3rd Class Stationary Steam Engineer License Prep
3RD CLASS STATIONARY STEAM ENGINEER LICENSE PREP
NEWEST 2026/2027 ACTUAL EXAM COMPLETE 250 QUESTIONS
AND CORRECT DETAILED ANSWERS (VERIFIED ANSWERS) WITH
DETAILED RATIONALES |ALREADY GRADED A+||BRAND NEW
VERSION!!
The economizer on a boiler is used to _______
a) Increase steam pressure
b) Remove dissolved gases
c) Add heat to the feedwater
d) Reduce flue gas velocity
Correct Answer: c) Add heat to the feedwater
Explanation: An economizer captures waste heat from flue gases to preheat
feedwater before it enters the boiler. This increases efficiency by reducing the
energy required to convert water into steam.
Blowers are normally used with________ boilers
a) Fire tube
b) Electric
c) Cast iron
d) Water tube
Correct Answer: d) Water tube
Explanation: Water tube boilers often use soot blowers to remove soot and ash
from tube surfaces. This maintains efficient heat transfer and prevents
overheating.
1|Page
, 3rd Class Stationary Steam Engineer License Prep
Overheating of tubes on a boiler can be caused by________
a) High feedwater temperature
b) Excess draft
c) Scale on tubes
d) Low steam pressure
Correct Answer: c) Scale on tubes
Explanation: Scale acts as an insulator, preventing proper heat transfer. This
causes localized overheating, which can weaken and eventually rupture boiler
tubes.
Carbon dioxide in a condensate return system causes_________
a) Scaling
b) Foaming
c) Channeling
d) Corrosion
Correct Answer: d) Corrosion
Explanation: Carbon dioxide dissolves in condensate to form carbonic acid, which
lowers pH and causes corrosion in piping and equipment.
A ________ pump is a positive displacement pump
a) Centrifugal
b) Axial flow
c) Reciprocating
d) Turbine
Correct Answer: c) Reciprocating
Explanation: Reciprocating pumps move a fixed volume of fluid with each stroke,
making them positive displacement pumps. They are commonly used where
precise flow is required.
2|Page
, 3rd Class Stationary Steam Engineer License Prep
A boiler generating 6000 lb of steam/hr produces _______ BTU/hr
a) 3,000,000
b) 6,000,000
c) 9,000,000
d) 12,000,000
Correct Answer: b) 6,000,000
Explanation: A common approximation is that 1 lb of steam equals about 1000
BTU. Therefore, 6000 lb/hr produces approximately 6,000,000 BTU/hr.
A bottom blowdown is performed on a boiler to _____
a) Reduce pressure
b) Remove dissolved gases
c) Discharge sludge and sediment
d) Increase efficiency
Correct Answer: c) Discharge sludge and sediment
Explanation: Bottom blowdown removes accumulated solids like sludge and
sediment from the lowest part of the boiler, preventing buildup that could lead to
overheating or damage.
Water columns are connected to the boiler with a minimum of _______" pipe
a) 1
b) 2
c) 3/4
d) 1/2
Correct Answer: a) 1
3|Page
, 3rd Class Stationary Steam Engineer License Prep
Explanation: Proper pipe sizing ensures accurate water level readings and safe
operation. A minimum of 1-inch piping allows sufficient flow and prevents
clogging.
The minimum size of a water column blowdown valve is_______"
a) 1
b) 1/2
c) 3/4
d) 2
Correct Answer: c) 3/4
Explanation: A 3/4-inch valve ensures effective blowdown of sediment and proper
maintenance of the water column.
The maximum size bottom blowdown valve on a boiler is_________"
a) 1
b) 2
c) 2 1/2
d) 3
Correct Answer: c) 2 1/2
Explanation: This size provides sufficient flow for removing sludge while
maintaining safe control over discharge.
