immediately at full load
B. Warm it up gradually
C. Leave vents closed
D. Fill it completely with water
Rationale: Slow warm-up prevents thermal stress and cracking.
13. The “try cock” on a boiler is used to:
A. Drain condensate
B. Check steam purity
C. Verify water level manually
D. Adjust pressure
Rationale: Try cocks are test fittings for confirming water level if the gauge glass fails.
14. The primary chemical used to prevent boiler scale is:
A. Soda ash
B. Salt
C. Phosphate
D. Chlorine
Rationale: Phosphates react with hardness minerals, forming soft sludge easily removed by blowdown.
Exam Practice Questions And Correct Answers (Verified
Answers) Plus Rationales 2026 Q&A | Instant Download
1. What is the primary purpose of a safety valve on a boiler?
A. To control feedwater flow
B. To prevent boiler overpressure
C. To regulate steam flow
D. To maintain temperature
Rationale: The safety valve automatically releases steam when pressure exceeds the set limit, preventing
explosions.
2. The term “superheated steam” refers to steam that:
A. Contains water droplets
B. Has a pressure above atmospheric
C. Has been heated beyond the saturation temperature
D. Is saturated with water vapor
Rationale: Superheated steam is produced when saturated steam is heated without increasing pressure.
3. The function of the boiler feedwater pump is to:
A. Remove condensate
B. Increase steam pressure
C. Deliver water to the boiler under pressure
D. Control combustion
Rationale: Feedwater pumps supply water to maintain boiler water level under steam pressure.
4. The water gauge glass on a boiler shows:
A. Steam temperature
B. The level of water in the boiler
C. Feedwater pressure
D. Fuel-to-air ratio
Rationale: Operators use the gauge glass to visually confirm the boiler’s water level.
,5. What is the main function of a blowdown valve?
A. Release steam
B. Remove sludge and sediment from the boiler
C. Regulate steam flow
D. Increase boiler pressure
Rationale: Blowdown removes impurities and sediment, preventing scale buildup.
6. The maximum allowable working pressure (MAWP) is found on the:
A. Feedwater tank
B. Boiler nameplate
C. Pressure gauge
D. Water column
Rationale: The MAWP is stamped on the boiler nameplate as required by ASME Code.
7. Low-water cutoffs must be tested:
A. Annually
B. Daily or as per operating schedule
C. Every 90 days
D. Every 6 months
Rationale: Frequent testing ensures the device properly shuts the burner down during low-water
conditions.
8. The fusible plug is designed to:
A. Melt at a specific temperature and release pressure
B. Measure boiler pressure
C. Maintain feedwater temperature
D. Control blowdown
Rationale: It provides a last-resort safety measure against low-water conditions by melting and venting
steam.
9. The purpose of a steam trap is to:
A. Release steam
B. Remove condensate without losing steam
C. Control boiler pressure
D. Maintain feedwater flow
Rationale: Steam traps automatically discharge condensate from steam lines while retaining steam.
, 10. A high stack temperature usually indicates:
A. Efficient combustion
B. Poor heat transfer due to soot or scale
C. Proper air-fuel ratio
D. Normal operation
Rationale: High flue gas temperatures mean heat isn’t transferring properly — often from dirty heating
surfaces.
11. Scale inside a boiler acts as:
A. A lubricant
B. An insulator reducing heat transfer
C. A corrosion inhibitor
D. A heat exchanger
Rationale: Scale reduces heat transfer efficiency and can cause metal overheating.
12. When starting a boiler from a cold state, the operator should:
A. Fire immediately at full load
B. Warm it up gradually
C. Leave vents closed
D. Fill it completely with water
Rationale: Slow warm-up prevents thermal stress and cracking.
13. The “try cock” on a boiler is used to:
A. Drain condensate
B. Check steam purity
C. Verify water level manually
D. Adjust pressure
Rationale: Try cocks are test fittings for confirming water level if the gauge glass fails.
14. The primary chemical used to prevent boiler scale is:
A. Soda ash
B. Salt
C. Phosphate
D. Chlorine
Rationale: Phosphates react with hardness minerals, forming soft sludge easily removed by blowdown.
