3RD STATIONARY ENGINEER A B TEST QUESTIONS
AND ANSWERS
AB 6. 3 types of heat transfer - Answers :Radiant heat - Transmitted from hot body to a
cold body by means of direct radiation
Co
A 7. What is a combustion chamber? - Answers :The area of the boiler where the
complete burning of fuel occurs.
B 8. What is an internally fired boiler and 4 types - Answers :Internally fired boilers have
the grates and combustion chamber enclosed within the boiler shell.
Scotch Marine
Vertical Fire Tube
Locomotive
Cast Iron Package
B 13. Name 2 ways to support and take care of expansion in a HRT boiler. Which way
is best? - Answers :It can be set on saddles equipped with rollers to permit movement of
the boiler as it expands and contracts. It may also be suspended from hangers and
supported by overhead beams.
Hanging by beams is best, puts no hardship on furnace walls.
B 23. What type of stays are used in a wet back scotch marine boiler. - Answers :Stay
bolts and through stays. These sometimes will have a telltale drilled in them.
B 25. What is a super heater? What are the advantages? - Answers :A bank of tubes
through which only steam passes through without raising pressure.
Advantages: increased efficiency of boilers, delivering drier steam. Drier steam can be
transmitted long distances with minimal heat loss. With drier steam condensation and
corrosion are reduced.
B 27. What is an economize? What is an air preheater? - Answers :Economizer: heat
exchanger located in the breaching between the boiler and stack designed to recover
waste heat from the products of combustion by preheating the feedwater
Air preheater: consists of a series of tubes or plates that have hot gases on one side
and incoming air on the other. heat in the hot gasses leaving the boiler is recovered by
the incoming air.
both reduce stack temperatures and increase boiler efficiency
B 30. Cross section of a 1" bolt - Answers :D x D x .7854
1 x 1 x .7854 = .7854sq"
,B 33. What is meant by "factor of safety" - Answers :The comparison of the tensile
strength to the actual working stress or the bursting pressure divided by the working
pressure.
B 34. What is the factor of safety for boilers, flywheels, and pipes? - Answers :New
Boiler 4
Preowned constructed to ASME standards 5
Flywheel 3
Pipe 8
B 35. What is a lap joint? What is a butt joint? What is a butt strap joint? - Answers :LAP
JOINT = when one plate overlaps the other and is joined
-----
BUTT JOINT = when two ends of the plate meet end to end and are joined
-----
BUTT-STRAP JOINT = when two ends of the plate meet end to end and are joined by a
plate. (one plate is a single butt strap joint / two plates are a double butt strap joint)
B 14. What is a longitudinal Joint?
What is a circumfermential joint? - Answers :A longitudinal joint is a seam running the
length of the shell and it is butt strapped or fusion welded. It is above the fire line to
avoid overheating.
Lap joint running the circumference of the drum.
B 17.Describe a scotch marine boiler and how its fired - Answers :It is an internally fired
self contained horizontal return fire boiler. It is a cylindrical shell containing the
combustion chamber and tubes that are surrounded by water.
B 19. Describe the circulation of water within a Stirling boiler. - Answers :feed water
enters the top rear drum, passes down the rear tubes to the mud drum. steam and
boiler water go up the front and center tubes to the front and center drums.
CIRCULATING TUBES allow boiler water to pass between the drums. what does not go
out as steam, goes back down the rear tubes.
B 39. What type of stays are used in the heads of water tub boilers and why? - Answers
:There are no stays. The head of the boiler drum is shaped with a die, which dishes and
forms them into the shape they would take as a result of the pressure to which they will
be subjected to.
A 40. Why is a row of tubes sometimes left out of an HRT boiler? - Answers :To improve
carryover which will reduce carryover
AB 41. In a fire tube boiler how are tubes secured in a tube sheet and why? In a water
tube? In a water tube boiler why are only some tube ends beaded? - Answers :Fire tube
boiler tubes are rolled and beaded to prevent heat damage, and to keep them from
pulling out.
