SOUTH TYNESIDECOLLEGE FACULTY OF MARINE AND MECHANICAL ENGII\EERING CLASS 4 EXAMINATION OUESTIONS l.
Explain what you know about 66M"Notices. Merchant shipping notices, or "M" notices as they arecommonlycalled,occupya specialposition. are advisory notices which do not have a force in law, but thosewhich give advice on safety matter regarded as authoritative documents by courseof inquiry into shippingcasualtiesand as such woulr considered extremely persuasivein a legal sense. There are now three tlpes of notice issuedby the MCA 1. MGN ( Marine Guidance Notes ) Blue Provide advice and guidance on safety and pollution matters. 2. MIN ( Marine Information Notices ) - Green Provide information intended for a more limited audienceor of shortterm duration. 3. MSN ( Marine Shipping Notice ) White Will contain mandatory information relating to the legal requirementsetout in related statutory instruments. There is no legal requirements to carry Marine GuidanceNotes andMarine information Notes on UK registeredvessels. It is a legal requirement to carry Merchant ShippingNotices.
2.
Explain what you know about " Code of Safe Working Practices". Accidents are usually the result of carelessness, mistakes,lack of thoughtor careand often result in Consideration must be given on how to avoid accidentshencethe " Codeof Safe Working practice Examples include the wearing of working clotheschosenforthe job with its hazardsin mind. They fit fairly closely with no loose flaps, strapsor raggedpockets. Ciothing shouldcover as much as the as possible and a stout pair of shoesshould be worn, with steeltoecaps.Neck chains,finger rings ar wristwatches should not be worn, particularly in the vicinity of rotatingmachinery. Where particula hazards are present appropriate protection such as gogglesor ear muffi, shouldbe worn. When overhauling machinery or equipment it must be effectively isolatedfrom all sourcesof power may involve unplugging from an electrical circuit, the removal of fusesor the securing open of circu breakers. . Suction and discharge valves of pumps shouldbe securelyclosedand the pump casing rel pressure. Special care should be taken with steamoperatedor steamusingequipmetrt to "ngye no F build up occurs. When lifting components during overhaul, screw in eyeboltsshouldbe usedwhere possible. These : be fully entered up to the collar and the thread of the eyebolt shouldbe in good condition. Lifting w should be in good condition without broken strandsor sharpedges. Before any work is done on the main engine, the turning gear shouldbe engagedand a warning notic posted at the control position. Lubricating oil in the working areashouldbe cleaned up and where necessary suitable staging erected. The turning gearshould be madeinoperativeif nofrequired durir overhaul- Where it is used, care must be taken to ensureall personnelareclear before it is used. Overhead working, boiler operation. Entry into enclosedspacesare otherexampleswhere special car procedures have to be rigidly followed never taking short cuts.
3'
What portable extinguishers would you expectto find in an engine room and what colo used?
The outercontainercontainssodiumbicarbonate powder. A capsuleof carbon dioxide gasis locatr beneatha plungermechanismin thecentralcap. bn depressing the plunger the carbondioxide gas the powderup a dischargetubeandout if the discharge-nozzle. The dry powderextinguisherconbeusedon all classes offire but it hasno cooling effecl It is t, locatednear electricalequipmentin the mochinerytpori and elsewhereon the ship. Foam- Red 5% Cream/Buff--Chemical The main containeris filled with sodiumbicarbonate solutionand a long inner polyhene container with aluminiumsulphate.Theinnercontaineris sealedby a capheld in place Uy r plunger. When plungeris unlockedby turningit , thecapis released.Theextinguisheris then inverted-forthe two to mix- Carbondioxideis producedby thereactionwhichpressurisesthe container and forcesout t foam. Foam- Red 5% Cream/Buff--Mechanical The outercontainerin this caseis filled with water.The centralcontainerholds a carbondioxidech a foam solution.A plungermechanism with a safetyguardis locatedabovethe central container. Whenthe plungeris depressed thecarbondioxideis releasedandthe foam solution and the watern: arethen forcedout througha specialnozzlewhichcreatesthe mechanicalfoam. This extinguisher I internalpipeandis operatedin theuprightposition. Foam extinguishersare usedon classB fires and witl be located in the vicinity ofjtammabte tiqa C.O2- Red 5% Black A very strongcontaineris usedto storeliquid carbondioxideunderpressure. A central tubeprovidr outerpassage for the carbondioxidewhichis releasedeitherby a plunger bursting a disc or a valve operatedby a trigger. The liquid changes to a gasasit leavesthe ixtinguisher *d pursesthroughth swivelpipeor hoseto a discharge horn. Carbondioxideextinguishersaremaintyusedon ClassB and Cfires and wig befound in the ma space,particularly near electricalequipmenl The carbon dioxitle extinguisher i not permitted it accommodationsince,in a conJinedspaceit is lethal. - Red CFC Extinguishers
5%Green
Soda- Acid Red The containerof this extinguisherholdsa sodiumbicarbonatesolution. The screw-on cap containsr plungermechanism coveredby a safetyguard.Belowtheplungeris a glassphial containingsulphur Whenthe plungeris strucktheglassphialis brokenandthe acidand sodium bicarbonatemix. The resultingchemicalreactionproduces carbondioxidegaswhichpressurisesthe spaceabovethe liquir forcing it out throughthe internalpipeto the nozzle. This extinguisheris usedfor classAfires and will befound in the accommodation ereas. 4.
