CLASS 5 BOILER MAIN EXAM TEST 2025/2026 QUESTIONS
WITH ANSWERS GRADED A+
✔✔Dry Pipe - ✔✔Pipe running along the top of steam space in which slots are cut in top
or side for purpose of admitting only dry steam to line. One has blank ending, other is
connected to steam outlet. Drain holes drilled on bottom.
✔✔What is the point of a dry pipe - ✔✔to aid in removal of moisture from steam as it
leaves the steam drum
✔✔what kind of stamp must a company posses to to weld on boilers - ✔✔R stamp
✔✔ASME - ✔✔American Society of Mechanical Engineers
✔✔According to ASME, how many valves must be on the main steam line of a high
pressure steam boiler? - ✔✔2. Jurisdiction ends after second.
✔✔Longitudinal joint - ✔✔Joint subject to greatest stress
✔✔Bottom Blowdown Valve - ✔✔removes sludge and sediment, drains boiler for
maintenance, located on bottom of mud drum in WTB or bottom of boiler on Firetube
✔✔Breeching - ✔✔exhaust pipe between boiler and chimney
✔✔Hot Water SUPPLY Boiler - ✔✔water heater for domestic use
✔✔Safety *Relief* Valve - ✔✔Prevents overpressure of water boiler. Spring loaded pop
type, discharge capacity rated in Btu/hr. Must be hand tested quarterly in all boilers.
Minimum size 3/4. Can be T&P or Pressure only
✔✔How often does a Safety Relief Valve need to be tested - ✔✔Quarterly
✔✔Minimum size for safety relief valve - ✔✔3/4
✔✔Superheater - ✔✔increases steam temp but not pressure. allows for use of steam
longer. Increases efficiency. exposes steam to combustion gases so it won't condense
after first stage of steam turbine. Located in radiant outlet area of boiler
✔✔Dry firing - ✔✔flow of steam is necessary to keep superheater from overheating and
getting damaged
✔✔Reheater - ✔✔increases steam temp for latter sections of steam turbine
✔✔Economizer - ✔✔preheats feed water
, ✔✔pre heater - ✔✔pre heats combustion air. Important in solid fuel burners.
✔✔Why does heat transfer from hot to cold? - ✔✔Due to difference in temperature or
density
✔✔Law of conservation of mass - ✔✔Cannot be created or destroyed, only altered
✔✔PSIG - ✔✔Gauge pressure
✔✔PSIA - ✔✔Absolute pressure= gauge + 1 atm
✔✔1 Atm. - ✔✔14.73 psia
✔✔Celsius to Fahrenheit - ✔✔C= (F-32) / 1.8
✔✔Fahrenheit to Celsius - ✔✔F= (C *1.8) +32
✔✔Pyrometer - ✔✔Can be thermal electric or optical. Measures stack gas temperatures
in breeching
✔✔British Thermal Unit - ✔✔amt. of energy required to increase 1 lb of water by 1
degree Fahrenheit
✔✔Sensible heat - ✔✔Heat you can sense, feel, measure
✔✔Latent heat - ✔✔causes physical change in state or phase but no change in
temperature
✔✔How many Btu of latent heat does it take to change 1 lb water to steam? - ✔✔970.4
Btu of latent heat
✔✔Specific heat - ✔✔amount of heat energy required to increase the temperature of 1
lb of substance by 1 degree fahrenheit
✔✔3 types of heat transfer - ✔✔Conduction, convection, radiation
✔✔Conduction - ✔✔Direct contact, no mix
✔✔Convection - ✔✔mixing of 2 or more fluids to become 1
✔✔radiation - ✔✔electrical energy waves. Heats objects not air
WITH ANSWERS GRADED A+
✔✔Dry Pipe - ✔✔Pipe running along the top of steam space in which slots are cut in top
or side for purpose of admitting only dry steam to line. One has blank ending, other is
connected to steam outlet. Drain holes drilled on bottom.
✔✔What is the point of a dry pipe - ✔✔to aid in removal of moisture from steam as it
leaves the steam drum
✔✔what kind of stamp must a company posses to to weld on boilers - ✔✔R stamp
✔✔ASME - ✔✔American Society of Mechanical Engineers
✔✔According to ASME, how many valves must be on the main steam line of a high
pressure steam boiler? - ✔✔2. Jurisdiction ends after second.
✔✔Longitudinal joint - ✔✔Joint subject to greatest stress
✔✔Bottom Blowdown Valve - ✔✔removes sludge and sediment, drains boiler for
maintenance, located on bottom of mud drum in WTB or bottom of boiler on Firetube
✔✔Breeching - ✔✔exhaust pipe between boiler and chimney
✔✔Hot Water SUPPLY Boiler - ✔✔water heater for domestic use
✔✔Safety *Relief* Valve - ✔✔Prevents overpressure of water boiler. Spring loaded pop
type, discharge capacity rated in Btu/hr. Must be hand tested quarterly in all boilers.
Minimum size 3/4. Can be T&P or Pressure only
✔✔How often does a Safety Relief Valve need to be tested - ✔✔Quarterly
✔✔Minimum size for safety relief valve - ✔✔3/4
✔✔Superheater - ✔✔increases steam temp but not pressure. allows for use of steam
longer. Increases efficiency. exposes steam to combustion gases so it won't condense
after first stage of steam turbine. Located in radiant outlet area of boiler
✔✔Dry firing - ✔✔flow of steam is necessary to keep superheater from overheating and
getting damaged
✔✔Reheater - ✔✔increases steam temp for latter sections of steam turbine
✔✔Economizer - ✔✔preheats feed water
, ✔✔pre heater - ✔✔pre heats combustion air. Important in solid fuel burners.
✔✔Why does heat transfer from hot to cold? - ✔✔Due to difference in temperature or
density
✔✔Law of conservation of mass - ✔✔Cannot be created or destroyed, only altered
✔✔PSIG - ✔✔Gauge pressure
✔✔PSIA - ✔✔Absolute pressure= gauge + 1 atm
✔✔1 Atm. - ✔✔14.73 psia
✔✔Celsius to Fahrenheit - ✔✔C= (F-32) / 1.8
✔✔Fahrenheit to Celsius - ✔✔F= (C *1.8) +32
✔✔Pyrometer - ✔✔Can be thermal electric or optical. Measures stack gas temperatures
in breeching
✔✔British Thermal Unit - ✔✔amt. of energy required to increase 1 lb of water by 1
degree Fahrenheit
✔✔Sensible heat - ✔✔Heat you can sense, feel, measure
✔✔Latent heat - ✔✔causes physical change in state or phase but no change in
temperature
✔✔How many Btu of latent heat does it take to change 1 lb water to steam? - ✔✔970.4
Btu of latent heat
✔✔Specific heat - ✔✔amount of heat energy required to increase the temperature of 1
lb of substance by 1 degree fahrenheit
✔✔3 types of heat transfer - ✔✔Conduction, convection, radiation
✔✔Conduction - ✔✔Direct contact, no mix
✔✔Convection - ✔✔mixing of 2 or more fluids to become 1
✔✔radiation - ✔✔electrical energy waves. Heats objects not air
