Stationary Grade 3 Engineering License Exam Questions With 100% Correct Answers 2024, Exams of Advanced Education

Download Stationary Grade 3 Engineering License Exam Questions With 100% Correct Answers 2024 and more Exams Advanced Education in PDF only on Docsity! Stationary Grade 3 Engineering License Exam Questions With 100% Correct Answers 2024 how can you loose your license? - Correct Answer-1) drinking on the job 2) sleeping on the job 3) negligence 4) unsafe work 5) signing a falsified license application for someone 6) failing to renew your license annually what must you do if you change jobs? - Correct Answer-notify city hall if you change jobs, address or retire why should you do rounds? - Correct Answer-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 pg. 1 professoraxe l what is a steam boiler? - Correct Answer-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? - Correct Answer- 1) simple 2) designed to accommodate expansion and contraction 3) adequate steam and water space 4) efficient 5) responsive to demands 6) accessible for cleaning and repairs 7) safe Name and describe 3 types of heat transfer used in boiler operation - Correct Answer-1) RADIANT HEAT - transmitted from hot body to a cold body by means of direct radiation (heat from sun reaches us by radiation) 2) CONDUCTION - physical contact (coffee cup is heated by conduction when hot coffee touches the cup) pg. 2 professoraxe l ----- are HRT Boiler tubes set level or inclined and why? - Correct Answer-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? - Correct Answer-1) Suspended from hangars and supported by overhead beams 2) 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? - Correct Answer- LONGITUDINAL JOINT = seam running the length of the shell pg. 5 professoraxe l and is butt strap construction or fusion welded. it is above the fireline to avoid overheating. ----- CIRCUMFERENTIAL JOINT = lap joint running the circumference of the drum what is the difference between a flue and a tube? - Correct Answer-1) Flue - 4" or more in diameter measured internally 2) Tube - 4" or less in diameter measured externally what is a drypipe and where is it located? - Correct Answer-a steam separator located within the boiler shell and connected to the steam outlet. its upper surface is perforated. steam enters the perforations rapidly changing its direction of flow causing droplets and impurities to separate from the steam before entering the steam outlet. describe a Scotch Marine Boiler? ----- how it is fired - Correct Answer-it is an internally fired self contained horizontal return firetube boiler. ----- pg. 6 professoraxe l it is a cylindrical shell containing the combustion chamber and tubes that are surrounded by water. how is a Stirling Boiler suspended? - Correct Answer-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 - Correct Answer-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? - Correct Answer-1) some tubes are left out 2) the tubes are staggered 3) sometimes, every other row is omitted What is a water tube boiler? ----- pg. 7 professoraxe l 4) can be made portable 5) compact ----- DISADVANTAGES: 1) slow steamers 2) limited in pressure and capacity 3) liable to disastrous explosions because drums and joints are set over the fire 4) inefficient 5) inaccessible for inspection ----- TYPES: 1) H.R.T. 2) locomotive 3) Scotch Marine 4) Vertical fire tube What type stays are used in wet back (Scotch Marine) type boilers? - Correct Answer-stay bolts and through stays. these sometimes will have a telltale drilled in them pg. 10 professoraxe l describe a sectional boiler - Correct Answer-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? - Correct Answer-a super heater is a device used to raise the temperature of steam without raising its pressure. ----- 1) increases efficiency of the boiler 2) delivers dryer steam 3) dryer steam can be transmitted long distances with minimal heat loss 4) dryer steam reduces condensation and erosion what is a radiant type superheater? ----- what is a convection type superheater? ----- pg. 11 professoraxe l what is the third type of superheater? - Correct Answer-A radiant superheater is set over the fire to absorb radiant heat from the furnace by direct radiation ----- 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 what is an economizer? ----- what is a air pre-heater? - Correct Answer-an economizer is a heat exchanger designed to recover waste heat from the products of combustion by pre-heating the feedwater. It's located in the breaching between the boiler and stack. NOTE: there is great economy in heating feedwater. ----- the air pre-heater consists of a series of tubes or plates that have hot gasses on