Which of the following are necessary for complete combustion?
a) Pressure, velocity, and ignition
b) Time, temperature, mixture, and atomization
c) Oxygen, fuel, and turbulence
d) Heat, draft, and excess air
Correct Answer: b) Time, temperature, mixture, and atomization
4|Page
3RD CLASS STATIONARY STEAM ENGINEER LICENSE PREP
NEWEST 2026/2027 ACTUAL EXAM COMPLETE 250 QUESTIONS
AND CORRECT DETAILED ANSWERS (VERIFIED ANSWERS) WITH
DETAILED RATIONALES |ALREADY GRADED A+||BRAND NEW
VERSION!!
The economizer on a boiler is used to _______
a) Increase steam pressure
b) Remove dissolved gases
c) Add heat to the feedwater
d) Reduce flue gas velocity
Correct Answer: c) Add heat to the feedwater
Explanation: An economizer captures waste heat from flue gases to preheat
feedwater before it enters the boiler. This increases efficiency by reducing the
energy required to convert water into steam.
Blowers are normally used with________ boilers
a) Fire tube
b) Electric
c) Cast iron
d) Water tube
Correct Answer: d) Water tube
Explanation: Water tube boilers often use soot blowers to remove soot and ash
from tube surfaces. This maintains efficient heat transfer and prevents
overheating.
1|Page
, 3rd Class Stationary Steam Engineer License Prep
Overheating of tubes on a boiler can be caused by________
a) High feedwater temperature
b) Excess draft
c) Scale on tubes
d) Low steam pressure
Correct Answer: c) Scale on tubes
Explanation: Scale acts as an insulator, preventing proper heat transfer. This
causes localized overheating, which can weaken and eventually rupture boiler
tubes.
Carbon dioxide in a condensate return system causes_________
a) Scaling
b) Foaming
c) Channeling
d) Corrosion
Correct Answer: d) Corrosion
Explanation: Carbon dioxide dissolves in condensate to form carbonic acid, which
lowers pH and causes corrosion in piping and equipment.
A ________ pump is a positive displacement pump
a) Centrifugal
b) Axial flow
c) Reciprocating
d) Turbine
Correct Answer: c) Reciprocating
Explanation: Reciprocating pumps move a fixed volume of fluid with each stroke,
making them positive displacement pumps. They are commonly used where
precise flow is required.
2|Page
, 3rd Class Stationary Steam Engineer License Prep
A boiler generating 6000 lb of steam/hr produces _______ BTU/hr
a) 3,000,000
b) 6,000,000
c) 9,000,000
d) 12,000,000
Correct Answer: b) 6,000,000
Explanation: A common approximation is that 1 lb of steam equals about 1000
BTU. Therefore, 6000 lb/hr produces approximately 6,000,000 BTU/hr.
A bottom blowdown is performed on a boiler to _____
a) Reduce pressure
b) Remove dissolved gases
c) Discharge sludge and sediment
d) Increase efficiency
Correct Answer: c) Discharge sludge and sediment
Explanation: Bottom blowdown removes accumulated solids like sludge and
sediment from the lowest part of the boiler, preventing buildup that could lead to
overheating or damage.
Water columns are connected to the boiler with a minimum of _______" pipe
a) 1
b) 2
c) 3/4
d) 1/2
Correct Answer: a) 1
3|Page
, 3rd Class Stationary Steam Engineer License Prep
Explanation: Proper pipe sizing ensures accurate water level readings and safe
operation. A minimum of 1-inch piping allows sufficient flow and prevents
clogging.
The minimum size of a water column blowdown valve is_______"
a) 1
b) 1/2
c) 3/4
d) 2
Correct Answer: c) 3/4
Explanation: A 3/4-inch valve ensures effective blowdown of sediment and proper
maintenance of the water column.
The maximum size bottom blowdown valve on a boiler is_________"
a) 1
b) 2
c) 2 1/2
d) 3
Correct Answer: c) 2 1/2
Explanation: This size provides sufficient flow for removing sludge while
maintaining safe control over discharge.
Which of the following are necessary for complete combustion?
a) Pressure, velocity, and ignition
b) Time, temperature, mixture, and atomization
c) Oxygen, fuel, and turbulence
d) Heat, draft, and excess air
Correct Answer: b) Time, temperature, mixture, and atomization
4|Page
