STEAM BOILERS INTERVIEW QUESTIONS & ANSWERS for Engineers and Utility Operators

1. STEAM BOILERS INTERVIEW QUESTIONS & ANSWERS
Question 1. What Is The Function Of A Boiler?
Answer:
A Boiler supplies dry and saturated steam at the required pressure.
Question 2. Briefly Explain The Boiler Mounting, And Name Its Classifications?
Answer :
A particular apparatus or equipment is placed on the boiler to improve its safety, maintenance
convenience and steam supply, is known as Boiler mounting. Following are the different Boiler
mountings,
o Water level
o Supply valves
o Pressure gauge
o Stop valve
o Feed check valve
o Blow off cock
o Anti-printing pipe
o Fusible plugs etc.
Question 3. What Is A Valve?
Answer :
A valve is used to control the flow of fluid inside the pipeline.
Question 4. Discuss The Function Of Safety, Stop, And Feed Check Valves?
Answer :
o Safety valve. This type of valve is used to keep the boiler safe by controlling the
working pressure in the boiler and resist the blasting due to the high pressure; the
valve is mounted with boiler.
o Stop valve. This type of valve is used to control the flow of steam from the boiler to
the engine.
o Feed Check valve. This type of valve is used to control the supply of feed water to
the boiler. The water level always remains constant when it works.
Question 5. What Is Meant By A Piston And Cylinder?
Answer :
A piston is a cylinder piece of metal. It is moved within a hollow cylinder by the pressure of
fluid (liquid, steam or gas).Pistons are easy fit in the cylinder and piston rings are used to
prevent the leakage in between piston and cylinder.
Question 6. Name The Different Types Of Materials Used To Made Pistons?
Answer :
Pistons are made by different materials such as cast iron, cast steel, aluminium ,bronze, forged
steel, brass etc.
Question 7. What Is A Locomotive Piston?
Answer :
Locomotive pistons are of disc type which are generally made of cast iron or steel. Its piston rings
are made of cast iron and are located by dowels.

2. Question 8. What Is The Difference Between Plunger Piston And Bucket Piston?
Answer :
o Plunger piston is suitable when the fluid pressure is acting on one side of the piston only.
o Bucket piston has one or more valves which permit the fluid to pass one side to the
other.
Question 9. What Is A Buck Piston?
Answer :
It is also known as trunk piston which is open ended and is generally made longer. Cross head or
piston rod is not necessary for it.
Question 10. What Are Piston Rod And Piston Valve Of Steam Engine?
Answer :
Piston rod is fitted inside the piston. The diameter of this rod is inside the piston is reduced to
about 3/4th of its diameter. Piston valve is tightened by a nut and locked out by a pin.
Question 11. Write A Short Note On Steam Engine Piston?
Answer :
Generally box type or hollow type steam engine pistons are used. These are generally made of
cast iron. Box type pistons are cast in one piece with hollow core. This piston is secured by a
nut to the piston rod. To prevent the leakage of the steam two piston rings are provided with
the piston. In the modern reciprocating steam engines the piston made of cast steel and of
conical shape is used. The piston made of cast steel is costly than that of cast iron.
Question 12. What Is A Cross Head Of A Steam Engine?
Answer :
Cross head is used to connect the connecting rod and the piston rod. It is generally made of cast
iron, cast steel or forged steel. The piston rod may be fastened to the cross head either by a screw
or by a cotter pin.
Question 13. Explain About A Crankshaft?
Answer :
The crankshaft converts the rectilinear reciprocating motion into circular motion and vice versa.
When the crankshaft moves through 180 degree, the crank travels over a semicircular path of
the diameter. The crank travels one complete revolution and piston completes two strokes
backwards and forwards, when the crankshaft moves through 360 degree.
Question 14. What Is A Crank?
Answer :
A Crank is a simple lever which receives the thrust of the piston through the connecting rod.
Generally crank disc, eccentric crank, overhung crank, bell crank etc. are used.
Question 15. Name The Different Types Of Packings Used In Steam Engine?
Answer :
o Soft packing. Used for general purposes. It is not suitable for high pressures and
temperatures.
o Metallic packing. It is generally used where high pressures and temperatures exist
because it is more desirable for this purpose.
o Semi-metallic packing. It is used where medium pressures and temperatures exist.