one side and incoming air on the other. heat in the hot gasses leaving the boiler is recovering by the incoming air. ----- pg. 12 professoraxe l what is an alloy? ----- name 5 - Correct Answer-a mixture of two or more metals. ----- 1) brass 2) bronze 3) steel 4) stainless steel 5) cast iron at what pressure is the use of cast iron fittings permitted? - Correct Answer-15 psi. or 250*F. Not to exceed either one what is meant by "Factor of Safety"? - Correct Answer-the bursting pressure divided by the working pressure or the comparison of the tensile strength to the actual working stress what is the Factor of Safety for Boilers, Flywheels and Pipe? - Correct Answer-New boilers is 4 Pre-owned boilers constructed to ASME code is 5 pg. 15 professoraxe l Flywheels is 4 Pipe is 8 what is a lap joint? ----- what is a butt joint? ----- what is a butt-strap joint? - Correct Answer-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 - Correct Answer-NO! it is the strongest type joint, but any joint is the weakest part of a boiler pg. 16 professoraxe l 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 - Correct 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? - Correct Answer-the area between the tube holes on the tube sheet what type stays are used in the heads of water tube boilers? ----- why? - Correct Answer-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 pg. 17 professoraxe l describe a diagonal stay ----- describe a gusset stay ----- where would each be used? - Correct Answer-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? - Correct Answer-so they can be inserted into and removed from their respective openings in the boiler ----- man-hole = 10x16 or 11x15 hand-hole = 2-3/4 x 3-1/2 pg. 20 professoraxe l what is thermal efficiency? ----- what is considered a good percentage? - Correct Answer-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? - Correct Answer-BOILER CAPACITY = total heating surface ----- BOILER HEATING SURFACE = any area that has hot gases on one side - boiler water on the other. MEASURED FROM THE FIRE SIDE. what is furnace volume? ----- pg. 21 professoraxe l is furnace volume measured in square feet or cubic feet? - Correct Answer-FURNACE VOLUME = the space available for complete combustion of the fuel before the products of combustion enter the heat absorbing sections of the boiler. varies with the type of fuel used ----- cubic feet what is superheated steam? ----- does its temperature rise? - Correct Answer-SUPERHEATED STEAM = steam that has been heated to a higher temperature, but its pressure remains the same ----- YES define flash point ----- define ignition point ----- define pour point - Correct Answer-FLASH POINT = the lowest temperature at which vapors of a substance will make a flash pg. 22 professoraxe l 2) temperature 3) turbulence define PSI ----- define PSIG ----- define PSIA - Correct Answer-POUNDS PER SQUARE INCH = pressure exerted on a surface ----- POUNDS PER SQUARE INCH GAUGE = pressure that is read on a gauge ----- POUNDS PER SQUARE INCH ABSOLUTE = gauge readings plus atmospheric pressure could too much secondary air have a bad effect on the efficiency of a boiler? - Correct Answer-YES, excess secondary air will not enter into the reaction and will pass through the furnace wasting heat out the stack what percent of air is oxygen by volume? pg. 25 professoraxe l ----- what percent of air is oxygen by weight? - Correct Answer-% of oxygen in air by volume is 21% ----- % of oxygen in air by weight is 23% define perfect combustion ----- define complete combustion ----- define incomplete combustion - Correct Answer-PERFECT COMBUSTION - burning all the fuel using only the theoretical amount of air ----- COMPLETE COMBUSTION - burning all the fuel using more than the theoretical amount of air ----- INCOMPLETE COMBUSTION - when a portion of the fuel remains unburned because of insufficient amounts of air in a flue gas analysis, what do you consider a good percent of CO2? - Correct Answer-good = 12% to 15% pg. 26 professoraxe l ideal = 20% (mostly unattainable) how is density of smoke measured? ----- how do you use a Ringlemann Chart? - Correct Answer-With an opacimeter or Ringlemann chart. ----- 1) hold at arms length looking through the hole in the chart 2) observers line of sight should be a right angle to the direction of smoke travel 3) observer should be no less than 100ft or no more than 1/4 mile from the stack 4) observer should not look toward bright sunlight 5) the background immediately behind the top of the stack should be free of buildings or other dark objects 6) compare the shade or density of the smoke seen through the hole to the corresponding shade on the chart what grades of