what type of fire extinguisherwouldbe usedon a fire in:-? (a) Galley (b) Accommodation(c) ControlRoomor Radio Room (d) Electrical Switchboard (e) Pump Room (a) Galley- CO2andDry Powder (b) Accommodation- SodaAcid Extinguisher ( seebelowfor description) (c) control Roomor RadioRoom- coz or Dry powder (d) ElectricalSwitchboard- COZor Dry powder (e) Pumproom- Foam,COzor Dry powder
5.
what are the main causesof serious engine room fires ? oil leaks. Fuel, hydraulicor lubricating oil onto hot surfaces. Smoking, burningor welding. Rags and combustibledebrisallowed to build up in the bilge's
6.
\ilhat immediateaction must be taken if a fire becomes serious enough to have to evacuate all personnel from the engineroom and what precautions must be taken before re-entering? Flood the machineryspacewith whatever fixed fire installation is fitted. Say CO2. Before flooding get everybodyout. - do a head count. Where possibleall personnelmust be made aware of the decision to flood the machinery spacewith The spacemust thenbe completely sealed4gainst the entry and exit of air and all oil suiplies isolatr tank valves. When all thesemattershave beenattendedtoothe COz can be admitted and if the srurounding bulkl hold to containthe ftre , it will quickly go out. Cooling of the boundary bulkheads should continue outside the spacewhile flooding is taking place. When the extinguished fir. has been left long enou cool down the spacecan be re-entered. This should be done from the tunnel, if there is one, oi frolowest point from the seatof the fire. Engineers wearing breathing apparatusmay now enter, taki water sprayhoseswith them to cool down any hot surfaces. Coolingand smoke dispersalare the fir priorities, to providean atmospherein which others can operate andgradually bringthe machinery s back into service. Where a machineryspacefire involves electrical equipment then only dry powder or Co2extinguisl be used until the equipmentis isolated.
7.
What pumps on board ship can be used to supply water to the fire main ? Fire pump.- usuallytwo or three fitted Fire and bilge pump. General servicepump. Emergencyfire pump.
8.
Is there an emergencyfire pump ? If the answer is y€s, where is it fitted and how is it tested? External to the machineryspace.-Run on a weekly basis. Some pumps maybe fitted in the steeringcompartrnent.
9.
Define what you would considerto be an enclosed space where the internal atmosphere may br frequently hazardousto personnelwho may enter. Duct Keel, doublebottomtanks,cofferdams,boilers, CO2 rooms, pumprooms. Bow thruster compartmentsshouldbe teated with caution if ventilation fans have not been running. Fore peak anr peak tanks shouldalsobe well ventilated and tested before entry.
10.
Describe the procedurewhich should be adopted:(a) Before anyoneis allowed to enter an enclosed space. (b) While anyoneis working inside a closed space. (i) Ventilation for at least24 fus. (ii) Test of atrnosphere by a chemist or Chief Officer for Oxygen and Hydrocarbon content.Zlyo o> (iii) Tank entry permit and tally board for personnel to enter tank. (iv) Breathingapparatusat tank entrance,lifeline and portable lights(air), communication, ild tallier people enteringalongwith ELSA sets. (b) While anyoneis working in the tank there must be a man at the entrance at all times with a mezu communicationbetweenhim and the person(s) in the tank and the Bridge.
ll.
what types of pumps are suitable for useas bilge pumps? Positivedisplacement.- small volumesfor usewifi ows centrifugal with priming pump - Largevolumedischarge.
12.
