STATIONARY ENGINEER REVISION EXAM SHEET
QUESTIONS AND SOLUTIONS 2025/2026 GRADED A+
✔✔What is meant by factor of safety? - ✔✔The comparison of the tensile strength to the
actual working stress. The bursting pressure divided by the maximum allowable working
pressure.
✔✔What is the factor of safety for boilers, flywheels, and pipe? - ✔✔New boilers is 4
Pre-owned boilers constructed to ASME code is 5
Flywheels is 4
Pipe is 8
✔✔What is a lap joint? - ✔✔A joint where 2 parts overlap each other
✔✔What is a butt joint? - ✔✔A joint where two parts are connected by placing them
next to each other
✔✔What is a butt strap joint? - ✔✔Is when 2 ends of the plate meet end to end and are
joined by a plate. One plate is a single butt and 2 plates is a double butt.
✔✔is the longitudinal joint the strongest part of the boiler - ✔✔No, it is only the
strongest type of joint, but any joint is the weakest part of a boiler.
✔✔2 boilers are made of the same grade of steel, same thickness of plate, and same
joints. One is 30" in diameter and one is 60" in diameter, which one will stand the
greatest working pressure and demonstrate your answer. - ✔✔30x30x.7854x120psi =
84,823 total pounds of pressure
60x60x.7854x120psi=339,292 total pounds of pressure
The 30" boiler has less pressure on the shell.
✔✔what are tube ligaments? - ✔✔the area between the tube holes on the tube sheet
✔✔What toes of stays are used in the head of a water tube boiler? - ✔✔No stays are
used in the head of a water tube boiler.
✔✔Why is a row of sometimes left out of an H.R.T. Boiler? - ✔✔To improve circulation
which reduces carry over.
✔✔In a fire tube boiler how are the tubes secured in the tube sheet and why? - ✔✔They
are rolled then beaded to prevent heat damage and to keep them from pulling out. For
drainage in the top drums to prevent air pockets in the lower drum.
✔✔Is it necessary to brace or stay a flat surface? - ✔✔Yes, to overcome the force on
heads and flat surfaces where there are no tubes, braces and stays must be provided.
,✔✔Name 3 types of stays? - ✔✔Bolt stay belts, diagonal stays, gusset stays, girder
stays, jaw stays, t stays, j stays, y stays, crow foot stays, palm stays, head brace, screw
vertical bar stays, roof stays, end brace.
✔✔Describe a through stay. - ✔✔They run from one tube sheet to the other, from one
flat surface to another. A rod threads on both ends and is held in place with nuts on the
inside tightened against nuts on the outside of the plates.
✔✔Why are hollow stay bolts used on water legs? - ✔✔A small hole is drilled into the
stay bolt so if it fails a leak will develop and be detected immediately.
✔✔Describe a diagonal stay. - ✔✔A diagonal stay is made of a flat material similar to
the boiler shell and is attached directly to the boiler shell and the head or tube sheet.
✔✔Describe a gusset stay. - ✔✔Consists of boiler plate riveted to the shell and head or
tube sheet by means of angle iron. Used to brace right angles.
✔✔why are hand-holes and man-holes made oval instead of round?
-----
what are the minimum sizes for man-hole and hand-hole openings? - ✔✔So they can
be inserted into and removed from their respective openings in the boiler. Manhole
11x15 or 10x16, hand-hole 2 3/4 x 3 1/2
✔✔What is thermal efficiency? - ✔✔The ratio of heat supplied by the fuel to the heat
absorbed by the boiler.
✔✔What is a good thermal efficiency? - ✔✔85%
✔✔How do you determine boiler capacity? - ✔✔The total heating surface determines
boiler capacity.
✔✔What is boiler heating surface? - ✔✔It has hot gases of combustion on one side and
boiler water in the other. It is measured from the fire-side.
✔✔what is furnace volume?
