3RD CLASS STATIONARY STEAM ENGINEER LICENSE ACTUAL EXAM NEWEST COMPLETE 200
QUESTIONS AND CORRECT DETAILED ANSWERS| ALREADY GRADED A+
Question 1
Which four factors are fundamental requirements for achieving complete combustion within a
boiler furnace?
A) Carbon, hydrogen, oxygen, and nitrogen
B) Time, temperature, mixture, and atomization
C) Pressure, draft, fuel, and air
D) Radiation, conduction, convection, and induction
E) Velocity, volume, density, and humidity
Correct Answer: B) time, temperature, mixture, and atomization
Rationale: Complete combustion requires that the fuel and air are thoroughly combined
(Mixture), that the fuel is broken into fine droplets (Atomization), that the furnace is hot
enough to sustain the reaction (Temperature), and that the fuel remains in the combustion
zone long enough to burn fully (Time). If any of these are missing, incomplete combustion
occurs, leading to soot and carbon monoxide.
Question 2
If a steam pressure gauge on a boiler indicates 200 PSIG, what is the absolute pressure (PSIA) of
the system?
A) 185.3
B) 200.0
C) 214.7
D) 225.4
E) 14.7
Correct Answer: C) 214.7
Rationale: Absolute pressure (PSIA) is the sum of gauge pressure (PSIG) and atmospheric
pressure. At sea level, atmospheric pressure is approximately 14.7 psi. Therefore, 200 + 14.7
= 214.7 PSIA. Understanding the difference is vital for performing accurate
thermodynamic calculations.
Question 3
A boiler operates at 400 PSI. Its safety valve is set to open at 410 PSI and closes at 398 PSI.
What is the blowdown of this safety valve in psi?
A) 2 psi
B) 10 psi
C) 12 psi
D) 400 psi
E) 15 psi
Correct Answer: C) 12
Rationale: Blowdown is defined as the difference between the pressure at which the safety
valve lifts (pops) and the pressure at which it reseats. In this case, 410 PSI (opening) minus
, Page 2
398 PSI (closing) equals 12 psi of blowdown. This differential prevents the valve from
"chattering" (rapidly opening and closing).
Question 4
In a power plant setting, an oil cooler is most commonly associated with which piece of
equipment when operating a turbo-generator?
A) The deaerator
B) The steam turbine
C) The economizer
D) The centrifugal pump
E) The superheater
Correct Answer: B) steam turbine
Rationale: Steam turbines operating at high speeds generate significant heat in their
bearings. Oil is used for both lubrication and cooling. An oil cooler (heat exchanger) is
required to remove the heat from the oil before it is recirculated to the turbine bearings to
ensure equipment longevity and prevent oil breakdown.
Question 5
A boiler produces 40,000 lbs of steam/hr at 100 PSI. The thermometer indicates a steam
temperature of 500°F. Given that the saturation temperature at 100 PSI is approximately 338°F,
this steam is classified as:
A) Saturated steam
B) Wet steam
C) Superheated steam
D) Flash steam
E) Latent steam
Correct Answer: C) superheated
Rationale: Superheated steam is steam that has been heated to a temperature higher than
its saturation temperature for a given pressure. Since 500°F is significantly higher than the
338°F saturation point at 100 PSI, the steam is superheated. This is done to increase
thermal efficiency and prevent moisture from damaging turbine blades.
Question 6
What is the primary function of an economizer installed in a boiler system?
A) To remove oxygen from the water
B) To add heat to the feedwater using flue gases
C) To cool down the steam before it enters the header
D) To separate water from the steam in the drum
E) To regulate the fuel-to-air ratio
Correct Answer: B) add heat to the feed water
Rationale: An economizer is a heat exchanger located in the breaching (flue gas path). It
captures waste heat from the combustion gases and transfers it to the incoming feedwater.
, Page 3
This increases the overall efficiency of the boiler because less fuel is required to bring the
water to its boiling point.
Question 7
Soot blowers are essential components typically found and used with which type of boiler?
A) Fire tube
B) Scotch Marine
C) Water tube
D) Cast iron sectional
E) Low pressure hot water
Correct Answer: C) water tube
Rationale: Water tube boilers often have complex arrangements of tubes that can
accumulate soot and ash on their exterior (fireside) surfaces. Soot blowers use steam or air
to blast these deposits away, maintaining high heat transfer rates. While some fire tube
boilers use them, they are a standard requirement for large water tube units.
Question 8
What is the most likely cause of localized overheating and subsequent failure of boiler tubes?
A) High water level
B) Low fuel pressure
C) Scale accumulation on the waterside of the tubes
D) Too much excess air
E) Frequent bottom blowdowns
Correct Answer: C) scale on tubes
Rationale: Scale acts as an insulator. When scale builds up on the internal surfaces of the
tubes, it prevents the water from absorbing heat from the tube metal. This causes the tube
metal temperature to rise until it softens or reaches its melting point, leading to a "bag" or
a rupture.
