661-LA 661 Louisiana (New Orleans)
Second Class Stationary Boilers Practice
Exam 300 Questions and Correct Answers
Based on New Orleans Boiler Code and
ASME Standards 2026 Edition
Q1. The primary purpose of boiler water treatment in stationary boilers is to:
A. Increase water hardness
B. Prevent scale and corrosion
C. Enhance fuel combustion
D. Reduce boiler pressure
Answer: B. Prevent scale and corrosion
Rationale: Boiler water treatment is primarily aimed at preventing scale formation and
corrosion in boiler systems, ensuring safe and efficient operation .
Q2. Which chemical is commonly used as an oxygen scavenger in boiler water
treatment?
A. Sodium chloride
B. Hydrazine
C. Calcium carbonate
D. Ammonia
Answer: B. Hydrazine
Rationale: Hydrazine is commonly used as an oxygen scavenger to remove dissolved
oxygen from feedwater, preventing corrosion in boiler systems .
Q3. What is the primary purpose of a safety valve on a steam boiler?
,A. Control the operating pressure
B. Relieve excess pressure to prevent over-pressurization and rupture
C. Regulate the water level
D. Vent gases during startup
Answer: B. Relieve excess pressure to prevent over-pressurization and rupture
Rationale: Safety valves are critical overpressure protection devices designed to open
automatically at a set pressure and discharge enough steam to prevent pressure from
rising more than a specified amount above the MAWP .
Q4. What is the minimum number of safety valves required on a boiler with more
than 500 square feet of heating surface?
A. One
B. Two
C. Three
D. Four
Answer: B. Two
Rationale: ASME Code requires at least two safety valves on boilers with over 500
square feet of heating surface to provide adequate overpressure protection and
redundancy .
Q5. The process of removing sediment and concentrated solids from the bottom of
a boiler is called:
A. Surface blowdown
B. Bottom blowdown
C. Skimming
D. Scavenging
Answer: B. Bottom blowdown
,Rationale: Bottom blowdown involves opening valves on the bottom of the boiler or
water drum to remove sludge, sediment, and precipitated solids that settle at the lowest
points .
Q6. A "hydrostatic test" on a boiler is performed using:
A. Steam at operating pressure
B. Air at 1.5 times MAWP
C. Water at 1.5 times MAWP
D. Oil at design pressure
Answer: C. Water at 1.5 times MAWP
Rationale: A hydrostatic test verifies the strength and leak tightness of a boiler by filling
it completely with water and pressurizing to 1.5 times the MAWP, held for a specified
time .
Q7. What is the most common type of safety valve used on steam boilers?
A. Spring-loaded
B. Weight-loaded lever
C. Pilot-operated
D. Bellows-type
Answer: A. Spring-loaded
Rationale: Spring-loaded safety valves are the standard for stationary boilers due to
their reliability, compact size, and ability to be sealed and tagged .
Q8. During a boiler "dry lay-up," the boiler is:
A. Filled with treated water
B. Drained, cleaned, dried, and desiccants are placed inside
C. Kept at normal operating temperature
D. Used only for hot water
Answer: B. Drained, cleaned, dried, and desiccants are placed inside
, Rationale: Dry lay-up involves completely drying the boiler interior and using moisture-
absorbing desiccants to prevent corrosion during extended out-of-service periods .
Q9. The phenomenon where water droplets are carried over into the steam outlet
is called:
A. Foaming
B. Priming
C. Scaling
D. Sludging
Answer: B. Priming
Rationale: Priming is the violent eruption of water into the steam outlet, often due to
high water level, sudden load changes, or improper boiler design/operation .
Q10. The chemical used to chemically deaerate boiler feedwater by scavenging
oxygen is:
A. Sodium hydroxide
B. Sodium sulfite
C. Phosphates
D. Polymers
Answer: B. Sodium sulfite
Rationale: Sodium sulfite is a common oxygen scavenger that reacts with dissolved
oxygen to form sodium sulfate, removing oxygen from the feedwater to prevent
corrosion .