, Water tube boilers are rolled then flared to keep them from pulling out. Also for drainage
in the upper drum and prevent air pockets in the lower drum.
B 42.Is it necessary to brace or stay a flat surface - Answers :Yes to overcome the force
on heads and flat surfaces. Where there are no tubes or braces, stays must be provided
to prevent bulging of the boilerplate.
Types: "T", "J", "Y" Stays
B 43. Describe a through stay. Why are hollow stay bolts used on water legs? -
Answers :Through stay - Runs from one tube sheet to the other or from one flat surface
to another.
If a stay bolt fails a leak will develop and will be detected at once.
B 44. Describe a diagonal and gusset stay. Where would each be used? - Answers
:Diagonal stay - Made of flat material similar to the boiler shell and is attached directly to
the boiler shell and head or tube sheet.
Gusset stay - Consists of a boiler plate riveted to the shell and head or tube sheet by
means of angle iron. They are more rigid.
Both are used to brace right angle surfaces
A 46. What is thermal efficiency and what is considered a good percent? - Answers :It is
the ratio of heat supplied by the fuel to heat absorbed by the boiler.A good percentage
is 85%, some boilers made today can reach 95%.
A 47. How do you determine boiler capacity and what is boiler heating surfaces? -
Answers :Total heating surface determines the capacity of the boiler.Heating surface is
any surface that has hot gases on one side and boiler water on the other and is
measured from the fire side.
B 49. What is superheated steam. Does its temperature rise"? - Answers :Steam that
has been heated to a higher temperature without raising pressure. Yes its temperature
rises
AB 53. Define primary air, secondary air and excess air. Is secondary air necessary in a
boiler and why? - Answers :Primary air - enters the furnace with fuel and determines
rate of combustion
Secondary air - creates turbulence around fuel to complete the burning process. It is
necessary to combustion.
Excess air - is more than what is needed to complete combustion.
Yes, Secondary air is necessary, it is introduced above the fuel to burn combustible
gases
AB 54. 3 Ts of combustion. - Answers :Time
AND ANSWERS
AB 6. 3 types of heat transfer - Answers :Radiant heat - Transmitted from hot body to a
cold body by means of direct radiation
Co
A 7. What is a combustion chamber? - Answers :The area of the boiler where the
complete burning of fuel occurs.
B 8. What is an internally fired boiler and 4 types - Answers :Internally fired boilers have
the grates and combustion chamber enclosed within the boiler shell.
Scotch Marine
Vertical Fire Tube
Locomotive
Cast Iron Package
B 13. Name 2 ways to support and take care of expansion in a HRT boiler. Which way
is best? - Answers :It can be set on saddles equipped with rollers to permit movement of
the boiler as it expands and contracts. It may also be suspended from hangers and
supported by overhead beams.
Hanging by beams is best, puts no hardship on furnace walls.
B 23. What type of stays are used in a wet back scotch marine boiler. - Answers :Stay
bolts and through stays. These sometimes will have a telltale drilled in them.
B 25. What is a super heater? What are the advantages? - Answers :A bank of tubes
through which only steam passes through without raising pressure.
Advantages: increased efficiency of boilers, delivering drier steam. Drier steam can be
transmitted long distances with minimal heat loss. With drier steam condensation and
corrosion are reduced.
B 27. What is an economize? What is an air preheater? - Answers :Economizer: heat
exchanger located in the breaching between the boiler and stack designed to recover
waste heat from the products of combustion by preheating the feedwater
Air preheater: consists of a series of tubes or plates that have hot gases on one side
and incoming air on the other. heat in the hot gasses leaving the boiler is recovered by
the incoming air.
both reduce stack temperatures and increase boiler efficiency
B 30. Cross section of a 1" bolt - Answers :D x D x .7854
1 x 1 x .7854 = .7854sq"
,B 33. What is meant by "factor of safety" - Answers :The comparison of the tensile
strength to the actual working stress or the bursting pressure divided by the working
pressure.