smoke are allowed in the City of Omaha boiler operation? - Correct Answer-no darker than grade 1 for more than 5 minutes/hour and no more than 3 times in a 24 hour period pg. 27 professoraxe l ----- where would it be located on a boiler? - Correct Answer- thermometer for measuring temperatures above the range of mercury ----- in the hot gas passages and in the refractory what are tuyeres (tweyars)? - Correct Answer-air-admitting grates on stokers what is a waterback? - Correct Answer-a water wall that is behind the grate on a stoker and its purpose is to cool the wall to prevent clinkers from sticking to the back wall define purging ----- name two types - Correct Answer-purging = the forced removal of combustibles from the firebox. ----- 1) pre-purge = before the pilot is lit 2) post-purge = after the combustion cycle pg. 30 professoraxe l what precautions are needed before a gas, oil or pulverized coal fire is lit? - Correct Answer-purge all the combustibles before you light the pilot. (pilot must be on before the fuel starts) what are pulsations? ----- how would you correct this condition? - Correct Answer- pulsations = when the flame leaves the burner tip and then returns. this may become so severe that the combustion consists of a series of small explosions. ----- how to correct: pulverized coal or oil furnace = the proper air-fuel mixture. gas furnace = increase the draft how do you pipe an oil supply line from the tank to the burner? - Correct Answer-1) oil flows from the storage tank through the suction strainer 2) steam or electric driven pump 3) relief valve pg. 31 professoraxe l 4) steam or electric heater 5) discharge strainer 6) low oil pressure switch 7) firing rate control valve 8) low oil temperature switch 9) safety shut off valve 10) high oil pressure switch 11) on to the burner or tank return (manual isolation valves and bypasses must be installed for all devices so the boiler stays on line during repair) what are some of the difficulties you may encounter when operating an oil fired plant? ----- if you are firing #4 oil and lose oil pressure, what are the first two things you would look for? ----- when would you change a strainer? - Correct Answer- difficulties may include: 1) pump failure 2) plugged strainer pg. 32 professoraxe l #5 - 185*F #6 - 220*F what is a gun type burner? ----- name its parts - Correct Answer-gun type burner = an assembly found on package boilers ----- parts: 1) blower 2) igniter 3) transformer 4) nozzles 5) dampers 6) PRV 7) oil pump 8) metering valve 9) oil or gas solenoid 10) fire eye pg. 35 professoraxe l you are operating on gas and the gas company calls and tells you to go to oil right away. your oil type is #6 and it's ice cold. what will you do and how will you heat the oil to operating temperature so you can fire the boiler? - Correct Answer-1) call your gas company and plead for more time 2) call your boss to get help 3) try to heat the lines with steam hoses or any way you can conceive 4) maybe call your oil company to bring in a tanker with heated oil, etc... 5) use your imagination (think outside the box) 6) DON'T GET CAUGHT IN THIS SITUATION! draw a picture of low pressure gas piping to a burner - Correct Answer-must include: 1) main gas shut off 2) valve 3) a tee to the pilot w/shut-off valve and pilot solenoid 4) manual reset valve 5) gas pressure switch 6) PRV with vent 7) main gas solenoid pg. 36 professoraxe l 8) mixing chamber 9) blower pushing through the venturi 10) into the burner the gas meter for your boiler malfunctions and you have to shut off all gas. how can you keep your boiler on line? - Correct Answer-if you have an alternate fuel, hook up a propane bottle with a regulator to the pilot name 5 electrical devices used on a boiler - Correct Answer-1) oil pumps 2) flame controls 3) flow switch 4) damper motor 5) CCTV cameras what is natural draft? ----- what causes natural draft? - Correct Answer-when the weight of the warm air in the stack is less than the cool air around the stack which causes an upward flow pulling air through the furnace pg. 37 professoraxe l 3) BALANCED DRAFT = the addition of both forced and induced fans, and the boiler operates slightly below atmospheric pressure, about .05 to .10 inches water column. what is a pressurized furnace? ----- why is it not desirable on large boilers? - Correct Answer- PRESSURIZED FURNACE = has a fan placed at the point of air entry to maintain the furnace above atmospheric pressure pushing the products of combustion through the furnace and out the stack. ----- flue gasses can leak into the operating areas and become a health hazard how do you control the dampers on a large fan from a remote location? - Correct Answer-the