3B2 POWER ENGINEER EXAM/3B2 POWER
ENGINEER EXAM COMPLETE QUESTIONS AND
CORRECT DETAILED ANSWERS A NEW UPDATED
VERSION LATEST 2026-2027/3B2 POWER ENGINEER
EXAM LATEST UPDATED VERSION 2026|FULL
REVISED EXAM
The primary function of an economizer in a power boiler is to:
a) Reduce flue gas temperature before the stack
b) Preheat combustion air
c) Preheat feedwater using flue gas heat
d) Increase steam temperature
Answer: c) Preheat feedwater using flue gas heat
An economizer recovers waste heat from flue gases to raise feedwater temperature,
improving overall thermal efficiency by reducing the fuel required for evaporation.
When conducting a bottom blowdown on a boiler, the correct procedure is to:
a) Open the quick-opening valve first, then the slow-opening valve
b) Open the slow-opening valve first, then the quick-opening valve
c) Open both valves simultaneously fully
d) Only open the slow-opening valve
,Answer: b) Open the slow-opening valve first, then the quick-opening valve
Opening the slow-opening valve first protects the quick-opening valve from erosion
and wear; the quick-opening valve is then opened fully to allow rapid discharge, and
the slow-opening valve is used for throttling to prevent water hammer.
A boiler operating at 1500 kPa has a water level that falls rapidly when the
burner is on. The immediate action to take is:
a) Increase feedwater flow
b) Shut off the burner and close the main steam stop valve
c) Open the blowdown valve to remove sludge
d) Reduce the firing rate and check the feed pump
Answer: b) Shut off the burner and close the main steam stop valve
Rapidly falling water level with the burner on indicates a possible tube rupture or
major leak; shutting off the burner and isolating the boiler from the steam header
prevents thermal shock and further damage while allowing the water level to be
assessed safely.
The minimum required hydrostatic test pressure for a new power boiler
operating at 2000 kPa is approximately:
a) 2000 kPa
b) 2500 kPa
c) 3000 kPa
d) 4000 kPa
Answer: c) 3000 kPa
Hydrostatic test pressure for a new boiler is typically 1.5 times the maximum
allowable working pressure (MAWP), so 2000 kPa × 1.5 = 3000 kPa, ensuring the
integrity of the pressure vessel before commissioning.
,A sudden drop in steam pressure with a corresponding rise in water level in a
firetube boiler is most likely caused by:
a) Excessive blowdown
b) A burst tube
c) Feedwater regulator failure (stuck open)
d) Pressure gauge malfunction
Answer: b) A burst tube
A burst tube allows steam to escape into the water space, reducing pressure while the
released steam bubbles raise the water level artificially, a classic sign of tube failure
in firetube boilers.
The maximum allowable total dissolved solids (TDS) in a high-pressure
watertube boiler is generally:
a) 50–150 ppm
b) 500–1000 ppm
c) 2000–3500 ppm
d) 5000–8000 ppm
Answer: c) 2000–3500 ppm
High-pressure watertube boilers operate with tighter TDS limits to prevent carryover
and scale; 2000–3500 ppm is typical for many industrial units, though specific
limits depend on boiler design and water treatment.
A gauge glass showing a false high water level may be caused by:
a) A blocked steam connection
b) A leaking drain valve
, c) Low boiler pressure
d) Excessive feedwater temperature
Answer: a) A blocked steam connection
If the steam connection to the gauge glass is blocked, steam cannot enter to equalize
pressure, so water is pushed higher in the glass than the actual drum level, giving a
dangerously false reading.
The term "furnace volume heat release rate" is expressed in:
a) kW/m²
b) kJ/kg
c) kW/m³
d) MPa
Answer: c) kW/m³
Furnace volume heat release rate is the amount of heat released per unit volume of
the furnace per unit time, typically in kW/m³, and is a critical design parameter to
avoid slagging and flame impingement.