Question 9
What is the primary negative effect of carbon dioxide (CO2) presence in a condensate return
system?
A) It causes the water to become alkaline
B) It leads to "channeling" or "grooving" corrosion in pipes
C) It increases the temperature of the condensate
D) It acts as a lubricant for the pumps
E) It prevents the steam traps from opening
Correct Answer: B) channeling
Rationale: Carbon dioxide dissolves in condensate to form carbonic acid. This acid is highly
corrosive to return piping and typically creates a specific type of corrosion known as
"channeling" or "grooving," which thins the bottom of the pipe until it leaks.
, Page 4
Question 10
Which of the following pumps is classified as a "positive displacement" pump?
A) Centrifugal pump
B) Reciprocating pump
C) Turbine pump
D) Volute pump
E) Diffuser pump
Correct Answer: B) reciprocating
Rationale: A reciprocating pump uses a piston or plunger to move a specific volume of fluid
with every stroke, making it a positive displacement pump. Unlike centrifugal pumps,
which use centrifugal force and can be throttled, positive displacement pumps will build
pressure until something breaks or a relief valve opens if the discharge is blocked.
Question 11
If a boiler is generating 6,000 lbs of steam per hour, approximately how many BTUs per hour is
it producing?
A) 60,000
B) 600,000
C) 6,000,000
D) 12,000,000
E) 3,000,000
Correct Answer: C) 6,000,000
Rationale: In standard boiler calculations, it takes approximately 1,000 BTUs to change 1 lb
of water into steam. Therefore, 6,000 lbs/hr multiplied by 1,000 BTU/lb equals 6,000,000
BTU/hr. This is a common rule of thumb for estimating boiler capacity.
Question 12
What is the specific purpose of performing a "bottom blowdown" on an operating boiler?
A) To remove air from the steam drum
B) To lower the steam pressure quickly
C) To discharge accumulated sludge and sediment
D) To increase the concentration of chemicals
E) To test the safety valve
Correct Answer: C) discharge sludge and sediment
Rationale: Heavy impurities, mud, and precipitated scale-forming salts settle at the lowest
point of the boiler (the mud drum or bottom of the shell). The bottom blowdown is used to
physically eject these solids to prevent them from interfering with heat transfer or clogging
the tubes.
Question 13
According to standard engineering practice and codes, water columns must be connected to the
boiler using a pipe with a minimum diameter of:
QUESTIONS AND CORRECT DETAILED ANSWERS| ALREADY GRADED A+
Question 1
Which four factors are fundamental requirements for achieving complete combustion within a
boiler furnace?
A) Carbon, hydrogen, oxygen, and nitrogen
B) Time, temperature, mixture, and atomization
C) Pressure, draft, fuel, and air
D) Radiation, conduction, convection, and induction
E) Velocity, volume, density, and humidity
Correct Answer: B) time, temperature, mixture, and atomization
Rationale: Complete combustion requires that the fuel and air are thoroughly combined
(Mixture), that the fuel is broken into fine droplets (Atomization), that the furnace is hot
enough to sustain the reaction (Temperature), and that the fuel remains in the combustion
zone long enough to burn fully (Time). If any of these are missing, incomplete combustion
occurs, leading to soot and carbon monoxide.
Question 2
If a steam pressure gauge on a boiler indicates 200 PSIG, what is the absolute pressure (PSIA) of
the system?
A) 185.3
B) 200.0
C) 214.7
D) 225.4
E) 14.7
Correct Answer: C) 214.7
Rationale: Absolute pressure (PSIA) is the sum of gauge pressure (PSIG) and atmospheric
pressure. At sea level, atmospheric pressure is approximately 14.7 psi. Therefore, 200 + 14.7
= 214.7 PSIA. Understanding the difference is vital for performing accurate
thermodynamic calculations.
Question 3
A boiler operates at 400 PSI. Its safety valve is set to open at 410 PSI and closes at 398 PSI.
What is the blowdown of this safety valve in psi?
A) 2 psi
B) 10 psi
C) 12 psi
D) 400 psi
E) 15 psi
Correct Answer: C) 12
Rationale: Blowdown is defined as the difference between the pressure at which the safety
valve lifts (pops) and the pressure at which it reseats. In this case, 410 PSI (opening) minus
, Page 2
398 PSI (closing) equals 12 psi of blowdown. This differential prevents the valve from
"chattering" (rapidly opening and closing).
Question 4
In a power plant setting, an oil cooler is most commonly associated with which piece of
equipment when operating a turbo-generator?
A) The deaerator
B) The steam turbine
C) The economizer
D) The centrifugal pump
E) The superheater
Correct Answer: B) steam turbine
Rationale: Steam turbines operating at high speeds generate significant heat in their
bearings. Oil is used for both lubrication and cooling. An oil cooler (heat exchanger) is
required to remove the heat from the oil before it is recirculated to the turbine bearings to
ensure equipment longevity and prevent oil breakdown.