Give reasonswhy a bilge pump may not be able to removewater from bilges. state typical suction and delivery pressures. Blockedstrum box. ( very high nuru.r* on the gauge) Hole in suction line. ( zero or very low vacuumon the gauge ) Primingpump not functioning if working in serieswith centrifugalpump.
13.
Explain what is the emergency bilge suction( injection).Why is it necessarT and how is it bn into operation? A bilge injection valve is fitted to the end of a branchline connectingwith themainseawatersuct The bilge injection valve is always of the screwdownnon-returntype. This valveenablesthe larg seawatercooling pump to be usedas a bilge pumpin an emergency.To bring thebilgeinjectionv useduringan emergency, the bilge injectionvalveis openearutyand the seasuctioi valveis full; After it is establishedthat the seawatir pumpis capableof loweringthewater levelin theengine seawatersuction may be openedslowly. This shouldbe donein stales sothatthetanktopsareno dry,asthis would causethe seawaterpump to losesuction. Careshould betakento ensuethatthe oftensituatedon the outlet from the main condenser doesnot dischargenearanyelectricalequipmr NB. Seawater pumps are not usually self priming,if of the centrifugiltype.
14.
lhat is the purpose of the oily water separator? To allow the bilges to pumped overboardwith an oil contentof not more thanl5ppm. ReadMARPOL regulations.
15.
Explain in detait the procedure for testingthe steeringgear beforeleaving port. check for oil leaks and any loose linkageson th. steeringgear. check for correctoil level and test low level alarm. Run oneunit at a time, 30 degs-to 35 degs.in 28 secsat full power. where onlyonemainunit is fi anx' unit, the auxiliaty unit must go from 20 degs.to 20 degs.In 60 secs. g at knotsor half speed. Testthe communicationlink betweenthe Bridgeandthe Stee.irrgcompartment.
16.
What is the duty of the engine room crane? To enablelarge and hearryengine componentsto be manoeuwedaround theEngineroomin a safe manner.
17.
Detail checkswhich should be carried out beforeusingthe crane and possible hazardsif not functioning correctly. CheckSWL is not exceeded. Checkthat the direction indicators on the controlscorrespondto the actual movement ^^!of ' v^thecrane. Checkthatthe limit switchesare working. Checkthat the brake is operational. Checkthat all personnelinvolved understandthe signalsto be usedin anyrepairor overhaul.
18.
Give the correct procedure for starting an air compressor. (a) Checkthe oil level (b) Checkthe cooling water. (c) Ensurethat the interstage drains are open. (d) Checkthat all the correct valves *" ol"n fully to the air receiver andthatthereis sufficientca1 availablein the air receiver.. (e) If a manualunloaderis fitted ensurethat it is open.( machine mustbestartedin theunloaded position). (D Whenthe machineis up to speed,closethe unloaderand the interstage drains.
19.
What is the purpose of fitting a bursting disc into the air compressorcasing? A bursting disc' or sometimes a water jacket relief valve are fittedto prevent a build-up of pressur€ a cooler tube fail allo*ing high pressureair to enterthe cooling *ut.i space.
20.
Describe the procedure required to connect in parallel one dieselor steamdriven alternator already on the switchboard with another alternator. Three-phase alternators ilranged for parallel operationrequire a considerableamount of instrume This will include arnmeters, wattmeter, voltmeter, frequencymeteranda synchronising device. M these instruments will use transformers to reducethe actual valuestakento the instrument. This al enables switching, for instance, between phasesor an incoming machineand the bus-bar, so that o: instnrment can display one of a number of values. The watfinetermeasuresthe power being used ir circuit' which' because of the power factor aspectof alternatingcurrentload. will be less thL the p: the volts and amps. Reverse power protection is provided to alternatorssincereversecurrentprotection cannot be used. Alternatively various trips may be provided in the event of the prime mover failure to ensure that th alternator does not act as a motor. The operation of paralleling two alternatorsrequiresthe voltage to be equaland in phase. The alter current output of any machine is always changing,so for two machinesto operatetogether their vol must be changing at the same rate or frequencyand be reachingtheir ma,rimum( or Ly other value together They are then said to be' in phase'. Use is nowadaysmade of a synchroscope when paralleling two machines. The synchroscope has two windings which are connectedoneto eachside of th. p*utt"l switch. A pointer is free to rotate and is moved by the magneticeffect of the two windings. When the two v supplies are in phase the pointer is stationaryin the 12 o'clock position. If the pJinter is rotating tht frequency difference exists and the dial is marked for clockwise rotationFAST and anti-clockwise r sl-ow, the reference being to the incoming machinefrequency. To parallel an incoming machine to a running machinetherefore,it is necessaryto ensure firstly tha voltages are equal. Voltmeters are provided for this purpose. Secondlythe frequencies must ULUro into phase. In practice the synchroscopeusually *orr.r slowty in the fast direction and the parallelir switch is closed as the pointer reachesthe l1 o'clock position. This resultsin the incoming machinr immediately accepting a small amount of load. A set of three lamps may also be provided to enablesynchronising. The sequence method of lamp connection has a key latnp connectedacrossone phasewith the two otherlamps connected over the two phases. If the frequencies of the machinesare different. The lampswill brighten and darken in rotation, depending upon the incoming frequencybeing FAST or SLOW. The correct moment for synchronising is when the key larnp is dark and the other two are equallybright.