control panel sends a signal to electric or pneumatic actuators that move the damper linkages if maintenance was done on your boiler, put back in operation, and the stack temperature was higher than normal, pg. 40 professoraxe l what would you look for as the cause? - Correct Answer-water tube boiler = most likely defective or missing baffles fire tube boiler = could be missing turbulators or blocked tubes where are turbulators used and what is their purpose? - Correct Answer-used in the tubes of a fire tube boiler to increase heat transfer to the tubes how often should you test the low water cutoffs and fully describe 3 ways of safely doing this. - Correct Answer-1) at least once a shift furiously blow down the water column and insure that the water returns rapidly and smoothly into the glass 2) EVAPORATION METHOD = once a month done by securing the feed pump and allowing the water to evaporate from the boiler on low fire only. DO THIS WITH SUPERVISION AND REMAIN ALERT DURING THE TEST. 3) SLOW DRAIN METHOD = once a month done by securing the feed pump and slowly blow down the boiler on low fire pg. 41 professoraxe l only. DO THIS WITH SUPERVISION AND REMAIN ALERT DURING THE TEST. how often should you blow down your sight glass? ----- what would you do if the glass broke while the boiler was operating? - Correct Answer-the start of each shift ----- 1) put on safety equipment 2) operate gauge glass shut-off valves 3) use tri-cocks to check water level during the repair 4) open blow-down for the gauge glass 5) remove all the broken glass 6) install the new glass with new washers 7) very slowly, open the top shut-off to warm the glass 8) close the blow-down 9) slowly open the bottom shut-off what would cause a false level in the sight glass? - Correct Answer-1) sight glass closed 2) sediment accumulation pg. 42 professoraxe l with water to normal operating level and measuring the depth of the water to the top row of tubes how high above the top row of tubes in an HRT boiler must the lower gauge cock be set to have a safe amount of water at this point? - Correct Answer-at least 3" above the top row of tubes name 3 appliances that can warn you of low water - Correct Answer-1) water sight glass 2) low water alarm 3) fusible plug if your boiler has only one low water cutoff, what is the ASME code requirement? - Correct Answer-it must be a manual reset. Side note: the City of Omaha requires one to be a manual reset even if you have 2 cutoffs. if there is repair work done on the boiler there must be a manual reset added. what is the purpose of a high fire limit control on a boiler? pg. 45 professoraxe l ----- what is a modulating control? - Correct Answer-it proves that the forced fan damper has fully opened prior to starting the pre-purge period to insure adequate purge air flow. ----- it adjusts the firing rate of the burner to maintain the boiler steam pressure is an automatic shutoff allowed between the boiler and the water column? - Correct Answer-NO, only between the water column and gauge glass what type valves are allowed between the boiler and the water column? - Correct Answer-only O.S. and Y valves or stopcocks which are locked or sealed open. (outside screw & yolk) name 2 types of fusible plugs - Correct Answer-1) fire side 2) water side refers to the side where they are installed pg. 46 professoraxe l what is a bourdon tube? - Correct Answer-a curved tube with an oval cross-section. one end is attached to the frame and pressure connection. the other end is attached to a pointer by linkage and gears. an increase in pressure tends to straighten the tube; its motion is transmitted to the pointer. what is a siphon tube and what is it used for? - Correct Answer-a siphon tube or pigtail loop protects the mechanism of a gauge from live steam. what pressure range should the steam gauge be when used on a boiler? - Correct Answer-it should be a compound gauge at least 1 1/2 times the maximum allowable working pressure where is the steam gauge connected to the boiler? ----- how do you properly mount a steam gauge to a boiler? - Correct Answer-mounted on top of the water column or the the top of the steam drum. ----- gauge is mounted with: 1) a siphon tube 2) a isolation valve pg. 47 professoraxe l how must a safety valve be connected to the boiler? (pic thumb and fingers) - Correct Answer-1) independent of any other steam connection 2) close as possible without any unnecessary piping 3) screwed into the boiler shell or fastened to a flange welded to the shell 4) connected to stand upright 5) vents must be fastened to the building and not connected to the valve!!! at what temperature does a safety valve on a superheater have to be protected with heat