3. Question 16. Write The Procedure For Starting The Power Pump?
Answer :
o Clean the pump.
o Check the correct quantity of the recommended grade of oil to the pump.
o Check the drive rotation.
o Check grease or oil to the coupling if necessary.
o Turn the pump by hand(it should run freely)
o Open the suction, vent, bypass and discharge valves.
o Start the pump.
Question 17. Explain Briefly The Metering Pumps?
Answer :
Generally these types of reciprocating pumps are relatively small and light in weight. Small
reciprocating pumps are fixed on a light structural frame and other pumps have metal base bolted
with the floor. Tank mounted pumps need no foundation but the tank is to be fixed.
Question 18. Name Different Types Of Reciprocating Pumps?
Answer :
Steam pumps, Power pumps, Metering pumps, Axial piston pumps and Sucker rod pumps.
Question 19. Write The Operational Steps Of A Steam Pump?
Answer :
o Make sure that all the suction, discharge, steam and exhaust lines are open.
o Open steam end drain valves.
o Prime by opening air cock on liquid cylinder cap.
o Crack steam valve to warm the pump.
o Open the steam valve until the piston begins to move slowly.
o Close the drain valve and open the steam valve until the pump comes up to the
working speed.
o To stop the pump close the steam valve first and then close exhaust, suction and
discharge valves.
Question 20. What Are The Reasons When Piping Vibrates In Power Pumps?
Answer :
In a power pump the piping vibrates when discharge pipe is undersize or suction pipe is
undersize.
Question 21. Why A Centrifugal Pump Will Not Start?
Answer :
It is due to,
o Impellers locked or not adjusted properly
o Trash in casing
o Faulty motor.
o Too much bearing friction.
Question 22. Explain About Hydraulic Ram?
Answer :
It is an automatic pump. It is generally used to lift a water falling through a small height. i.e,
water falling in large quantity through a small height is lifted to a greater height in small
quantity. The automatic action of the ram takes place due to the inertia force.

4. Question 23. Name Different Types Of Rotary Pumps?
Answer :
External gear pumps, Internal gear pumps, Sanitary type pumps, External screw pumps, Three
screw pumps, Swinging and sliding vane pumps and Flexible rotor pumps.
Question 24. Why A Centrifugal Pump Does Not Deliver Liquid?
Answer :
The centrifugal pump does not deliver liquid due to:
o Wrong rotation
o Pump not primed
o Speed too low.
Question 25. What Are The Causes Of Reduced Capacity Or Pressure In Axial And Radial
Piston Pumps?
Answer :
o Clogged or leaking suction.
o Oil is too thick.
o Relief valve troubles.
o Liquid lever is too low.
Question 26. Name Different Types Centrifugal Pumps?
Answer :
Multistage pumps, Process type pumps, Chemical process pumps, Canned motor pumps, Paper
stroke pumps and Deepwell turbine pumps.
Question 27. What Is The Main Reason Of Steam Pump Breakdown?
Answer :
Steam pump stops due to valve trouble. i.e, incorrectly set or worn steam valves may stop the
steam pump.
Question 28. Why A Steam Pump Does Not Discharge?
Answer :
It is due to ,
o Suction air bound
o Suction lift too high
o Obstruction in suction line
o Pump not primed.
Question 29. What Is A I.c Engine?
Answer :
It is a heat engine in which the chemical energy of combustion is released inside the engine
cylinder, thus fuel is fired inside the cylinder. It is more useful as compared to the other engines.
Question 30. Write A Short Note About Spark Plug?
Answer :
The spark plug is the main part of the engine. In the I.C engine having spark ignition, the fuel
–air mixture in the cylinder is ignited through the medium of spark ignition electrical system
which occurs at the electrode of the spark plug. The charge induced into the cylinder during its
cycle’s first process. In the spark ignition engine , the gases compressed in the cylinder during
the compression stroke consists of the fuel and air.