21.
What is the purpose of having a synchroscopeand why must it not be allowed to run continuo To ensure alternators to be connectedto bus-barsare at th; correctfrequency. Not to be allowed to rtrrt continuously becausethey are not continuousiyratedand will burn out.
22.
Explain how an emergency alternator starts and supplies power in the event of a blackout. (a) Double pole switch trips on lose of power and on tripping makescontact with emergencyswitch supplying power to emergencygeneratorstartermotor. (b) A low voltage coil, typically 24v, is connectedto the main switchboard. This coil is normally energised and corutected to a normally open contactoron the air startsystemfor the alternator. r the main power fails the coil de-energises,thus completingthe air startsystemand starting the alternator. once the alternator has startedthe air will shut off. When the machine is up to speedand has the correct cyclesand volts, the auto synchroniser will the breaker and put it on the board, (emergencyboard) to supply the essentialservices.
23.
How can a blackout be simulated to test the operation of the emergency alternator? Turn auto synch to offposition to preventthe emergencygenerator tying to put itself on the board starts. Shut power offto startingcoil, this will de-energisecoil and machine will start.
24.
How often should an electric motor be cleaned? Unless there are any specific problemsevery 5 years. Use of vibration monitors are helpful in high bearing problems and thermal trips in the windings can give prior warning of impending problems.
25.
How would you overhaul an electric motor that has been flooded with sea water? Strip down and wash with distilled water,then dry out, if possible in an oven, then check meggar r Should be minimum of I megohm. Heatinglamps can also be used. On completion coat with ,. gor quality electrical varnish.
26.
Explain how to check the insulation resistanceof the motor using a ..Meggerrr. Corurectthe Meggar betweeneachphasein nrrn and the motor casing, after good contact has been : removing paint etc. Resistanceshouldbe I megohm.
27.
Outline the dangers to pensonnelwho may have to enter a battery room to check the conditio: batteries on charge. Hydrogen fumes in poorly ventilatedbatteryrooms which contain lead-acid batteries can be fatal. lr naked flames and dangerfrom sulphuricacid burns. Safety gear must be worn including full face v No smoking as there could be dangerof explosion.
28.
What is the temperature inside low pressureevaporators and why is the water produced suitr drinking? Drinking water can only be madefrom salt water in evaporatorsif it is boiled above 75 degs. C. Mr the low pressureplants operateat tempsranging from 4d degs C. to 60 degs C. and are therefore ur for making drinking water. Other problems to look out for areadditivesusedin diesel engine cooling systems and inhibitors u' water systemsto prevent fouling by marinegrowth.The evaporator should not be used within 12 mi. land
29.
what are the reasonsfor using the main engine turning gear? (a) To ensurethat the engineis warmedup evinly dissipalittg *y thermal stresses in materials ever therefore the enginecan be loadedmore quickty. (b) For warming through with the indicator cocks open to ensure there is no water leakage in the cy (c) To be engagedif any major overhaulof the engine is taking place. (d) For taking deflections.
30.
Why is tappet clearancenecessaryand what effect would insufficient or excessive clearance h: engine operation? Tappet clearancesare necessaryto allow for the thermal expansion of the valve spindle length at wo temperatures'and to ensurethat positive closing of the valve continues as it wears or seats d*irrg ,r, Clearancesshould normally be setwhile the engineis cold and the czrm follower is offthe cam peak wear of the valve gearwill tend to increaseclearances. Excessive tappet clearanceswill causethe valve to open late and close early in the cycle and will rec ma'ximum lift- It will also causenoise,and eventually damage,from the impact of working surfaces Insufficient clearancewill causethe valve to open early and close late with increased marimum lift. extreme cases'it may preventthe valve from closing completely as it expands or beds in. This in tul causehot gasesto blow past valve faces,causing.ruln burning and low compression.