resisting materials? - Correct Answer-450*F how do you regulate the blow down of a safety valve? - Correct Answer-the blow down is adjusted by adjusting the blowback ring, the spring or both (about 10%). ONLY TRAINED AND LICENSED PERSONNEL SHOULD ADJUST SAFETY VALVES! how often is it recommended to test your safety valves manually and how often under pressure? - Correct Answer- manually = every 30 days under pressure = annually pg. 50 professoraxe l how is a super heater protected? - Correct Answer-each superheater must have one or more safety valves near their outlet with the pressure set below those on the boiler insuring a constant flow of steam through the superheater a boiler designed to operate at 125 psi is now operating at 15 psi, what changes will be made to the safety valve? - Correct Answer-if change is permanent, install a safety valve with: 1) a larger disk 2) lower pressure rating on an Ashton type safety valve, a screw adjustment is labeled O and S. what do these letters stand for? ----- what adjustments can you make? - Correct Answer-Open & Shut ----- I'm not certified to make adjustments what is a surface blow-off? ----- pg. 51 professoraxe l where is it employed? ----- why is it used? - Correct Answer-removal of oil and contaminants from the surface of boiler water ----- the take-off is located in the top 3-4" of boiler water. ----- It controls the total dissolved solids (TDS) what is a continuous blow down system? ----- where is it installed? - Correct Answer-based on water analysis the surface blow down is metered for a continuous flow. ----- the take-off is located just below the normal operating water level (NOWL) in the steam and water drum how should a continuous blow-down be piped as it leaves the boiler and why? - Correct Answer-piped through: 1) a heat exchanger or flash tank pg. 52 professoraxe l why is it used on blow down lines? - Correct Answer-a circular, tapered plug ground down to fit into the valve body. when open - a hole through the plug aligns with the hole in the valve body. when closed - the holes are out of line. ----- its shearing action cuts through scale and it will not fail open how is a blow down tank piped? ----- how does it work? ----- why isn't any blow down connected directly to the sewer? - Correct Answer-1) blow down enters the tank above the water line and maintained in the tank against a splash guard. 2) vent in the top of the tank to prevent back pressure 3) vent in tank discharge line to prevent siphoning 4) drain valve and manhole in tank for cleaning ----- the discharge line is opposite the inlet, resulting in the cooler water being discharged first. ----- flash steam and hot water directly into the sewer: pg. 55 professoraxe l 1) might injure someone 2) will damage the sewer what is a non-return valve? ----- where is it located? ----- why does it have a drain? - Correct Answer-automatic stop check valve to prevent a back-flow of steam when the boiler pressure falls below that of the header ----- as close to the boiler as possible and between the boiler and the header valve. ----- to remove condensate make a drawing of 3 boilers in battery showing the steam header, valves and piping - Correct Answer-(pic) 3 boilers 3 non-return valves w/condensate drain valves 3 header valves w/condensate drain valves pg. 56 professoraxe l steam header isolation valve/strainer/isolation valve what is a soot blower? ----- how does it work? ----- name 2 types - Correct Answer-a device using jets of steam, compressed air or both to remove the ash and slag from the fire side of the tubes. ----- a revolving blow-arm equipped with properly spaced nozzles that is operated by a chain and wheel while the boiler is in service. ----- 1) manual 2) automatic how do you operate a manual soot-blower? ----- pg. 57 professoraxe l where it is used most often? - Correct Answer-a valve with a wedge shaped gate which is raised or lowered into a passageway. the wedge-shape tightens against the sides of the slot when closed. it offers little resistance to flow when fully open and should not be used to throttle. ----- for isolating devices for repair or to shut off the flow to the boiler what are rising stem valves? ----- what are non-rising stem valves? - Correct Answer-rising = has a stem that rises as the valve opens ----- non-rising = has a stem that stays stationary explain the letters SWP and WOG found on the side of a valve? - Correct Answer-SWP = maximum Steam Working Pressure rating WOG = maximum Water, Oil or Gas pressure the valve may be used for (ie. 140 SWP & 40 WOG) pg. 60 professoraxe l describe a balanced (double seated) feed water valve? ---- why is it used? - Correct Answer-a valve with two disks and two