Page 1 of 200
DC Third Class Stationary Boilers (323) Practice
Exam Questions & Answers VERIFIED
SOLUTIONS LATEST UPDATE THIS YEAR
DC Third Class Stationary Boilers (323) Practice Exam
This comprehensive practice exam is designed to help you prepare for the Washington D.C.
Third Class Stationary Boilers (Exam 323) licensing examination. It covers boiler fundamentals,
steam systems, fuel combustion, water treatment, safety devices, and relevant codes (ASME,
OSHA). A passing score on this exam is typically 70%.
Domain 1: Boiler Basics & Design
Question 1
Which type of boiler contains water inside the tubes with hot combustion gases passing
outside?
A) Fire-tube boiler
B) Water-tube boiler
C) Cast iron sectional boiler
D) Electric boiler
Answer: B
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In a water-tube boiler, water circulates inside the tubes while the hot combustion gases pass
around them. This design allows for much higher steam pressures than fire-tube designs.
Question 2
What is the primary function of a safety valve on a boiler?
A) To regulate the boiler's operating pressure
B) To automatically release steam to prevent over-pressurization
C) To remove dissolved solids from the boiler water
D) To vent air during the startup process
Answer: B
A safety valve is a spring-loaded device designed to automatically open at a set pressure to
prevent the boiler from exceeding its Maximum Allowable Working Pressure (MAWP).
,Page 3 of 200
Question 3
What does "MAWP" stand for?
A) Minimum Acceptable Water Pressure
B) Maximum Allowable Working Pressure
C) Maximum Atmospheric Water Pressure
D) Minimum Allowable Working Pressure
Answer: B
MAWP is the maximum pressure at which a boiler is allowed to operate safely. It is determined
by the boiler's design and construction.
Question 4
How many degrees of superheat does steam have if its temperature is 500°F and the saturation
temperature at the same pressure is 338°F?
A) 162°F
, Page 4 of 200
B) 338°F
C) 500°F
D) 838°F
Answer: A
Superheat is the difference between the actual steam temperature and the saturation
temperature. 500°F – 338°F = 162°F of superheat.
Question 5
An economizer is installed on a boiler primarily to:
A) Reduce fuel consumption by pre-heating the feedwater
B) Increase the pressure in the steam drum
C) Lower the temperature of the flue gas
D) Increase the steam output
Answer: A
DC Third Class Stationary Boilers (323) Practice
Exam Questions & Answers VERIFIED
SOLUTIONS LATEST UPDATE THIS YEAR
DC Third Class Stationary Boilers (323) Practice Exam
This comprehensive practice exam is designed to help you prepare for the Washington D.C.
Third Class Stationary Boilers (Exam 323) licensing examination. It covers boiler fundamentals,
steam systems, fuel combustion, water treatment, safety devices, and relevant codes (ASME,
OSHA). A passing score on this exam is typically 70%.
Domain 1: Boiler Basics & Design
Question 1
Which type of boiler contains water inside the tubes with hot combustion gases passing
outside?
A) Fire-tube boiler
B) Water-tube boiler
C) Cast iron sectional boiler
D) Electric boiler
Answer: B
,Page 2 of 200
In a water-tube boiler, water circulates inside the tubes while the hot combustion gases pass
around them. This design allows for much higher steam pressures than fire-tube designs.
Question 2
What is the primary function of a safety valve on a boiler?
A) To regulate the boiler's operating pressure
B) To automatically release steam to prevent over-pressurization
C) To remove dissolved solids from the boiler water
D) To vent air during the startup process
Answer: B
A safety valve is a spring-loaded device designed to automatically open at a set pressure to
prevent the boiler from exceeding its Maximum Allowable Working Pressure (MAWP).
,Page 3 of 200
Question 3
What does "MAWP" stand for?
A) Minimum Acceptable Water Pressure
B) Maximum Allowable Working Pressure
C) Maximum Atmospheric Water Pressure
D) Minimum Allowable Working Pressure
Answer: B
MAWP is the maximum pressure at which a boiler is allowed to operate safely. It is determined
by the boiler's design and construction.
Question 4
How many degrees of superheat does steam have if its temperature is 500°F and the saturation
temperature at the same pressure is 338°F?
A) 162°F
, Page 4 of 200
B) 338°F
C) 500°F
D) 838°F
Answer: A
Superheat is the difference between the actual steam temperature and the saturation
temperature. 500°F – 338°F = 162°F of superheat.
Question 5
An economizer is installed on a boiler primarily to:
A) Reduce fuel consumption by pre-heating the feedwater
B) Increase the pressure in the steam drum
C) Lower the temperature of the flue gas
D) Increase the steam output
Answer: A