31.
Describe how to prepare the main enginefrom cold to ready to start to manoeuvring includi: that require to be carried out. (1) Before a large diesel engineis startedit must be warmed through bv circulating hot water thror jackets etc' This will enablethe various engine parts to expand in relation to one another and a engine load to be increasedsoonerratherthan later. The lubricating oil should also be heatedand circulated around the bearings etc., and the pisto: cooled. The various return pipes on both the water and oil systemsshould be checked to ensureno blo and the return temperatuesshouldbe monitored. (2) The various supply tanks, filters, valvesand drains are all to be checked and opened or closed i required (3) All control equipment,alarmsetc. shouldbe examined for correct operation. (4) The indicator cocks should be openand the turning gear engaged and started to ensurethat ther water presentin the cylinders.If any water issuesfurth.r investigation can be ca:ried out to asc
Tnecause. (5) All oil levelsshouldbechecked, i.e.sump,turbochargers, governorsetc. (6) The fuel oil systemcanbelinedup andcirculatedwith hot fuel. (7) Any scavenge blowersif manuallyoperated, shouldbe started. (8) Manuallyoperatethe cylinderlubri.utorr. (9) The turninggearshouldberemovedandtheengineblown over on air before closing the indica cocks. (10) The engineis nowavailablefor standby. , l
32.
Why shouldthe cylinderindicatorcocksbeleft openuntil the engine has first beenturned ov, starting air? To ensurethatno waterissuesfromthecockswhich would indicate a leak from the liner, cylinder head,pistoncooling,turbobroweror injectorcooling.
33.
Describethe routineinspectionyouwould carry out beforetaking over the watch on a manne engineroom arrangement.. Checkthe firnnelemissions.Whitesmoke,blacksmoke,steamor sparks. Checksteeringgearandfridgeflats. Enterthe engineroomfrom thetop. Do not usethe lift. Checkcoolingwaterheadertank. check main enginecoolingwaterreturnsandtemperatures. check pistoncoolingwaterreturnsandtemperatures. Listenfor anyunusualnoises. Checkturbochargeroil levels Checkobservation tankfor signsof oil. Checkmist detector. Checkconditionof bilges. Checkpurifier flat andconditionof thefuel oil tanks.i.e. full, empty, temperature.Drain of water. Entercontrol.oop: check log bookandnoteanyirregularities. Confirm the conditionof the electricalsupplyequipmint. How many alternators on load,) amountof J ----on the board.Earthfaults.Standby machines. Readany curent standingorders. The duty engineershouldthen 1nfo* theengineertakingoverthe watch of any abnormal operating conditionswhichhaveoccured duringthewatch.Any oidrr, from the Bridge, recordedin the log br shouldbe pointedout.Any repairsshouldbereportedtogetherwith information on any machinerytt beendismantled'Thepresence of anyothermembersoflhip's staff in the engineroom e. g. Dayvor shouldbe reported.
34.
Give the various operating pressures and temperatures of an engine you are familiar wi
Scavenge air temperatureScavenge air pressure L.O.pressure L.O.temperafire JacketC.W.pressure
40/45 degs.C 1.0 Bar 2.0 Bar 45 degs.C 3.0 Bar
JacketC.W. temperatue -
65 degs. C
- 5/6Bar F.O.Pressure F.O. Temperahre 125 Degs.C Cylinderoil pressure- 40 bar
35.
What factors must be present for an explosion to occur in the diesel engine crankcase? For a crankcaseexplosion to occur, oil mist must be present in the crankcase,and a hot spot must develop,perhapsfrom bearing wear or stuffing box rub etc. The hot spot then ignites the oil mist ca an explosion. ( Seehandout on crankcase explosions or Note 22 CLass4 )
36.