Question 5
A boiler produces 40,000 lbs of steam/hr at 100 PSI. The thermometer indicates a steam
temperature of 500°F. Given that the saturation temperature at 100 PSI is approximately 338°F,
this steam is classified as:
A) Saturated steam
B) Wet steam
C) Superheated steam
D) Flash steam
E) Latent steam
Correct Answer: C) superheated
Rationale: Superheated steam is steam that has been heated to a temperature higher than
its saturation temperature for a given pressure. Since 500°F is significantly higher than the
338°F saturation point at 100 PSI, the steam is superheated. This is done to increase
thermal efficiency and prevent moisture from damaging turbine blades.
Question 6
What is the primary function of an economizer installed in a boiler system?
A) To remove oxygen from the water
B) To add heat to the feedwater using flue gases
C) To cool down the steam before it enters the header
D) To separate water from the steam in the drum
E) To regulate the fuel-to-air ratio
Correct Answer: B) add heat to the feed water
Rationale: An economizer is a heat exchanger located in the breaching (flue gas path). It
captures waste heat from the combustion gases and transfers it to the incoming feedwater.
, Page 3
This increases the overall efficiency of the boiler because less fuel is required to bring the
water to its boiling point.
Question 7
Soot blowers are essential components typically found and used with which type of boiler?
A) Fire tube
B) Scotch Marine
C) Water tube
D) Cast iron sectional
E) Low pressure hot water
Correct Answer: C) water tube
Rationale: Water tube boilers often have complex arrangements of tubes that can
accumulate soot and ash on their exterior (fireside) surfaces. Soot blowers use steam or air
to blast these deposits away, maintaining high heat transfer rates. While some fire tube
boilers use them, they are a standard requirement for large water tube units.
Question 8
What is the most likely cause of localized overheating and subsequent failure of boiler tubes?
A) High water level
B) Low fuel pressure
C) Scale accumulation on the waterside of the tubes
D) Too much excess air
E) Frequent bottom blowdowns
Correct Answer: C) scale on tubes
Rationale: Scale acts as an insulator. When scale builds up on the internal surfaces of the
tubes, it prevents the water from absorbing heat from the tube metal. This causes the tube
metal temperature to rise until it softens or reaches its melting point, leading to a "bag" or
a rupture.
Question 9
What is the primary negative effect of carbon dioxide (CO2) presence in a condensate return
system?
A) It causes the water to become alkaline
B) It leads to "channeling" or "grooving" corrosion in pipes
C) It increases the temperature of the condensate
D) It acts as a lubricant for the pumps
E) It prevents the steam traps from opening
Correct Answer: B) channeling
Rationale: Carbon dioxide dissolves in condensate to form carbonic acid. This acid is highly
corrosive to return piping and typically creates a specific type of corrosion known as
"channeling" or "grooving," which thins the bottom of the pipe until it leaks.
, Page 4
Question 10
Which of the following pumps is classified as a "positive displacement" pump?
A) Centrifugal pump
B) Reciprocating pump
C) Turbine pump
D) Volute pump
E) Diffuser pump
Correct Answer: B) reciprocating
Rationale: A reciprocating pump uses a piston or plunger to move a specific volume of fluid
with every stroke, making it a positive displacement pump. Unlike centrifugal pumps,
which use centrifugal force and can be throttled, positive displacement pumps will build
pressure until something breaks or a relief valve opens if the discharge is blocked.
Question 11
If a boiler is generating 6,000 lbs of steam per hour, approximately how many BTUs per hour is
it producing?
A) 60,000
B) 600,000
C) 6,000,000
D) 12,000,000
E) 3,000,000
Correct Answer: C) 6,000,000
Rationale: In standard boiler calculations, it takes approximately 1,000 BTUs to change 1 lb
of water into steam. Therefore, 6,000 lbs/hr multiplied by 1,000 BTU/lb equals 6,000,000
BTU/hr. This is a common rule of thumb for estimating boiler capacity.
Question 12
What is the specific purpose of performing a "bottom blowdown" on an operating boiler?
A) To remove air from the steam drum
B) To lower the steam pressure quickly
C) To discharge accumulated sludge and sediment
D) To increase the concentration of chemicals
E) To test the safety valve
Correct Answer: C) discharge sludge and sediment
Rationale: Heavy impurities, mud, and precipitated scale-forming salts settle at the lowest
point of the boiler (the mud drum or bottom of the shell). The bottom blowdown is used to
physically eject these solids to prevent them from interfering with heat transfer or clogging
the tubes.
Question 13
According to standard engineering practice and codes, water columns must be connected to the
boiler using a pipe with a minimum diameter of:
