Boiler Maintenance Flashcards
if a boiler tube cannot be removed immediately because of its location in the boiler, and a decision is made to plug the tube, what must be done to the tube after plugging?
puncture the tube to prevent an increase in pressure and the possibility of blowing the plug out of the tube
when laying firebrick with mortar in place, what is the proper procedure for dipping the bricks in mortar?
dip one end of the brick into the mortar, and then with a wiping motion, dip the bottom of the brick
once the mortared firebrick is laid into position, how is it tapped in place?
tap it firmly, both sidewise and backwards, so that it will be forced into position
what is the required size of mortared joints when installing firebrick?
1/16 inch
what type of burner front cracks are caused by stresses resulting from normal expansion and contraction?
radial cracks
what type of burner front cracks eventually results in extensive damage and run approximately parallel to the surface of the Bruner front?
parallel cracks
what is the probable cause of a cartable burner front breaking up after very little use?
too much water was used in mixing the material during installation
the loss of firebrick through cracking and subsequent breaking or crumbling is called what?
spalling
what are the two main causes of refractory deterioration ?
spalling and slagging
what forms slag?
ash and other unburnable materials such as seawater solids that react with brick work?
lowering boiler furnace temperature too rapidly will likely cause what damage to firebrick?
deep fractures
raising the boiler furnace temperature too rapidly will likely cause what damage to firebrick?
firebrick will break at the anchor bolts
what is installed to provide space for the refractories to expand without putting pressure on the linings?
expansion joints
castable should not be mixed until all preparations have been made fro installing the burner front, since the material begins to set at once and must be discarded if it is not used within what time frame?
30 minutes
when using plastic fireclay for burner cone insulation, the plastic is vented at what intervals?
every 2 inches centerline
what is sued to vent plastic fireclay burner fronts?
A 3/16 inch rod tapered to blunt point in the last half inch
when compared to insulating block, firebrick has an insulating value of what?
less than 1/10th that of insulation block
what is the FC-25 fiber fax tamping tax used for?
to repair cracks in deteriorated or failed refractory
anchors used for castable or plastic refractory shall be what type?
pennant type
when working in large areas the refractory anchors should be spaced at what intervals?
every 10 to 12 inches
what is the maximum gap between two sidewall tubes in a D type boiler?
1/4 inch
what is the corrective action for a gap exceeding 1/4 inch on two sidewall tubes?
fill the gap with ceramic fiber or ceramic fiber rope
castable refractory shall be air-cured for how long?
two days or more
lighting fires in boiler with newly installed castable refractory after an air-cure of oil one day is prohibited without approval from whom ?
NAVSEA
a mechanical strain caused by improper operation of the boiler (panting and vibration) will cause what detrimental effect to the furnace wall?
the wall will weaken and become dislocated
how can you visually tell if an expansion joint is closing completely?
if the inside of the expansion joint is light in color, the joint is closing properly. If the inside is dark and discolored, it is not closing properly
what are the major causes of burner front parallel cracking?
improper installation and boiler operating
what is the only way to really determine the condition of a furnace wall?
measure the wall thickness at its thinnest point
the entire furnace deck must be renewed when the firebrick reaches what minimum thickness?
when the thickness is reduced to 1/2 inch for unanchored decks and 3 inches for anchored decks
when treating a boiler with EDTA waterside cleaning chemicals, what is the required percentage of the EDTA solution?
one percent
EDTA used for waterside cleaning must be disposed of in accordance with what publication?
NSTM 503
how often must the boiler be bottom blown, after lit off following EDTA cleaning?
at least every 72 hours and preferably every 48 hours if possible
if the EDTA cleaning is successful, the boiler hours are adjusted in what manner?
the mechanical cleaning hours are zeroed
following EDTA cleaning the boiler is freshly filled and treated with what chemical in accordance with NSTM 220 V2?
disodium phosphate (DSP) only
how often must the boiler be surface blown after lit off following EDTA cleaning?
a 10 percent surface blowdown is conducted every 24 hours
the boiling out procedure for navy boiler is used to remove what type of deposits?
hard deposits
how many pounds of anhydrous trisodium phosphate (TSP) is used per 1000 galloons of feed water when conducting the boiler boiling out procedure?
120 lbs.
how many pounds of sodium metasilicate is required 1000 gallons of feed water when conducting the boiler boiling out procedure?
2 quarts
for an effective boil-out, the chemicals shall be completely dissolved and the solution temperature will be maintained within what temperature range?
300 degrees to 325 degrees F
when conducting boiler boil out, if sodium metasilicate is unavailable, the boil out may be accomplished by using what chemicals?
use trisodium phosphate (TSP), using 200 lbs, per 1000 gallons of feedwater
after completion of boiler boiling out; the boiler must be hydrostatically tested to what pressure?
150 psig
how long must the boiler boiling out procedure last, once the solution reaches the proper temperature?
20 hours
when performing superheater boil out the solution is heated to what temperature?
200 to 210 degrees F
what type of cleaning is required for a newly erected boiler?
boiling out
water washing of boiler firesides shall only be accomplished after approval from whom?