What devicemay be used to detect and warn of dangerous conditions within the crankcase? A Gravineroil mist detector is used to detect and warn of dangerouslevels of oil mist in the crankca The detectorconsistsof two tubes, fitted at one end of each is a photo electric cell, the other end is a lens to allow the passageof light through the tube of the P.E. cell. Light comesfrom a singlebulb a reflectedto eachtube by a mirror. One tube is sealed and contains clean air and is termedthe referer tube. The other tube is called the measuring tube and is used to pass samplesthrough it. Samplesa drawn from the crankcaseusing a fan drawing through a rotary valve. If a large amountof mist is dr into the measuringtube, less light can penetrate the tube to the P.E. cell, so therewill be a differencr output from each sample and depending on the amount of difference will activatean alarm. In the er an alarm,the load of the engine should be reduced immediately by slowing to Dead Slow Aheadand soonas possiblethe engine should be stopped and the turning gear engaged. Openthe indicator coc turn the engineto prevent seizure. Allow engine to cool to normal operatingconditionsby observin returntemperatures.Whensafe BUT NOT BEFORE 20 MINS the crankcasedoors can be openedar crankcaseinspected. A visual inspection from outside the crankcaseshould be madefor signsof wl metal or excessiveoil leakagefrom bearings or anything which might indicate a problem. If nothing obviousthe lubricating oil pump can be stopped and a more detailed inspectioncarried out.
37.
What immediate action should be taken in the event of a warning being given? Reducepower manually if crankcase mist detector does not do so automatically. Receivepermission the bridgeto stop the engine. Allow to cool down before inspecting the crankcasefor signsof the hc (Seenote23 Class4 notes)
38.
What factors must be present for a scavenge air manifold fire to start? Dirry scavengeair trunking. lncorrectamount of cylinder lubricating oil. Defectivefuel valve and bad combustion. lncorrectfuel valve timing. Worn piston rings and liner. Chokedexhaust. Defectivestuffing box. ( Seeclass 4 notes page 20 )
39.
How would you becomeaware that a scayenge fire had started? Erratic enginespeed. High exhausttemperatures. Smell of burning paint. Turbochargersurge. Smokefrom funnel. Rise in J.W. temperafire of affected unit.
40.
How would you deal with a scavenge fire? In the event of a scavenge fire the bridge must be informed, as should the C/E, that the enginehasto reducedto D.S. Ahead immediately. Increasecylinder lubrication to all units by increasing the mechanicallubricator flow to mar
41.
What factors must be present for an explosion to occur within the starting air pipelinesand wl limits the effect of an explosion? Heat. Usually in the form of a leaking air start valve. Fuel. In the form of lubricating oil coating the internal sr:rfacesof the air start lines. Air. Devicesfor limiting the effects of explosion are.(l) Flametraps.(2) Bursting discs. (3) Reliel
42.
What is meant by the supercharging of a diesel engine and how is this achieved? Superchargingis a means of supplying air to a cylinder at a greaterpressurethan atmospheric.This , doneon earlier designsby means of scavengepumps, roots blowers,underpiston scavengesystemst Disadvantageswith earlier systems were that they used up to 7% of enginepower to drive the mecha to boost the airpressure. With the introduction of the turbochargerthe above componentswere phas out, although some installations combine both.
43.
Describethe operating cycles of a two-stroke and four-stroke diesel engine. 4-stroke Air inlet valve opens - piston moves down cylinder drawing in air - air inlet valveclosesa pistonmovesup cylinder compressing trapped air - just beforepiston getsto TDC fuel is injectedexpansionof gas forces piston back down cylinder where at BDC exhaustvalve opens- piston rloVer up cylinder forcing out exhaust gases ready for the cycle to start over again. One completecycle takr degs. 2 - stroke Air enters cylinder through scavengeports, exhaustvalve may still be openon turbocharl engines- trappedair is compressed - just before TDC fuel is injected- combustiontakesplaceand expansionof the gas forces the piston down the cylinder where the exhaustvalve opensto expel the exhaustgeNes- the piston uncovers the scavengeports to allow the fresh chargeair into the cylinder . exhaustvalve closesand the cycle starts over again. One completecycle takes360 degs. Note. The higher the boost pressure the longer the exhaustvalve overlap.
44.
Explain the function of a turbo-charger. To boost scavengeair pressure to a pressure greaterthan atmosphericwith no loss of enginepower. Volutecasing-Filter-Inducer-Impeller-Difhrser-Rotor-TurbineWheel-NozzleRing--Labyrin Gland - Bearings - Oil Pumps/Thrower Rings.