seats. one disk opens with the pressure and one against ---- with forces balanced, it opens easily what is a pressure-reducing valve (PRV)? ---- where is it used? - Correct Answer-PRV automatically reduces high pressure and maintains a lower delivery pressure ---- used for: 1) heating systems 2) cookers 3) city water makeup 4) control air, gas or oil to a boiler what is a check valve? - Correct Answer-valve that allows flow in only one direction pg. 61 professoraxe l name the valves found on a boiler - Correct Answer-1) safety valve 2) water level control valve 3) drain valve 4) fill valve 5) non-return valve 6) plug valve 7) check valve 8) gate valve 9) globe valve 10) butterfly valve 11) maxon valve what is a hydrostatic test? ---- how is it performed? ---- how often should it be done on your boiler? - Correct Answer- a water pressure test used to check the boiler for leaks ---- pg. 62 professoraxe l how do you put a second boiler online with an operating boiler using non-return valves? (8-13 previous question) - Correct Answer-1) if the boiler to come online is hot, open the equalizing line around the header valve to warm the header 2) open header valve drain and non-return valve drain 3) when the header is hot, open header valve and close the drain 4) increase the fire 5) when boiler pressure is 80% of header pressure, unscrew the hand-wheel on the non-return valve and close the drain 6) when boiler pressure equals header pressure, put the controls in automatic what are bags, what causes them and can they be repaired? ---- what are blisters, what causes them and can they be repaired? - Correct Answer-a bag is a bulge in a boiler caused by an overheated area under the scale. small bags can be heated and driven back into place ---- pg. 65 professoraxe l blisters are the separation of layers in the boiler steel caused by a combination of imperfections in the boiler plate and overheating. blisters must be cut away and replaced what is scale? ---- what causes scale? ---- why is it bad for a boiler? - Correct Answer-mineral solids in boiler water being deposited on the heating surfaces ---- it's caused by high TDS (total dissolved solids) and improper boiler water treatment ---- scale forms an insulation layer that retards the flow of heat to the water and causes the metal to become overheated what is corrosion and what causes it? - Correct Answer-the eating away of metal caused by: 1) low alkaline water 2) presence of free oxygen in the water 3) or both pg. 66 professoraxe l what is caustic embrittlement? - Correct Answer-the weakening of boiler steel resulting from inner crystalline cracks caused by a long exposure to a combination of stress and high alkaline water name 3 ways of treating boiler water external of the boiler. ---- name 3 chemical tests done on boiler water. - Correct Answer- 1) distiller 2) water softener 3) reverse osmoses (R.O.) 4) use of chemicals ---- 1) nitrite 2) sulfite 3) chloride 4) phosphate 5) hardness 6) PH 7) conductivity pg. 67 professoraxe l how do you mechanically clean the waterside of boiler tubes? ---- what precautions should be taken? ---- what test should be done after the cleaning? ---- how are boiler tubes cleaned other than with mechanical means? - Correct Answer-fire tubes - a knocker raps the inside of the tube, cracking scale off the outside water tubes - a cutter head rotates inside, cutting and crushing the scale ---- ALWAYS KEEP CUTTER HEAD MOVING! ---- hydrostatic test ---- sometimes acid cleaning by a qualified person is necessary after mechanical cleaning what are pits? pg. 70 professoraxe l ---- what causes pits? ---- how can you determine their depth? - Correct Answer-small hollow spots that could develop into holes ---- oxidation ---- 1) make a plaster cast of the pit and the surrounding plate. after the cast has set, it will show the depth 2) ultra sound 3) eddy current what is a fire crack? ---- is it considered dangerous? ---- what is a tension crack? ---- is it considered dangerous? - Correct Answer-fire crack goes from a rivet hole to the edge of the plate ---- pg. 71 professoraxe l generally not dangerous. ---- tension crack goes from rivet to rivet ---- very dangerous (boiler should be removed from service!!!) how do you wash and prepare a boiler for inspection? ---- how often is your boiler inspected? ---- what is the most important item to check for? - Correct Answer-1) call inspector for appointment 2) reduce T.D.S with blow down so solids won't adhere 3) operate soot blower 4) shut down boiler 5) close, lock and tag all valves 6) turn off, lock and tag electrical switches and breakers 7) allow boiler to cool 8) open vents and drain completely 9) remove all manholes and hand holes pg. 