NAVSEA
what is the periodicity for hydrostatically testing burner barrels?
every 1800 to 2000 hours of boiler operation
in what publication can guidance for fitting burner tile can be found?
NSTM 221
when adjacent boiler tubes are warped in such a way that they touch each other, they are defined as what?
married tubes
what causes tube marriages to occur in the boiler?
overheating of tubes or from stresses developing during installation
if 1/4 inch tubes in the main generating bank are married, what corrective action must be taken?
the tube joints are hydrostatically tested at 100 percent boiler steady state pressure and they are satisfactorily pass hydro no corrective action is necessary
to whom must you report all boiler tube failures?
NAVSEA
how can you make a simple gauge for measuring the depth of waterside pits?
by pushing a straight pin or paper clip through a 3x5 inch card.the point of the pin or clip should project beyond the card, at right angles to the card
what are the four classifications of boiler tube damage?
fireside cavities and scars
waterside cavities and scars
tube deformities and fractures
tube deposits
what type of boiler tube damage is indicated by metal loss that occurs in bands or stripes around the circumference of the tube?
circumferential grooving
fireside grooving that causes metal loss and bands around the tube normally occurs at what locations in the boiler?
horizontal tubes such as superheater tubes
what is the most common cause of fireside grooving of boiler tubes?
leakage from tube seats higher up in the bank
what is the term that describes wandering, straight walled, canyon like cavities in the tube metal?
water tracking
both cratering and water tracking usually occur in what area of the boiler?
at the header ends of water wall tubes and division wall tubes
general fireside thinning is defined as what?
a uniform loss of tube metal over a large area on the outside of the tubes
what is the most common cause of the fireside thinning?
soot corrosion
what type of damage occurs when the rate of heat transfer through the tube wall is reduced?
fireside burning
how can tool marks on boiler tubes be easily identified?
they do not resemble corrosion effects in any way
what type of boiler tube rupture resembles a burst bubble; the open lips are uniformly tapered to sharp knifelike edges and there is no evidence of cracking or irregular tearing of the metal?
thin lipped ruptured
what causes thin lipped ruptures?
the flow of steam or wattle was not adequate to absorb the heat to which the tube was exposed
where do thin lipped tube ruptures occur?
economizer tubes, generating tubes and to much lesser extent superheater tubes
a sudden drop in water level or a tube partially blocked by tools or plugs left in the boiler will cause what type of tube damages?
thin lipped ruptures
what type of tube rupture resembles thin lipped ruptures, but their edges are thick and ragged rather than tapered and knifelike?
thick lipped
what type of tube rupture is caused by milder and prolonged overheat?
thick lipped
thick lipped ruptures are the most common type of rupture in which tubes?
superheater tubes
what term is used to describe openings in a tube not associated with tube enlargement?
perforation
what is the most common type of tube perforation?
a pinhole leak
which tubes are normally found to contain thermal cracks?
superheater tubes
heat blisters on boiler tubes are almost always caused by what?
waterside deposits
heat blisters are normally found on what type of boiler tubes?
the fire row of the generating bank
what type of damage causes deformation from semiplastic flow of the tube metal caused by mild overheat?
sagging
what causes warping of boiler tubes?
sudden cooling of the tubes after they have overheated
what is the most common material defect found in the boiler tubes?
tube wall lamination
a string wrapped around an enlarged tube and then laid along a ruler is an improved tool used to measure what?
tube deformity
serious fireside burning is caused by what?
steaming the boiler with a dry tube
when oil contamination is suspected, the boiler must be examined what manner?
the boiler must be examined wet
when the NAVSSES boiler inspector directs you to remove a boiler tube for analysis during a overhaul to determine if the boiler is in need of acid cleaning, which tube do you remove?
screen tube, 2/3 furnace depth
the boiler tubes removed are examined by the activity that removed them and a report of findings and recommended actions are sent to whom?
Type commander, NAVSEA, NAVSSES
what is an exploratory block?
a section of not more Ethan 10 tube side and I must be deep enough to include the tubes in the center row
the need for cutting an exploring block is determined by whom?
engineering officer
where does oxygen pitting mostly occur in boiler tubes?
downcomers, superheaters and at the steam ends of generating tubes
what type of damage causes localized pitting in boiler tubes?
dissolved oxygen
what causes handhold plates of hydrostatic testing, prior to filling the boiler, the handhold nut is tightened to what degree?
1/2 flat beyond fingertight
during hydrostatic testing leaking joints may be tapped to assist in seating the handhold plate up to what pressure?
300 psig
what hydrostatic test pressure is used to check rerolled tube seats for leakage?
100 percent of operating pressure
a new handhold plate is installed in the boiler and was furnished through the navy stock system, what is the hydrostatic test pressure?
125 percent of normal operating pressure
rerolled superheat tubes are hydrostatically tested to what pressure?
125 percent boiler operating pressure
what boiler hydrostatic test pressure is required after replacement of drains, vents, blowdown piping, boiler piping, and welded valve?
125 percent of boiler design pressure
all major welds repairs to boiler headers, drums and renewal or welding to downcomers requires what type of hydrostatic test?
