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Up Stationary Grade 3 Engineering
License Questions and Answers Already
Passed
how can you loose your license? ✔✔1) drinking on the job
sleeping on the job
negligence
unsafe work
signing a falsified license application for someone
failing to renew your license annually
what must you do if you change jobs? ✔✔notify city hall if you change jobs, address or retire
why should you do rounds? ✔✔Find and correct problems to prevent breakdowns. keeping permanent records will make it easy to forecast most breakdowns because you will get to know equipment
what is a steam boiler? ✔✔closed vessel, PARTIALLY FILLED WITH WATER, under pressure that transforms water to steam with the application of heat.
what are the requirements of a good boiler? ✔✔1) simple
designed to accommodate expansion and contraction
adequate steam and water space
efficient
responsive to demands
accessible for cleaning and repairs
safe
Name and describe 3 types of heat transfer used in boiler operation ✔✔1) RADIANT HEAT - transmitted from hot body to a cold body by means of direct radiation (heat from sun reaches us by radiation)
CONDUCTION - physical contact (coffee cup is heated by conduction when hot coffee touches the cup)
CONVECTION - carried along by a moving part such as air or water (your living room is heated by warm air from your furnace in another location
some watertube
cast iron set in brick
Stirling boiler
Heine boiler
what is a crown sheet and its purpose?
what is a tube sheet and its purpose? ✔✔in a vertical firetube boiler holds the tubes and is thicker because it is exposed to the fire.
holds the tubes and does not see the fire
what is a waterleg on a boiler? ✔✔space between the outer shell and the furnace containing boiler water. it absorbs heat that would be wasted and increases the capacity of the boiler. the surfaces are flat and must be stayed.
is an HRT Boiler set level or inclined and why?
are HRT Boiler tubes set level or inclined and why? ✔✔INCLINED 1-3" front to rear to permit drainage and removal of water impurities
INCLINED with the boiler
Name 2 way to support and take care of expansion of an HRT Boiler
Which way is best? ✔✔1) Suspended from hangars and supported by overhead beams
- Set on saddles equipped with rollers to permit movement of the boiler as it expands and contracts
Suspended from hangars and supported by overhead beams is best because it works no hardship on the furnace walls
what is a longitudinal joint?
what is a circumferential joint? ✔✔LONGITUDINAL JOINT = seam running the length of the shell and is butt strap construction or fusion welded. it is above the fireline to avoid overheating.
how is a Stirling Boiler suspended? ✔✔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.
describe the circulation of water within the Stirling Boiler ✔✔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.
what provisions are made for tube removal on water boilers? ✔✔1) some tubes are left out
the tubes are staggered
sometimes, every other row is omitted
What is a water tube boiler?
list 5 advantages
list 5 disadvantages
name 4 types ✔✔in a water tube boiler, products of combustion pass around tubes containing boiler water
ADVANTAGES:
rapid steamers
use less water
less chance of explosion
no flat surfaces
smaller tube sizes
DISADVANTAGES:
elaborate settings
field assembled
initial cost per pound of steam is higher
greater number of openings thus more air infiltration
require more floor space
TYPES:
can be made portable
compact
DISADVANTAGES:
slow steamers
limited in pressure and capacity
liable to disastrous explosions because drums and joints are set over the fire
inefficient
inaccessible for inspection
TYPES:
H.R.T.
locomotive
Scotch Marine
Vertical fire tube
What type stays are used in wet back (Scotch Marine) type boilers? ✔✔stay bolts and through stays. these sometimes will have a telltale drilled in them
describe a sectional boiler ✔✔the sectional headers are built up of vertical sections or units. a sufficient number of sections are clamped together to form the desired boiler size. these boilers can be erected in an existing building by carrying them in piece by piece
what is a superheater?
what are the advantages of a superheater? ✔✔a super heater is a device used to raise the temperature of steam without raising its pressure.
increases efficiency of the boiler
delivers dryer steam
dryer steam can be transmitted long distances with minimal heat loss
dryer steam reduces condensation and erosion
what is a radiant type superheater?
what is a convection type superheater?
what is a water wall? ✔✔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
what is A.S.M.E. and its purpose?
what code of information is stamped on the boiler?
what is an A.S.M.E. symbol stamp?
where are the code markings found on a boiler? ✔✔American Society of Mechanical Engineers has written a set of minimum standards for the safe construction of pressure vessels.
stamped on the boiler shell or a plate attached to the shell will be:
model and serial numbers
safe working pressure
date of manufacture
horsepower rating
square feet of heating surface
steam generation in pounds per hour
fuel designed for
ASME stamp
the ASME symbol stamp will identify the boiler or accessory type.
fire tube boiler - it may be located by the water column near the front right side
water tube boiler - it will be located next to the manhole on the steam drum
what is the cross section of a 1" bolt? ✔✔DxDx.7854(1/4pi)
1x1x.7854=.7854 sq.in.
show your work and label everything!
what is an alloy?
name 5 ✔✔a mixture of two or more metals.
- brass
what is a butt joint?
what is a butt-strap joint? ✔✔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)
is the longitudinal joint the strongest part of the boiler ✔✔NO! it is the strongest type joint, but any joint is the weakest part of a boiler
two boilers are make of the same grade of steel, same thickness of plate and same type of joints. one is 30" in diameter the other is 60" diameter. which will withstand the greatest pressure and demonstrate your answer ✔✔the 30" boiler-it has less total pressure on the shell.
DxDx.7854(1/4pi)xpsi
30x30x.7854x120 psi = 84,823 lbs. total pressure
60x60x.7854x120 psi = 339,292 lbs. total pressure
show your work on everything!
what are tube ligaments? ✔✔the area between the tube holes on the tube sheet
what type stays are used in the heads of water tube boilers?
why? ✔✔there are no stays
the head of the boiler drum is shaped with a die, which dishes and forms them in to the shape they would take as a result of the pressure to which they will be subjected
why is a row of tubes sometimes left out of an HRT boiler? ✔✔to improve circulation reducing carryover
in a firetube boiler how are the tubes secured in a tube sheet and why?
in a watertube boiler how are the tubes secured in a tube sheet and why?
why are hollow through bolts used on water legs? ✔✔a through stay is a rod threaded on both ends, held in place with nuts on the inside tightened against nuts on the outside of the plates. it runs from one tube sheet or flat surface to the other.
a small hole is drilled into the stay bolt so if it failed a leak will develop and be detected at once
describe a diagonal stay
describe a gusset stay
where would each be used? ✔✔DIAGONAL STAY = made of flat materials similar to the boiler shell and is attached directly to the boiler shell and head or tube sheet
GUSSET STAY = made of boilerplate riveted to the shell and head or tube sheet by means of angle iron. MORE RIGID
both are used to brace right angle surfaces
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
man-hole = 10x16 or 11x
hand-hole = 2-3/4 x 3-1/
what is thermal efficiency?
what is considered a good percentage? ✔✔the ratio of heat absorbed by the water (TO) the heat provided by the fuel
a good percentage is 85%, some boilers made today can reach 95%
how do you determine boiler capacity?
what is boiler heating surface? ✔✔BOILER CAPACITY = total heating surface