5. Question 31. What Is Connecting Rod Of An I,c Engine?
Answer :
The connecting rod is made of forged steel. Its big end is connected to the crank and small is
connected to the piston. The brass in the big end is die cast and lined with white metal. Separate
connecting rods are used for petrol, diesel and gas engines.
Question 32. Explain About A Carburetor?
Answer :
The control and regulation of the mixture strength can be obtained automatically in the engine
by carburetor. In its operation air from the air cleaner enters the main air passage and passes
through the choke. Fuel from the float chamber enters and flows to the fuel jet. The depression
in the choke causes petrol to flow from the jet where atomization of the fuel takes place. The
mixture of the fuel and air passing into the induction system. The suction piston will rise and
fall under the influence of engine suction which combined with the position of throttle control.
Question 33. What Is The Purpose Of Fuel Injector Pump In The Engine?
Answer :
In the modern oil engines the injection of the fuel into the cylinder is accomplished not by an
air blast but by means of injection pump. These pumps are built strongly and accurately. For
preventing after drip and consequent burning of the fuel left on the spray nozzle tips, its pressure
must drop as quickly and accurately as it rises.
Question 34. What Do You Meant By A Petrol Engine?
Answer :
It is a spark ignition engine. The induced charge in its cylinder consists of a mixture of air and
fuel. The fuel used in it can be vaporized readily. The petrol engine can operated on the
compression-ignition principle.
Question 35. What Is A Two Stroke Petrol Engine?
Answer :
It is a simple engine having Piston, Connecting rod and Crankshaft. Valves and valve actuating
accessories are eliminated because intake and exhaust gases accomplished by the opening in
the cylinder wall which are controlled by the piston. This type of engine has a small horse
power output.
Question 36. What Is A Diesel Engine?
Answer :
It is a engine in which a low grade oil is used. The fuel is ignited by the heat of air in this engine.
Question 37. Write A Short Note About Two Stroke Diesel Engine?
Answer :
It is an engine in which two strokes of the piston are required to complete one cycle to operate
the engine. The functions of both the strokes are as under:
o First stroke compress the air in the engine to ignite the fuel oil.
o Second stroke is the power stroke which is produced by the burning gases.

6. Question 38. Explain About A Gas Engine?
Answer :
It is a slow speed engine in which gaseous fuel is used. Variety of gas fuels are used such as
town gas, natural gas, blast furnace gas, oil gas, coke oven gas etc. This type of engines are
generally of stationary type but portable gas engines are also available.
Question 39. What Is The Difference Between Single Acting And Double Acting Engines?
Answer :
Single acting Engine. It is a engine in which the pressure producing power stroke is exerted
only on one side of the piston. It works on both the two stroke and four stroke engines.
Double acting Engine. It is a engine in which the pressure producing power stroke is exerted
first on one side of the piston and then on the other end. It makes each stroke of the piston a
power stroke.
Question 40. What Is Meant By Four Stroke Diesel Engine?
Answer :
It is an engine in which four strokes of the piston are required to complete one cycle to operate
the engine. The functions of each stroke is as under:
o First stroke draws air to the cylinder.
o Second stroke compresses the air.
o Third stroke is the power stroke which is produced by the burning gases.
o Fourth stroke drives out the burnt gases.
Question 41. Define Static Electricity?
Answer :
When a glass rod is rubbed with a silk cloth, it becomes positive charge and when a ebonite rod
is rubbed with a woolen cloth, it becomes a negative charge. The change produced in glass or
ebonite rod is known as Static electricity. There is no movement of electrons in this electricity.
Question 42. What Is Current Electricity?
Answer :
The electrons move and flow along the conductor in this electricity. If direction of flow
electrons is always the same, it is known as Direct Current (D.C). If the direction of flow of
electrons is changed constantly, it is known as Alternative Current (A.C).
Question 43. Define Volt?
Answer :
Volt is the force which causes an electron flow of one ampere through a resistance of one ohm.
Question 44. What Are The Advantages Of A.c Over D.c?
Answer :
o A.C is produced much more as compared to D.C.
o An alternative voltage can be increased to a desired limit by a transformer while D.C
can not be increased.
o A.C is less expensive than that of D.C.
o A.C induction motors are more useful for constant speed as compared to D.C motors.
o A.C motors require less maintenance as compared to D.C motors.
o A.C generators can be made in large size which can run at high speed also than that
of D.C generators.