150 percent of boiler design pressure
if a boiler has an unsatisfactorily strength inspection at the five year period, the boiler must be hydrostatically tested to what pressure?
150 percent of boiler design pressure
how often is the boiler inspected for strength and integrity?
every 5 years
what tool is used to cut the old tube flush with the drum or header?
air powered side cutting chisel
what type of packing is usually used on soot blowers?
split ring packing
boiler tubes up to but not including 2 inch rod tubes, must project into drums or headers what distance?
3/16 to 5/16 of an inch
boiler tubes 2 inches od and greater, must project into drums or headers what distance?
5/16 to 7/16 of an inch
when belling boiler tubes up to but not including 2 inches od, what is the required bell?
not less than 1/16* but not to exceed 1/8 inch
when belling boiler tubes larger than 2 inches od what is the required bell?
not less than 1/8” and not more than 3/16 inch
what causes die marks on boiler tubes?
faulty manufacturing of the tube
what is the function of 3/8 inch holes drilled in the front and rear economizer vestibules?
these holes pressurize the vestibules and prevent soot and combustion gases from leaking into the fireroom
how can leaks within the boiler air casing be found?
by using a soapsuds solution and the back of your hand
boiler generating tubes are constructed by what material?
carboon steel
boiler superheater tubes are constructed of what material?
chromium or carbon molybdenum and in some applications stainless steel
how are newly fitted boiler generating tubes properly installed?
by first fitting the tubes in the steam drum and then in the water drum or header
boiler refractory firebrick is designed to withstand what maximum furnace temperature?
3000 degrees F
boiler refractory insulating block is designed to withstand what maximum temperature?
2500 degrees F
boiler refractory insulating block is designed to withstand what minimum temperature?
1500 degrees F
what refractory brick is the innermost layer of the furnace?
firebrick
mortared joints between firebricks must never exceed what clearance?
1/16 inch
when preparing boiler tube ends for tube installation they must be cleaned and polished to what degree?
a distance equal to the thickness of the tube seat plus 2 or 3 inches
what are two types of boiler tube expanders?
roller and ball drift
boiler tube expanders must be operated at what pressure for optimum operation?
100 psi
all boiler tube work and replacement must be recorded on what document?
boiler tube renewal sheet
what is the maximum allowable safety valve lifting pressure tolerance with a steam drum pressure of 31 to 710 psi?
plus or minus 5 psi
what is the maximum allowable safety valve lifting pressure tolerance on boilers with a steam drum pressure of 711 to 1410 psi?
plus or minus 10 psi
what is the maximum allowable safety valve lifting pressure tolerance on boilers with a steam drum pressure of 325 psi or below?
plus or minus 3 psi
what is the maximum permissible boiler safety valve leakage during boiler operation?
a flume not larger than 3 feet emitting from the safety exhaust point
installed boiler safety valve gages are required to be how tight?
hand tight
what effect will boiler safety valves gags have on safety valve operation when they are applies with excessive force?
safety spindle deformation or damage the seating surface
when setting boiler safety valves, what will lowering the nozzle ring on nozzle reaction safety valve cause?
reduces the nozzle effect and decreases safety valve blowdown
when setting boiler safety valves, what will lowering the adjusting ring on a huddling chamber safety valve cause?
decreases blowdown and raises the reseating pressure
what term describes the first escape of steam before a safety valve lifts?
simmer
what term describes a metallic hammering sound or a definite vibratory noise within a safety valve when setting boiler safeties?
chatter
what is the allowable tolerance for a simmering boiler safety valve?
1 1/2 percent of the lifting pressure, provided that it does not occur at boiler operating pressure and provided that is less than the blowdown
what is the corrective action for a chattering safety valve?
disassemble and rebuild the safety valve as required
safety valve settings must never be changed without whose approval?
NAVSEA
at what pressure are boiler safety valve gage placed on the safety valves?
100-200 psi below the lowest safety valve sitting
in accordance with pms procedure what is the maximum number of times you can lift a safety valve unsatisfactorily during the setting of safeties before valve cool down is required?
three successive lifts
boiler safety valve hand easing gear must be checked for proper operations at what periodicity?
every 1800 - 2000 hours of boiler operation
boiler soot blower nozzles are installed in accordance what specifications?
not greater than every third tube if the axis of the element is at right angles to the axis of the tubes or not greater than 3 inches if the axis of the element is parallel to the tubes
what type of packing is usually installed in boiler soot blower?
split ring type
what is the requirement for soot blower head replacement when measured by ultrasonic testing?
when the head thickness has reached 50 percent less than the original thickness specified on the applicable drawing
how are soot blower screw connections prevented from coming loose by vibration or wear?
they must be tack welded in at least three locations around the outside
what is the primary function of the soot blower bearings?
to guide the soot blower
what is the bearing composition of a soot blower bearings?
25% chrome and 20% nickel or 20% chrome and 12% nickel
how many boiler inspection devices (BID) are required per fire room?
one
a fogged mirror on the BID is an indication of what?
unburned fuel vapors within the firebox
