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