7. Question 45. Define Ampere?
Answer :
It is the amount of electron flow in the current . In one ampere 6.28*10/18 electrons has a given
point in the conductor within a period of one second.
Question 46. Write A Short Note About Fuse?
Answer :
A fuse is a small piece of wire which is normally used in the circuit. It protects against the bad
effects of short circuiting. When a current in the circuit rises above its desired limit, the fuse
will be heated and melt which causes the circuit “Open” and saves the components and
appliances from the possible damage.
Question 47. What Do You Meant By A Short Circuit?
Answer :
It has not resistor. It causes a high current flow which may heat up the wire. It may cause fire
and damage the electrical appliances in the circuit.
Question 48. What Are The Effects Of Electric Current?
Answer :
o Heating effect. When a current flows in a wire and generators heat like filament lamp,
electric heater, furnace etc. is called electric effect.
o Chemical Effect. When electricity passes through a chemical solution , it can make
chemical like cells, batteries, electroplating etc. it is called chemical effect.
o Magnetic effect. When a current flows in a coil ,it makes a magnetic field like bell,
motor, generator, transformer, tape recorder etc. called magnetic effect.
Question 49. What Is The Difference Between Conductors And Insulators?
Answer :
o Conductors. When a material allows electrons to flow through it known as
conductors. Eg. Copper, aluminum, iron ,tin, gold .
o Insulators. The materials which prevent the flow of electrons are known as insulators.
Eg: Rubber ,asbestos ,plastics, mica.
Question 50. What Are The Advantages Of D.c?
Answer :
o It is suitable for traction work.
o It is suitable for charging batteries.
o It is suitable for variable speed motors used in printing machines.
o It is useful lamps used in projectors.

8. BOILER OPERATOR INTERVIEW QUESTIONS & ANSWERS
Question 1. Do You Know In Flight, How Many Attempts Will The Auto start Perform?
Answer :
The auto start will make continuous start attempts until the engine either starts or the pilot aborts
the start attempt. FCOM 1 70.20.7
Question 2. Tell Me Who Is A Power Plant Operator?
Answer :
A power plant operator is a person who operates a power plant. He has got to be good at the
technical skills of using the power plant and must be equally talented in distributing the work
to the other workers who are working with the power plant.
Question 3. Tell Me When Is The Auto-relight Function Activated?
Answer :
When ever an engine is at or below idle with the fuel control switch in RUN. FCOM 1 70.20.8
Question 4. Tell Me What Can You Do To Drive The Blades Of The Turbine Faster And
Preventing The Damage Of The Blades?
Answer :
Steam should be heated to the temperature it is before making it to enter the turbine because
superheated steam produces a lot of energy and also prevents the blades from rusting or damaging.
Question 5. Tell Me What Things Are Missing From A Natural Gas Power Plant To A Coal
Power Plant?
Answer :
CHP & stock yard, crushers, coal conveyors, wet or dry ash disposal, ash slurry disposal units, ash
pond, LDO HFO oil elevations.
Question 6. Explain What Are The Primary Engine Parameters Displayed On Eicas?
Answer :
EPR, N1 and EGT. FCOM 1 70.20.1
Question 7. Explain When Is A Cross bleed Start Indication Displayed Next To The N3
Indication?
Answer :
If the airspeed is below that recommended for a wind milling start. FCOM 1 70.20.7
Question 8. Do You Know What Are The Secondary Engine Parameters?
Answer :
N2, N3, fuel flow, oil pressure, oil temperature, oil quantity and engine vibration. FCOM 1 70.20.1
Question 9. Do You Know How Many Ignitors Are Used For In Flight Starting?
Answer :
Dual ignitors are always used for in flight starts. FCOM 1 70.20.8