-----
is furnace volume measured in square feet or cubic feet? - ✔✔Furnace volume is the
space available for complete combustion of the fuel before the products of combustion
enter the heat absorbing sections of the boiler. This varies with the type of fuel used; it
is measured in cubic feet.
,✔✔what is super heated steam? Does its temperature rise? - ✔✔Steam that has been
heated to a higher temp but its pressure remains the same. Yes its temperature does
rise.
✔✔Define flash point - ✔✔The minimum temperature at which a material will give off
ignitable vapors.
✔✔Define ignition point - ✔✔The lowest temperature at which vapors of a substance
will ignite and burn continuously when exposed to an open flame.
✔✔Define pour point - ✔✔It is the lowest temperature at which a liquid will flow
✔✔What is rate of combustion? - ✔✔The rate at which heat is released from a fuel.
✔✔What is combustion? - ✔✔rapid chemical combination of a substance with oxygen,
involving the production of heat and light.
✔✔Does fuel-air mixture have any relationship in figuring the rate of combustion? -
✔✔Yes, when O2 and combustibles are mixed, in definite proportion at an elevated
temp, and given pepper time they will combine completely.
✔✔Define primary air, secondary air, and excess air. - ✔✔Primary air controls the rate
of combustion. Secondary air controls combustion efficiency. Excess air is the amount
above what is required for combustion.
Yes, secondary air is introduced above the fuel bed to burn combustible gases.
✔✔What are the 3 (three) T,s of combustion? - ✔✔Time, temp, turbulence.
✔✔Define PSI, PSIG and PSIA. - ✔✔Pounds per square inch- pressure exerted on a
surface. Pounds per square inch gauge- pressure that is read on a gauge. Pounds per
square inch absolute- gauge reading plus atmospheric pressure.
✔✔could too much secondary air have a bad effect on the efficiency of a boiler? -
✔✔YES, excess secondary air will not enter into the reaction and will pass through the
furnace wasting heat out the stack
✔✔What percent of the air is oxygen by volume? - ✔✔21%
✔✔What percentage of air is oxygen by weight? - ✔✔25%
✔✔Define perfect, complete, and incomplete combustion - ✔✔Perfect combustion-
burning all the fuel using on the theoretical amount of air. Complete combustion-
burning all the fuel using more than the theoretical amount of air. Incomplete
, combustion- when a portion of the fuel remains unburned because of insufficient
amounts of air.
✔✔In a flue gas analysis what is considered a good percent of Co2? - ✔✔12-15% with
20% being ideal
✔✔How is the density of smoke measured? - ✔✔With an opacimeter or Ringleman
chart?
✔✔How do you use a Ringleman chart? - ✔✔The observer glances from the smoke, as
it issues from the stack, to the chart and notes the number of the chart most nearly
corresponding with the shade of the smoke, then records this number with the time of
observation. A clear stack is recorded as No. 0, and 100 percent black smoke as No. 5.
✔✔What grades of smoke are allowed in boiler operations? - ✔✔No darker than grade
1 for more than 5 minutes per hour and no more than 3 times in a 24 hr period.
✔✔What are 7 Heat losses in a boiler? - ✔✔1. Moisture in the air
2. Moisture in the fuel
3. Moisture formed in the burning of hydrogen
4. Incomplete combustion
5. Unburned carbon in the ash
6. Heat carried away in dry flue gasses
7. Radiation and blow downs. 8. Leaks
✔✔What is the heat content of 1 pounds of good coal and 1 pounds of carbon -
✔✔Coal- 13,000-14,000 btu
Carbon- 14,450 btu
✔✔what is an Orsat Apparatus?
-----
where is it used?
-----
why is it used? - ✔✔a flue gas analyzer detecting amounts of CO, CO2 and O2 in flue
gasses
-----
combustion gasses are sampled from the last pass or the breeching
-----
to determine combustion efficiency and excess air
✔✔what is a Fyrite analyzer?
