Boiler Operator – National Board Of Boiler And Pressure
Vessel Inspectors Exam Questions And Correct Answers With
Rationales
1.
The primary purpose of a safety valve on a boiler is to:
A. Control water level
B. Control steam temperature
C. Prevent overpressure
D. Reduce fuel consumption
The safety valve releases excess pressure to protect the boiler from explosion.
2.
Boiler water that is too alkaline may cause:
A. Corrosion
B. Foaming and carryover
C. Pitting
D. Scale formation
Excess alkalinity leads to foaming and carryover into steam lines.
3.
The device used to measure steam pressure in a boiler is a:
A. Thermometer
B. Manometer
C. Bourdon gauge
D. Hydrometer
Bourdon tube pressure gauges are standard for measuring steam pressure.
4.
Which boiler fitting is required by code to be placed at the lowest point of the
water space?
A. Pressure gauge
B. Bottom blowdown valve
C. Fusible plug
,D. Water column
The blowdown valve is at the lowest point for removing sludge and sediment.
5.
In a fire-tube boiler, the hot gases:
A. Surround the tubes containing water
B. Pass through tubes surrounded by water
C. Mix directly with water
D. Are vented to the atmosphere
In fire-tube boilers, gases flow inside the tubes and water surrounds them.
6.
A fusible plug is designed to:
A. Relieve excess steam pressure
B. Add chemical treatment
C. Melt and extinguish the fire when water level is low
D. Increase boiler efficiency
Fusible plugs melt when overheated, warning of low water and protecting the
boiler.
7.
Steam traps are primarily used to:
A. Release air and water from steam lines
B. Control boiler pressure
C. Discharge condensate without losing live steam
D. Prevent scaling
Steam traps remove condensate while keeping steam in the system.
8.
What is the purpose of a water column on a boiler?
A. Provide make-up water
B. Reduce water hammer
C. Provide visible water level indication
D. Control fuel input
The water column stabilizes and indicates boiler water level.
, 9.
Priming in a boiler refers to:
A. Initial startup
B. Water carried over with steam
C. Scale formation
D. Pressure relief operation
Priming is water droplets carried into steam lines due to high water level or
impurities.
10.
Scale inside a boiler is dangerous because it:
A. Reduces draft
B. Causes corrosion
C. Reduces heat transfer and overheats metal
D. Increases blowdown frequency
Scale insulates boiler metal, causing overheating and possible failure.
11.
The main cause of boiler corrosion is:
A. High alkalinity
B. Overheating
C. Oxygen in the feedwater
D. Scale deposits
Dissolved oxygen in feedwater attacks boiler metal, leading to pitting corrosion.
12.
When starting up a cold boiler, the operator should:
A. Fire at full rate immediately
B. Warm it up slowly to avoid thermal shock
C. Fill the boiler completely with water
D. Leave all vents closed
Slow heating prevents thermal stresses and cracking of boiler parts.
13.
Vessel Inspectors Exam Questions And Correct Answers With
Rationales
1.
The primary purpose of a safety valve on a boiler is to:
A. Control water level
B. Control steam temperature
C. Prevent overpressure
D. Reduce fuel consumption
The safety valve releases excess pressure to protect the boiler from explosion.
2.
Boiler water that is too alkaline may cause:
A. Corrosion
B. Foaming and carryover
C. Pitting
D. Scale formation
Excess alkalinity leads to foaming and carryover into steam lines.
3.
The device used to measure steam pressure in a boiler is a:
A. Thermometer
B. Manometer
C. Bourdon gauge
D. Hydrometer
Bourdon tube pressure gauges are standard for measuring steam pressure.
4.
Which boiler fitting is required by code to be placed at the lowest point of the
water space?
A. Pressure gauge
B. Bottom blowdown valve
C. Fusible plug
,D. Water column
The blowdown valve is at the lowest point for removing sludge and sediment.
5.
In a fire-tube boiler, the hot gases:
A. Surround the tubes containing water
B. Pass through tubes surrounded by water
C. Mix directly with water
D. Are vented to the atmosphere
In fire-tube boilers, gases flow inside the tubes and water surrounds them.
6.
A fusible plug is designed to:
A. Relieve excess steam pressure
B. Add chemical treatment
C. Melt and extinguish the fire when water level is low
D. Increase boiler efficiency
Fusible plugs melt when overheated, warning of low water and protecting the
boiler.
7.
Steam traps are primarily used to:
A. Release air and water from steam lines
B. Control boiler pressure
C. Discharge condensate without losing live steam
D. Prevent scaling
Steam traps remove condensate while keeping steam in the system.
8.
What is the purpose of a water column on a boiler?
A. Provide make-up water
B. Reduce water hammer
C. Provide visible water level indication
D. Control fuel input
The water column stabilizes and indicates boiler water level.
, 9.
Priming in a boiler refers to:
A. Initial startup
B. Water carried over with steam
C. Scale formation
D. Pressure relief operation
Priming is water droplets carried into steam lines due to high water level or
impurities.
10.
Scale inside a boiler is dangerous because it:
A. Reduces draft
B. Causes corrosion
C. Reduces heat transfer and overheats metal
D. Increases blowdown frequency
Scale insulates boiler metal, causing overheating and possible failure.
11.
The main cause of boiler corrosion is:
A. High alkalinity
B. Overheating
C. Oxygen in the feedwater
D. Scale deposits
Dissolved oxygen in feedwater attacks boiler metal, leading to pitting corrosion.
12.
When starting up a cold boiler, the operator should:
A. Fire at full rate immediately
B. Warm it up slowly to avoid thermal shock
C. Fill the boiler completely with water
D. Leave all vents closed
Slow heating prevents thermal stresses and cracking of boiler parts.
13.