Q11. A "water column" on a boiler serves to:
A. Cool the steam
B. Provide a calm water area for accurate gauge glass reading and connection of
controls
Second Class Stationary Boilers Practice
Exam 300 Questions and Correct Answers
Based on New Orleans Boiler Code and
ASME Standards 2026 Edition
Q1. The primary purpose of boiler water treatment in stationary boilers is to:
A. Increase water hardness
B. Prevent scale and corrosion
C. Enhance fuel combustion
D. Reduce boiler pressure
Answer: B. Prevent scale and corrosion
Rationale: Boiler water treatment is primarily aimed at preventing scale formation and
corrosion in boiler systems, ensuring safe and efficient operation .
Q2. Which chemical is commonly used as an oxygen scavenger in boiler water
treatment?
A. Sodium chloride
B. Hydrazine
C. Calcium carbonate
D. Ammonia
Answer: B. Hydrazine
Rationale: Hydrazine is commonly used as an oxygen scavenger to remove dissolved
oxygen from feedwater, preventing corrosion in boiler systems .
Q3. What is the primary purpose of a safety valve on a steam boiler?
,A. Control the operating pressure
B. Relieve excess pressure to prevent over-pressurization and rupture
C. Regulate the water level
D. Vent gases during startup
Answer: B. Relieve excess pressure to prevent over-pressurization and rupture
Rationale: Safety valves are critical overpressure protection devices designed to open
automatically at a set pressure and discharge enough steam to prevent pressure from
rising more than a specified amount above the MAWP .
Q4. What is the minimum number of safety valves required on a boiler with more
than 500 square feet of heating surface?
A. One
B. Two
C. Three
D. Four
Answer: B. Two
Rationale: ASME Code requires at least two safety valves on boilers with over 500
square feet of heating surface to provide adequate overpressure protection and
redundancy .
Q5. The process of removing sediment and concentrated solids from the bottom of
a boiler is called:
A. Surface blowdown
B. Bottom blowdown
C. Skimming
D. Scavenging
Answer: B. Bottom blowdown
,Rationale: Bottom blowdown involves opening valves on the bottom of the boiler or
water drum to remove sludge, sediment, and precipitated solids that settle at the lowest
points .
Q6. A "hydrostatic test" on a boiler is performed using:
A. Steam at operating pressure
B. Air at 1.5 times MAWP
C. Water at 1.5 times MAWP
D. Oil at design pressure
Answer: C. Water at 1.5 times MAWP
Rationale: A hydrostatic test verifies the strength and leak tightness of a boiler by filling
it completely with water and pressurizing to 1.5 times the MAWP, held for a specified
time .
Q7. What is the most common type of safety valve used on steam boilers?
A. Spring-loaded
B. Weight-loaded lever
C. Pilot-operated
D. Bellows-type
Answer: A. Spring-loaded
Rationale: Spring-loaded safety valves are the standard for stationary boilers due to
their reliability, compact size, and ability to be sealed and tagged .
Q8. During a boiler "dry lay-up," the boiler is:
A. Filled with treated water
B. Drained, cleaned, dried, and desiccants are placed inside
C. Kept at normal operating temperature
D. Used only for hot water
Answer: B. Drained, cleaned, dried, and desiccants are placed inside
, Rationale: Dry lay-up involves completely drying the boiler interior and using moisture-
absorbing desiccants to prevent corrosion during extended out-of-service periods .
Q9. The phenomenon where water droplets are carried over into the steam outlet
is called:
A. Foaming
B. Priming
C. Scaling
D. Sludging
Answer: B. Priming
Rationale: Priming is the violent eruption of water into the steam outlet, often due to
high water level, sudden load changes, or improper boiler design/operation .
Q10. The chemical used to chemically deaerate boiler feedwater by scavenging
oxygen is:
A. Sodium hydroxide
B. Sodium sulfite
C. Phosphates
D. Polymers
Answer: B. Sodium sulfite
Rationale: Sodium sulfite is a common oxygen scavenger that reacts with dissolved
oxygen to form sodium sulfate, removing oxygen from the feedwater to prevent
corrosion .
Q11. A "water column" on a boiler serves to:
A. Cool the steam
B. Provide a calm water area for accurate gauge glass reading and connection of
controls