-----
where is it used?
-----
QUESTIONS AND SOLUTIONS 2025/2026 GRADED A+
✔✔What is meant by factor of safety? - ✔✔The comparison of the tensile strength to the
actual working stress. The bursting pressure divided by the maximum allowable working
pressure.
✔✔What is the factor of safety for boilers, flywheels, and pipe? - ✔✔New boilers is 4
Pre-owned boilers constructed to ASME code is 5
Flywheels is 4
Pipe is 8
✔✔What is a lap joint? - ✔✔A joint where 2 parts overlap each other
✔✔What is a butt joint? - ✔✔A joint where two parts are connected by placing them
next to each other
✔✔What is a butt strap joint? - ✔✔Is when 2 ends of the plate meet end to end and are
joined by a plate. One plate is a single butt and 2 plates is a double butt.
✔✔is the longitudinal joint the strongest part of the boiler - ✔✔No, it is only the
strongest type of joint, but any joint is the weakest part of a boiler.
✔✔2 boilers are made of the same grade of steel, same thickness of plate, and same
joints. One is 30" in diameter and one is 60" in diameter, which one will stand the
greatest working pressure and demonstrate your answer. - ✔✔30x30x.7854x120psi =
84,823 total pounds of pressure
60x60x.7854x120psi=339,292 total pounds of pressure
The 30" boiler has less pressure on the shell.
✔✔what are tube ligaments? - ✔✔the area between the tube holes on the tube sheet
✔✔What toes of stays are used in the head of a water tube boiler? - ✔✔No stays are
used in the head of a water tube boiler.
✔✔Why is a row of sometimes left out of an H.R.T. Boiler? - ✔✔To improve circulation
which reduces carry over.
✔✔In a fire tube boiler how are the tubes secured in the tube sheet and why? - ✔✔They
are rolled then beaded to prevent heat damage and to keep them from pulling out. For
drainage in the top drums to prevent air pockets in the lower drum.
✔✔Is it necessary to brace or stay a flat surface? - ✔✔Yes, to overcome the force on
heads and flat surfaces where there are no tubes, braces and stays must be provided.
,✔✔Name 3 types of stays? - ✔✔Bolt stay belts, diagonal stays, gusset stays, girder
stays, jaw stays, t stays, j stays, y stays, crow foot stays, palm stays, head brace, screw
vertical bar stays, roof stays, end brace.
✔✔Describe a through stay. - ✔✔They run from one tube sheet to the other, from one
flat surface to another. A rod threads on both ends and is held in place with nuts on the
inside tightened against nuts on the outside of the plates.
✔✔Why are hollow stay bolts used on water legs? - ✔✔A small hole is drilled into the
stay bolt so if it fails a leak will develop and be detected immediately.
✔✔Describe a diagonal stay. - ✔✔A diagonal stay is made of a flat material similar to
the boiler shell and is attached directly to the boiler shell and the head or tube sheet.
✔✔Describe a gusset stay. - ✔✔Consists of boiler plate riveted to the shell and head or
tube sheet by means of angle iron. Used to brace right angles.
✔✔why are hand-holes and man-holes made oval instead of round?
-----
what are the minimum sizes for man-hole and hand-hole openings? - ✔✔So they can
be inserted into and removed from their respective openings in the boiler. Manhole
11x15 or 10x16, hand-hole 2 3/4 x 3 1/2
✔✔What is thermal efficiency? - ✔✔The ratio of heat supplied by the fuel to the heat
absorbed by the boiler.
✔✔What is a good thermal efficiency? - ✔✔85%
✔✔How do you determine boiler capacity? - ✔✔The total heating surface determines
boiler capacity.
✔✔What is boiler heating surface? - ✔✔It has hot gases of combustion on one side and
boiler water in the other. It is measured from the fire-side.
✔✔what is furnace volume?