4s' 3:#hiil|]ilHll#Hve
acvlinder linerrromararge two-stroke srowspeed
Remove alr connectionsfrom the cyrinder head. Remove the cylinderhead. Remove the pistonrod nut. Disconnectstuffing box from diaphragm. Grind off the carbg'lbuild up on the liner beforelifting thepiston. Tap out rhepiton lifting bolf holes. Lift the piston from the cylinder Remove the lubricatorquilrsfrom the riner. Fit the liner lifting gear. Removethe liner. 46'
Explain how scaleforms on the heating surfacesof boilers. If the feedwaterin high pressureboilers Is nora, pureaspossible,threemainproblems v encountered' Theseproblemsareserious andcanleadto Lxtensiveand,*p..rri,ne damagr the ancillaty componentsandcansometimes leadto injury of ttreengineroomstaff, As th
il:'F::';ll?::'ffit3frl;Hgi*f
loo..tprocedure,*h,ndearingwithth
(1) Scalebuild up on theinsideof the tubes. (2) corrosion of the feedsystemand the boilertubes. (3) carry over of solublesaltsandsuspended saltsto thesuperheater andt'rbine brades. The main causeof the problemis not carryingoutpropertestson a regularbasis (most shc daily) to checkfor ph value,oxygenand co2levelsin thefeedwater,poor maintenance of to
tr*lf.:#:t1"1ffiff"::chemicils
47.
ensure limitsarekepno,r,. recommended revels as
Dissolved Solidsaresaltsthatdissolve in water,these boiler walls whenthereis an unusualconcentration sarts(chloridesalts)aresometimes< of heat. susnendedSolidsaresaltsthatdo not dissolve in waterbut arecarriedaro'nd the boiler water systemin suspension, an theseparticles*r rupf;;;il;;""*.r. (Iron and coppero_x Why is the scaleundesirable? (l) corrosion - takesseveralformsbut themostseverecasesof oxygenpitting can leadto r failures' corrosion in the closedfeed ,y*.* of highpressurewater-tube boilersplants the transportof corrosionproductsof coPPER*o lRoN into the boiler. Hard, iron ar
giving rise L"',st, roani ffi'HLT:1;ii:,Hi,:'j'#:n::frli,H,'J**";;i,
48'
(2) Impurities - ( solubleandsuspended solids) - trougt t in with the feedwater concentrate reacha concentration wheresolublesalisunasusfendedsalts .. are carried or ilHl"ntually This can resultin depositsin thl superheater andon theturbineblades. why is the boiler water testedand what testsare madeand how often? To ensurethe waterpH is not acidicand thatthechloride*d iDi readingsare in the prescr
phospiat. oDaD (ejcaustic Fl*'llXil?dJ?filllb;H:3, atri;;ine(e) /
Dailv Boiler Tests. 100ml sampleof filtered boile, *ate, Add l0 dropsofphenolphthaleinindicator samplewill turnpink if alkaliniryis > g.4 Add sulph'ric acid,strength0. 02N from a me€rs'redb'rette until the samplegoesclear. ppm CaCo3:ml O.O2Nx l0 Chlorides Retainabovesample Add a few dropssulphtrricacid o.o2N to ensure solutionis no longeralkaline. Add 10dropspotassiumchromate. Samplewill turn yellow. Add silvernitratefrom a measuredburette until samplejust turnsa brick red colot'. Ppm CaCo3 : ml silvernitratex l0
IDS 100ml sample ldd l0 dropsof phenolphthaleinindicator. Neutralisewith I drop of aceticacid lT. a samplein pot & fitto conductivity meter. Takea readingof meter - temperaturecompensate andreadoffscale. ( VanadomolybdateTest tLq!@ ) Place5 ml distilledwater in r 0 ml left hana tube. Place5 ml Boiler water in r 0 ml right hand tube. Topup to 10 with reagent- Stopler and shakeandallow to standfor 3 mins. $ Placeleft hand tubein L.H. sideof lovibond competitor Placeright handtube in R.H. side of lovibond compactor Hold up to light andfind colour match - take readingof cardin ppm. (colourmetrictest) @ Thoroughlyrinsesamplebottle with the water to be tested. Arrangetr;rro50 ml nesslertubesside by side Add 0'2 ml of thymol blue indicator soiution from a graduatedglassdropperinto theR.H. nesslertt Add 50 ml of sampleto the R.H. nesslertube. Add 50mlof sampleto the othernesslertube. (This is theblank) Placethe samplecylinder in the R.H- compartment of theNessleriser andthe blankcylinderin the compartment.
