Exam (elaborations)
3rd Grade Engineer.
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- 3rd Grade Engineer.
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- 3rd Grade Engineer.
Exam of 39 pages for the course 3rd Grade Engineer. at 3rd Grade Engineer. (3rd Grade Engineer.)
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3rd Grade Engineer1. How can you lose your license? - ANS-Drinking on the job, sleeping on the job,
negligence, unsafe work, signing a falsified license application for someone or failing to
renew your license annually.
2. What must you do if you change jobs? - ANS-You must notify city hall if you change
jobs, change address, or retire.
3. Why should you do rounds? - ANS-So you can find and correct problems to prevent
breakdowns. Keeping permanent records will make it easy to forecast most breakdowns
because you will get to know your equipment.
4. What is a steam boiler? - ANS-A steam boiler is a closed vessel PARTLY FILLED
WITH WATER, under pressure, that transforms water to steam with the application of
heat.
5. What are the requirements of a good boiler? - ANS-1) Simple. 2) Designed to
accommodate expansion and contraction. 3) Adequate steam and water space. 4)
Efficent. 5) Responsive to demands. 6) Accessible for cleaning and repair. 7) Safe.
6. Name and describe three types of heat transfer in a boiler operation. -
ANS-RADIANT HEAT is transmitted from a hot body to a cold body by means of direct
radiation. The heat from the sun reaches us by means of radiation.
CONDUCTION HEAT is passed by physical contact. A coffee cup is heated by
conduction when the hot coffee touches the cup.
CONVECTION HEAT is carried along by a moving body such as air or water. Your living
room is heated by warm air from a furnace in another location in your room.
7. What is a combustion chamber? - ANS-The area of the boiler where COMPLETE
burning of the fuel occurs.
8. What is internally fired boiler and name four types. - ANS-Internally fired boilers have
the grates and combustion chamber enclosed within the boiler shell.
Scotch Marine, vertical fire tube, locomotive, and cast iron package boilers.
,9. What is an externally fired boiler and name four types. - ANS-Externally fired boilers
have the setting including the furnace and grates separate and distinct from the shell.
HRT set in brick work, some water tube boilers, Hiene, cast iron boilers set in brickwork
and Sterling.
10. What is the crown sheet and it's purpose? What is the tube sheet and it's purpose? -
ANS-The crown sheet in a vertical fire tube boiler holds the tubes and is thicker
because it is exposed to the fire.
The tube sheet holds the tubes and does not see the fire.
11. What is a water leg on a boiler? - ANS-It is the space between the outer shell and
the furnace shell, containing boiler water. Is absorbs heat that would be wasted and
increases the capacity of the boiler. The surfaces are flat, and must be stayed.
12. Is an H.R.T. boiler set level or inclined and why? Are boiler tubes set level or
inclined and why? - ANS-H.R.T. boilers are inclined 1 to 3 inches front to rear for
drainage and removal or impurities.
Boiler tubes are just inclined with the boiler shell.
13. Name to ways to support and take care of expansion of an H.R.T. boiler? Which way
is best? - ANS-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 from beams is best, that works no hardship on the furnace walls.
14. What is a longitudinal joint? What is a circumferential joint? - ANS-A longitudinal
joint is a seam running the length of the shell and is butt strap constructed or fusion
welded. It is above the fire line to avoid overheating.
A circumferential joint is a lap joint running the circumference of the drum.
15. What is the difference between a flue and a tube? - ANS-A tube is 4" or less
diameter measured externally.
A flue is 4" or more diameter and is measured internally.
16. What is a dry pipe and where is it located? - ANS-The dry pipe is a steam separator
located within the boiler shell and connect to the steam outlet. It's upper surface is
perforated. Steam enters the perforations rapidly changing its direction of flow before
,entering the steam outlet. This causes droplets and impurities to separate from the
steam.
17. Describe a scotch marine boiler and how is it fired? - ANS-It is an internally fired self
contained horizontal return fire tube boiler. It is a cylindrical shell containing the
combustion chamber and tubes that are surrounded by water.
18. How is a Stirling boiler suspended? - ANS-Lugs on the ends of the upper drums rest
on the beams of its structure. The lower (mud) drum is suspended from the tubes and is
free to move by expansion.
19. Describe the circulation of water within the sterling boiler. - ANS-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.
20. What provisions are made for tube removal on water tube boilers? - ANS-Some
tubes are left out. The tubes are staggered. Sometimes every other row is omitted.
21. What is a water tube boiler? What are 5 advantages and disadvantages of a water
tube boiler? - ANS-In a water tube boiler, products of combustion pass around tubes
containing boiler water.
ADVANTAGES: they are rapid steamers, use less water, less chance of explosion, no
flat surfaces and smaller tube size.
DISADVANTAGES: they have elaborate settings, they are field assembled, initial cost
per pound of steam is higher, great number of openings thus more air infiltration and
require more floor space.
FOUR TYPES: D type, A type, O type, B&W, Hiene,
22. What is a fire tube boiler? What are five advantages and disadvantages of a fire
tube boiler? Name 4 types. - ANS-In a fire tube boiler, products of combustion pass
through tubes or flues surrounded by water.
ADVANTAGES: low initial cost, compact, very little setting required, factory assembled
for fast installation, can be made portable.
DISADVANTAGES: liable to disastrous explosions because drums and joints are set
over the fire, inaccessible for inspection, poor circulation, slow steamers, inefficient,
pressure and capacity are limited.
FOUR TYPES: H.R.T., locomotive, scotch marine, vertical fire tube.
, 23. What type of stays are used in a wet back (scotch marine) type boilers? - ANS-Stay
bolts and through stays. These sometimes will have a telltale driller in them.
24. Describe a sectional boiler (cast iron boiler) - ANS-The sectional headers are built
up of vertical sections or units. A sufficient number of sections are clamped together to
form the desired size boiler. These boilers can be erected in an existing building by
carrying them in piece by piece.
25. What is a superheater? What are the advantages of a super heater? - ANS-A
superheater is a device used to raise the temperature of steam without raising its
pressure.
ADVANTAGES: increased efficiency of the boiler, delivering dryer steam, dryer steam
can be transmitted long distances with minimal heat loss, with dryer steam
condensation and erosion are reduced.
26. What is a radiant type super heater? What is a convection type super heater? What
is the third type of super heater? - ANS-A radiant superheater is positioned to absorb
radiant heat from the furnace by direct radiation, it is set over the fire.
A convection superheater is placed in the gas passage of the furnace, usually between
the first and second pass. Little to no radiation will reach this type.
The third type is a combination of radiant and convection.
27. What is an economizer? What is a air pre heater? - ANS-An ECONOMIZER is a
heat exchanger located in the breaching between the boiler and stack designed to
recover waste heat from the products of combustion by pre heating the FEEDWATER.
An AIR PRE-HEATER 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
recovering by the incoming AIR.
Both of these reduce stack temperatures and increase the boiler efficiency.
28. What is a water wall? - ANS-A water wall is a set of tubes containing boiler water set
in the refractory. They absorb heat that would otherwise be lost to the refractory and
they increase the capacity of the boiler.
29. What is A.S.M.E. and it's purpose?
What code info is stamped on the boiler?
Where are the code markings found in a boiler? - ANS-American Society of Mechanical
Engineering has written a set of minimum standards for the safe construction of
pressures vessels.
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