9. Question 10. Tell Me Have You Ever Come Across A Situation When The Plant Went Into
Some Technical Issues, How Did You Manage That?
Answer :
Technical issues are very common in a plant, give an example from your past experience where
you successfully managed to overcome a technical issue.
Question 11. Tell Me After The Production Of Electricity, Why Do We Increase The
Voltage Before Sending It To The Grid?
Answer :
To avoid the transmission losses.
Question 12. Tell Me Which Eicas Message Indicates That Actual Thrust Is Significantly
Less Than The Commanded Thrust?
Answer :
ENG THRUST (L or R). FCOM 1 70.20.16
Question 13. Tell Me What Is The Amount Of Energy Out Of The Total Energy Produced
That Is Taken Away By The Boiler Feed Pump?
Answer :
A boiler feed pump takes away one third part of the energy generated by the power plant.
Question 14. A Grate, In A Boiler, Is A Place In The Combustion Chamber Upon Which
Fuel (wood Or Coal) Is Burnt.
Answer :
True
Question 15. Explain What Will You Do When Your Timed Schedule Or Jobs Assigned To
The Plant Fail To Meet Due To Some Unforeseen Forecast Conditions?
Answer :
This happens generally on every other day in this profession, but the key is not to stay back but
move on. I will take some preventive measures to avoid loss of resources.
Question 16. In Water Tube Boilers Are?
Answer :
water passes through the tubes which are surrounded by flames and hot gases
Question 17. Explain And Convince Me That You Can Adapt To A Wide Variety Of People,
Situations And Environments?
Answer:
Switching from oil to propane.
Question 18. Do You Know And Can You Comment Why Some Cooling Towers Are 300
Feet Tall And Others Are Like 30x30 Cubicle On Top Of A Building?
Answer :
It depends on the type of plant and the application the tower has to deal with it.
Question 19. Tell Me Which Rotor Vibration Is Most Likely To Cause Tactile Vibration?
Answer :
N1. FCOM 1 70.2016

10. Question 20. Explain Why Is A Block Of Coal Crushed Into Powder Before Burn?
Answer :
A block of coal takes a lot of time to burn and give out the energy, but the powdered coal burns
uniformly faster and since it is in its powdered form the entire coal burns and there is no waste
of coal which leads in achieving greater calorific value.
Question 21. Do You Know What Is Lock Out Tag Out?
Answer :
It is a procedure that is used for the protection of the workers and the equipment’s during the
maintenance or repair of the power plant.
Question 22. Explain When Will The Engine Fail Message Appear On The Pfd?
Answer :
If actual thrust is less than commanded thrust during takeoff with airspeed between 65kts and
V1-6kts. FCOM 1 70.20.16
Question 23. Tell Me What Do You Feel Is An Acceptable Work Attendance Record?
Answer :
Safety driven and self directed, I can and do work with minimal supervision and always put my
plant and co- workers safety above all else.
Question 24. The Object Of Producing Draught In A Boiler Is?
Answer :
1. to provide an adequate supply of air for the fuel combustion
2. to exhaust the gases of combustion from the combustion chamber
3. to discharge the gases of combustion to the atmosphere through the chimney
Question 25. Explain What Is The Difference Between An Induced Draft And Forced
Draft?
Answer :
Forced draft installed to force the air inside the plant while the induced draft fetches and pulls
the air inside the air.
Question 26. Explain How Important Is Safety To You?
Answer :
Safety in this profession is very important for every worker working inside the plant. A small
mistake can lead to a big hazard and hence every minor chance of a mistake should be taken
seriously.
Question 27. Explain The Abilities You Have In Order To Work With Us As A Boiler
Operator?
Answer :
I'm familiar with the boiler operation, I was trained to fix and install boiler. I am a good trouble
shooter and a good operator.