72 professoraxe l frequently check the outer skin and gaskets for visible damage and hot spots how is a leak in the shell detected on a negative pressure furnace? - Correct Answer-1) smoke stick 2) ultrasonic test how many ways are there to patch boiler drums and shells? - Correct Answer-1) bolting 2) riveting 3) welding why are hot water systems more desirable than steam systems for heating buildings? ---- name 2 types of hot water boiler heating systems - Correct Answer-hot water heat is more consistent because water retains its heat as it circulates and steam looses its heat rapidly as it condenses ---- 1) natural circulation 2) forced circulation pg. 75 professoraxe l what is a diverter fitting? - Correct Answer-fitting that meters the water flow from the supply line to the individual heating units name 4 safety devices on a hot water boiler - Correct Answer- 1) temperature-pressure relief valve (same as safety valve for steam) 2) flow proving switch 3) high pressure cutoff switch 4) high temperature aqua-stat 5) flame scanners 6) low water cutoff in hot water heating systems, how often do you test the temperature-pressure (safety) relief valve? ---- how long is the valve held open? - Correct Answer-1) every 30 days of boiler operation 2) after any period of inactivity 3) once a year under pressure ---- pg. 76 professoraxe l the try lever is lifted wide open for a minimum of 5 to 10 seconds or until clean water comes out what devices insure that a pump is running in a hot water system? - Correct Answer-flow switch or differential switch what is an aqua-stat? - Correct Answer-a temperature sensing device. on a heating system it is used to: 1) start and stop the burner 2) open a valve 3) start a fan if you had an expansion (compression) tank on your system, where would it be located and where would the water level be in it? ---- why don't all expansion tanks have sight glasses? - Correct Answer-it will usually be located near the top of the system with the water level mid-way in the tank. the level will go up/down as the temperature and pressure changes. ---- pg. 77 professoraxe l the distance between the lugs and nut on the back side of the "D" slide valve enabling the valve to close slowly and quietly before the pump reverses the stroke what is an air chamber? ---- why is it used? - Correct Answer-located on the intake or discharge of a reciprocating pump ---- relieves the pump from excess strains by absorbing the shock and surges of the liquid being pumped what is a foot valve and its purpose? - Correct Answer-type of check valve located at the bottom end of a suction line to prevent the pump from loosing prime and from running backward when shut down describe a metering pump (power pump) ---- list its 3 features ---- pg. 80 professoraxe l what are its uses in a power plant? - Correct Answer- diaphragm, piston or plunger operated positive displacement pump used for low flow applications ---- features: 1) high head service 2) accuracy of adjustment 3) capable of pumping wide variety of chemicals ---- uses: 1) internal boiler treatment 2) external boiler treatment 3) injecting cooling tower treatment what is the difference between a piston and a plunger? - Correct Answer-a piston has rings installed in grooves of the piston itself & a plunger moves inside stationary rings installed in the grooves of a cylinder describe a rotary pump ---- pg. 81 professoraxe l does a rotary pump work on the same principal as a centrifugal pump? - Correct Answer-a positive displacement pump with grears, vanes, screws, lobes and cams operating in a close fitting casing. They do not use valves in their design, permitting the pump to operate efficiently on both low and high viscosity liquids with a low net postive suction head requirement ---- NO, the rotary pump is a positive displacement pump give 7 advantages of a rotary pump - Correct Answer-1) self priming 2) wide speed ranges 3) low N.P.S.H. requirements 4) capable of high suction lifts 5) capable of high output pressures 6) efficiently handles high and low viscosity liquids 7) efficiently operates on high and low head applications what are the disadvantages of a rotary pump? ---- pg. 82 professoraxe l 8) grease seals 9) thrust bearing 10) bearing end covers 11) packing with: (stuffing boxes) (mechanical seals) 12) "O" rings what are the merits of the centrifugal pump? - Correct Answer-1) few moving parts 2) uniform flow 3) easy to control 4) high capacities 5) dependable 6) long life how do you adjust the flow rate of the centrifugal pump? ---- what would happen if the discharge valve was closed on a centrifugal pump? - Correct Answer-1) throttling the discharge valve ( too much throttling may require