-----
is furnace volume measured in square feet or cubic feet? - ✔✔Furnace volume is the
space available for complete combustion of the fuel before the products of combustion
enter the heat absorbing sections of the boiler. This varies with the type of fuel used; it
is measured in cubic feet.
,✔✔what is super heated steam? Does its temperature rise? - ✔✔Steam that has been
heated to a higher temp but its pressure remains the same. Yes its temperature does
rise.
✔✔Define flash point - ✔✔The minimum temperature at which a material will give off
ignitable vapors.
✔✔Define ignition point - ✔✔The lowest temperature at which vapors of a substance
will ignite and burn continuously when exposed to an open flame.
✔✔Define pour point - ✔✔It is the lowest temperature at which a liquid will flow
✔✔What is rate of combustion? - ✔✔The rate at which heat is released from a fuel.
✔✔What is combustion? - ✔✔rapid chemical combination of a substance with oxygen,
involving the production of heat and light.
✔✔Does fuel-air mixture have any relationship in figuring the rate of combustion? -
✔✔Yes, when O2 and combustibles are mixed, in definite proportion at an elevated
temp, and given pepper time they will combine completely.
✔✔Define primary air, secondary air, and excess air. - ✔✔Primary air controls the rate
of combustion. Secondary air controls combustion efficiency. Excess air is the amount
above what is required for combustion.
Yes, secondary air is introduced above the fuel bed to burn combustible gases.
✔✔What are the 3 (three) T,s of combustion? - ✔✔Time, temp, turbulence.
✔✔Define PSI, PSIG and PSIA. - ✔✔Pounds per square inch- pressure exerted on a
surface. Pounds per square inch gauge- pressure that is read on a gauge. Pounds per
square inch absolute- gauge reading plus atmospheric pressure.
✔✔could too much secondary air have a bad effect on the efficiency of a boiler? -
✔✔YES, excess secondary air will not enter into the reaction and will pass through the
furnace wasting heat out the stack
✔✔What percent of the air is oxygen by volume? - ✔✔21%
✔✔What percentage of air is oxygen by weight? - ✔✔25%
✔✔Define perfect, complete, and incomplete combustion - ✔✔Perfect combustion-
burning all the fuel using on the theoretical amount of air. Complete combustion-
burning all the fuel using more than the theoretical amount of air. Incomplete
, combustion- when a portion of the fuel remains unburned because of insufficient
amounts of air.
✔✔In a flue gas analysis what is considered a good percent of Co2? - ✔✔12-15% with
20% being ideal
✔✔How is the density of smoke measured? - ✔✔With an opacimeter or Ringleman
chart?
✔✔How do you use a Ringleman chart? - ✔✔The observer glances from the smoke, as
it issues from the stack, to the chart and notes the number of the chart most nearly
corresponding with the shade of the smoke, then records this number with the time of
observation. A clear stack is recorded as No. 0, and 100 percent black smoke as No. 5.
✔✔What grades of smoke are allowed in boiler operations? - ✔✔No darker than grade
1 for more than 5 minutes per hour and no more than 3 times in a 24 hr period.
✔✔What are 7 Heat losses in a boiler? - ✔✔1. Moisture in the air
2. Moisture in the fuel
3. Moisture formed in the burning of hydrogen
4. Incomplete combustion
5. Unburned carbon in the ash
6. Heat carried away in dry flue gasses
7. Radiation and blow downs. 8. Leaks
✔✔What is the heat content of 1 pounds of good coal and 1 pounds of carbon -
✔✔Coal- 13,000-14,000 btu
Carbon- 14,450 btu
✔✔what is an Orsat Apparatus?
-----
where is it used?
-----
why is it used? - ✔✔a flue gas analyzer detecting amounts of CO, CO2 and O2 in flue
gasses
-----
combustion gasses are sampled from the last pass or the breeching
-----
to determine combustion efficiency and excess air
✔✔what is a Fyrite analyzer?
-----
where is it used?
-----