A boiler safety valve set to pop at 2800 kPa has a blowdown of 4%. At what
pressure will it reseat?
a) 2688 kPa
b) 2720 kPa
c) 2800 kPa
d) 2912 kPa
Answer: a) 2688 kPa
ENGINEER EXAM COMPLETE QUESTIONS AND
CORRECT DETAILED ANSWERS A NEW UPDATED
VERSION LATEST 2026-2027/3B2 POWER ENGINEER
EXAM LATEST UPDATED VERSION 2026|FULL
REVISED EXAM
The primary function of an economizer in a power boiler is to:
a) Reduce flue gas temperature before the stack
b) Preheat combustion air
c) Preheat feedwater using flue gas heat
d) Increase steam temperature
Answer: c) Preheat feedwater using flue gas heat
An economizer recovers waste heat from flue gases to raise feedwater temperature,
improving overall thermal efficiency by reducing the fuel required for evaporation.
When conducting a bottom blowdown on a boiler, the correct procedure is to:
a) Open the quick-opening valve first, then the slow-opening valve
b) Open the slow-opening valve first, then the quick-opening valve
c) Open both valves simultaneously fully
d) Only open the slow-opening valve
,Answer: b) Open the slow-opening valve first, then the quick-opening valve
Opening the slow-opening valve first protects the quick-opening valve from erosion
and wear; the quick-opening valve is then opened fully to allow rapid discharge, and
the slow-opening valve is used for throttling to prevent water hammer.
A boiler operating at 1500 kPa has a water level that falls rapidly when the
burner is on. The immediate action to take is:
a) Increase feedwater flow
b) Shut off the burner and close the main steam stop valve
c) Open the blowdown valve to remove sludge
d) Reduce the firing rate and check the feed pump
Answer: b) Shut off the burner and close the main steam stop valve
Rapidly falling water level with the burner on indicates a possible tube rupture or
major leak; shutting off the burner and isolating the boiler from the steam header
prevents thermal shock and further damage while allowing the water level to be
assessed safely.
The minimum required hydrostatic test pressure for a new power boiler
operating at 2000 kPa is approximately:
a) 2000 kPa
b) 2500 kPa
c) 3000 kPa
d) 4000 kPa
Answer: c) 3000 kPa
Hydrostatic test pressure for a new boiler is typically 1.5 times the maximum
allowable working pressure (MAWP), so 2000 kPa × 1.5 = 3000 kPa, ensuring the
integrity of the pressure vessel before commissioning.
,A sudden drop in steam pressure with a corresponding rise in water level in a
firetube boiler is most likely caused by:
a) Excessive blowdown
b) A burst tube
c) Feedwater regulator failure (stuck open)
d) Pressure gauge malfunction
Answer: b) A burst tube
A burst tube allows steam to escape into the water space, reducing pressure while the
released steam bubbles raise the water level artificially, a classic sign of tube failure
in firetube boilers.
The maximum allowable total dissolved solids (TDS) in a high-pressure
watertube boiler is generally:
a) 50–150 ppm
b) 500–1000 ppm
c) 2000–3500 ppm
d) 5000–8000 ppm
Answer: c) 2000–3500 ppm
High-pressure watertube boilers operate with tighter TDS limits to prevent carryover
and scale; 2000–3500 ppm is typical for many industrial units, though specific
limits depend on boiler design and water treatment.
A gauge glass showing a false high water level may be caused by:
a) A blocked steam connection
b) A leaking drain valve
, c) Low boiler pressure
d) Excessive feedwater temperature
Answer: a) A blocked steam connection
If the steam connection to the gauge glass is blocked, steam cannot enter to equalize
pressure, so water is pushed higher in the glass than the actual drum level, giving a
dangerously false reading.
The term "furnace volume heat release rate" is expressed in:
a) kW/m²
b) kJ/kg
c) kW/m³
d) MPa
Answer: c) kW/m³
Furnace volume heat release rate is the amount of heat released per unit volume of
the furnace per unit time, typically in kW/m³, and is a critical design parameter to
avoid slagging and flame impingement.
A boiler safety valve set to pop at 2800 kPa has a blowdown of 4%. At what
pressure will it reseat?
a) 2688 kPa
b) 2720 kPa
c) 2800 kPa
d) 2912 kPa
Answer: a) 2688 kPa