the installation of a bypass) 2) changing the speed of the motor. pg. 85 professoraxe l ---- if the valve is closed completely or throttled too much, the pump will slowly overheat what kind of packing is used on centrifugal pumps? ---- name 3 advantages of mechanical seals over packing - Correct Answer-soft metal packing ---- 1) longer life 2) easier to replace 3) no leakage 4) less energy used because of less friction 5) high temperature usage 6) high pressure usage when operating a pump under 200*F, what kind of seals do you use? ---- will there be any leakage and why? - Correct Answer-1) mechanical seals pg. 86 professoraxe l 2) soft metallic packing ---- mechanical seals should not leak * with soft packing, there will be a minimal leakage to cool and lubricate the packing and shaft what problem do you watch for when paralleling two centrifugal pumps? - Correct Answer-make sure the pump capacities remain the same so one pump does not hog the load what would you do if your B.F.W.P. (boiler feed water pump) became steam-bound? - Correct Answer-1) throttle the discharge a little 2) cool the pump with a garden hose 3) maybe install a city water tap to the suction of the pump 4) FIND THE CAUSE is a check valve placed after a pump and why? - Correct Answer-YES * a check valve relieves the pump of start up pg. 87 professoraxe l proper alignment = within .005 inch on a pump, what is: theoretical lift actual lift practical lift ---- what should you limit your suction lift to? - Correct Answer- THEORETICAL LIFT = 34' ACTUAL LIFT = 24' PRACTICAL LIFT = 14' ---- COLD WATER = 10-15' HOT WATER = have to bring water to the pump with a positive head what is the pressure at the base of a pipe 1" in diameter and 1' high? ---- pg. 90 professoraxe l what would the pressure be in a pipe 1" in diameter and 275' high? - Correct Answer-a column of water 1' high exerts a pressure of .433 psi at its base ---- 275 x .433 = 119 psi what is a lantern ring? - Correct Answer-a spacer between the packing rings allowing liquid to be used for: 1) packing 2) cooling 3) prevent the escape of the liquid being pumped why use flexible couplings between the pump and the power source? - Correct Answer-the pump will: 1) run quieter 2) have less wear 3) will be easier to align the flex coupling will: 1) dampen start up shock 2) may act as a shear if the pump seizes. what should the ph in a steam boiler be? pg. 91 professoraxe l ---- what should the ph in a hot water boiler be? ---- what if your condensate return had a ph of 6.5 and what should it be? - Correct Answer-STEAM BOILER PH = 10.5-11.5 ---- HOT WATER BOILER PH = 8-8.5 NEWER HOT WATER BOILER = 10.5 ---- 6.5 ph is corrosive. CONDENSATE PH = 8-8.5 what are the advantages of a feed water heater? - Correct Answer-1) lessen thermoshock damage to the boiler 2) save BTU's 3) can remove free O2 what is a closed feed water heater? ---- advantages? ---- pg. 92 professoraxe l 1) from feed water tank 2) stop valve 3) pump 4) stop valve 5) automatic valve 6) stop valve 7) bypass around automatic valve with glove valve 8) check valve 9) stop valve 10) into boiler name 3 types of pipe used in steam plants ---- what is the temperature and pressure allowed for standard fittings? - Correct Answer-1) schedule 40 (standard) 2) schedule 80 (extra strong) 3) schedule 160 (double extra strong) ---- 450*F & 125 p.s.i. pg. 95 professoraxe l what type of pipe is used for superheated steam? ---- if a boiler operating at 175 psi has a superheater installed, what changes will be made to the cast iron valves and fittings? - Correct Answer-only schedule 160 ---- NO cast iron is allowed on superheated steam. they will be replaced with iron or steel if you installed a steam line that is 100' long, where would you place the anchoring? ---- name 2 ways to take care of expansion in steam lines - Correct Answer-anchor the pipe on each end with an expansion joint in the middle with rollers supporting the pipe ---- 1) expansion bends 2) sliding sleeves 3) corrugated joints note: 100' of steel pipe will grow 5/8" longer per 100*F & copper will grow 3/4-7/8" longer per 100*F pg. 96 professoraxe l name 3 ways to overcome vibration in piping ---- give 3 reasons for insulating pipe - Correct Answer-1) air chambers 2) vibration eliminators 3) support the pipe more securely ---- 1) save fuel and energy 2) prevent sweating 3) SAFETY what are: one-pipe, two-pipe and three-pipe systems and name the pipes in a three-pipe system ---- what is the main disadvantage of a one-pipe system? - Correct Answer-ONE-PIPE SYSTEM = has only one pipe, both steam and condensate go through the same pipe TWO-PIPE SYSTEM = steam is in one pipe and condensate is in another pg. 97 professoraxe l