B 34. What is the factor of safety for boilers, flywheels, and pipes? - Answers :New
Boiler 4
Preowned constructed to ASME standards 5
Flywheel 3
Pipe 8
B 35. What is a lap joint? What is a butt joint? What is a butt strap joint? - Answers :LAP
JOINT = when one plate overlaps the other and is joined
-----
BUTT JOINT = when two ends of the plate meet end to end and are joined
-----
BUTT-STRAP JOINT = when two ends of the plate meet end to end and are joined by a
plate. (one plate is a single butt strap joint / two plates are a double butt strap joint)
B 14. What is a longitudinal Joint?
What is a circumfermential joint? - Answers :A longitudinal joint is a seam running the
length of the shell and it is butt strapped or fusion welded. It is above the fire line to
avoid overheating.
Lap joint running the circumference of the drum.
B 17.Describe a scotch marine boiler and how its fired - Answers :It is an internally fired
self contained horizontal return fire boiler. It is a cylindrical shell containing the
combustion chamber and tubes that are surrounded by water.
B 19. Describe the circulation of water within a Stirling boiler. - Answers :feed water
enters the top rear drum, passes down the rear tubes to the mud drum. steam and
boiler water go up the front and center tubes to the front and center drums.
CIRCULATING TUBES allow boiler water to pass between the drums. what does not go
out as steam, goes back down the rear tubes.
B 39. What type of stays are used in the heads of water tub boilers and why? - Answers
:There are no stays. The head of the boiler drum is shaped with a die, which dishes and
forms them into the shape they would take as a result of the pressure to which they will
be subjected to.
A 40. Why is a row of tubes sometimes left out of an HRT boiler? - Answers :To improve
carryover which will reduce carryover
AB 41. In a fire tube boiler how are tubes secured in a tube sheet and why? In a water
tube? In a water tube boiler why are only some tube ends beaded? - Answers :Fire tube
boiler tubes are rolled and beaded to prevent heat damage, and to keep them from
pulling out.
, Water tube boilers are rolled then flared to keep them from pulling out. Also for drainage
in the upper drum and prevent air pockets in the lower drum.
B 42.Is it necessary to brace or stay a flat surface - Answers :Yes to overcome the force
on heads and flat surfaces. Where there are no tubes or braces, stays must be provided
to prevent bulging of the boilerplate.
Types: "T", "J", "Y" Stays
B 43. Describe a through stay. Why are hollow stay bolts used on water legs? -
Answers :Through stay - Runs from one tube sheet to the other or from one flat surface
to another.
If a stay bolt fails a leak will develop and will be detected at once.
B 44. Describe a diagonal and gusset stay. Where would each be used? - Answers
:Diagonal stay - Made of flat material similar to the boiler shell and is attached directly to
the boiler shell and head or tube sheet.
Gusset stay - Consists of a boiler plate riveted to the shell and head or tube sheet by
means of angle iron. They are more rigid.
Both are used to brace right angle surfaces
A 46. What is thermal efficiency and what is considered a good percent? - Answers :It is
the ratio of heat supplied by the fuel to heat absorbed by the boiler.A good percentage
is 85%, some boilers made today can reach 95%.
A 47. How do you determine boiler capacity and what is boiler heating surfaces? -
Answers :Total heating surface determines the capacity of the boiler.Heating surface is
any surface that has hot gases on one side and boiler water on the other and is
measured from the fire side.
B 49. What is superheated steam. Does its temperature rise"? - Answers :Steam that
has been heated to a higher temperature without raising pressure. Yes its temperature
rises
AB 53. Define primary air, secondary air and excess air. Is secondary air necessary in a
boiler and why? - Answers :Primary air - enters the furnace with fuel and determines
rate of combustion
Secondary air - creates turbulence around fuel to complete the burning process. It is
necessary to combustion.
Excess air - is more than what is needed to complete combustion.
Yes, Secondary air is necessary, it is introduced above the fuel to burn combustible
gases
AB 54. 3 Ts of combustion. - Answers :Time