ilff,ffilii,fi:#,il;ffiffiTffi:'*.the
corours intherwo windows using aconstant right s,
Hvdrazine Reselve. Arrangetwo 50 ml nesslertubesside by side. Agd 15ml hydrochloricacid 0.5N ,t "rreilhto eachcylinder Add to the R'H' cylinderby pipette zs iitof sampleandmix with a glassrod. Add to the R'H' cylinderby pipette l0ml of dimethyl,amineamineberzaldehydesolution andthoror mix. Add to L.H. cylinderby pipene 35 ml of sample andthoroughlymix.
ftfiliifrT::H"ffi,*|"
"' cvlinder in theR-H.comparnnent ofthenessleriser andtheL.H.cyri
Matchthe samples4gainstthe colo'rs of the disc. Disc readine : ppm hydrazine ml of sample
49.
what is the purposeof adding chemicalsto the boiler water? To increasethe alkalinityor thJphosphatereseryeor to actasa Coagulant.In other words to mainti limits requiredby the manufacturerof the boilerandto minimisedamageto the plant.
50.
Explain how the water levelin the gaugeglasscanbe verified
I E
t t
as correct.
Close2 &3 and0penI - If freeflow from gauge thendrainis clear.Open2 - if free flow steam connection is clear.(No waterlevel in glass) Closez-------Open 3 - freeflow from ar"i", water connection is clear.Notegaugeglasswill be showing full. Finallyclose3 andopen2leaveio allow gaugeglasslo retumto workinglevelagainthenclose I and open 3, levelmaybeslightlyhigh until water temperaturereturns to normal. Seeblowinggaugeglassnotes 32,33.
51.
If you find no visible water in the boiler gaugeglass what immediate action should be takeni If there is no automatic shut-offof boiler nir to birners then shut-offthe fuel manually. sound tht Engineers alarm and call the Chief Engineer. Blow the gauge glass to seeif there is iven the slightest bit of water in the gauge glass. If no water Do Nor ADD WATER until the correct level oitt. boiler waterhas beenestablishedbecausett shock of adding water to overheatedboiler tubescould collapsethe boiler tubes.It is better to let tl cool naturally to their working temperature.
52.
Why is the presenceof oil in the boiler water most undesirable? (a) Cuts down the heat transfer when oil adheres to boiler tubes(internally) (b) Causespriming resulting in water and oil carry over to the superheatersand turbines. (c) Combines with suspendedsolids in the boiler waterto producesticky deposits.
53.
why should oxygen content of boiler feed water be reducedto a minimum? (A) Attacks on boiler metal resulting in pitting anddepositionof iron oxide on the boiler tubes. (B) Corrosion of the condensatesystemto produce iron and copper** in the condensate. *:$ copper is attacked by ammonia in the presenceof oxygen.
54.
How can this be achieved when an open hotwell and feed systemis used ? (a) By keeping the hotwell temperatureat approx. 90 degs.c. The oxygen content of water at 50 d is approx. FOUR times that of 90 degsC. (b) Ensure deaeratoris functioning conectly. (c) Stop air leaks into condenser,condensate systemand boiler feed system. (d) Ensure the correct level of Hydrazine is being addedto the deaeratedfeed water. (e) Introduce Amines into the low pressure/temperaftue part of the feed system. (f) BV floating polysryreneballs on top of the tank.
tJ.
rf the plant is un-manned, what would be provided to raise the alam r'if the rsv water vv"rr/r level rrevrsrr'' in the rrr' I
too low or too high and how often are these tested?
Mowbray float alarms. Leveltransmitters.Testedweekly. Foxboro (Pneumatic)High /Low level trips.Tested*r.kly.
56'
what causesfires to start in boiler uptakes.what are the hazards.How are they deter actionsshouldbe taken? Build up of sootdepositsarea causeof fires,possibly causedfrom faulty sootblowers. They aredetectedwith temperafiresensors - thermometers or similartype devices. The hazardsarethat if left unchecked thefire maydevelopinto a hydrogenfire The actionto be takenis:_ 1. Shutdown the boilerfiresandclosetheair registers. 2' Shutdown the F.D. fan andensurevanesareclosed.( alsostandby fans ) 3' Increasefeedflow througheconomisers (if fitted),blowingdownthe boiler drum as requ
57'
on a steamship,what are the main reasonsfor using the main engineturning gear? To ensurethat the heatis evenlydistributedwhile*u*rling throughandthat turbine rotors c to pressurein the maincondenser (underslung varieties). To aid in gearboxinspections, shaftbearings-etc.
58'
Describehow to prepareand flash up a highpressure water tube boiler. 1. open drum ventsandeconomiser vents( if fitted). 2' Fill boilerto oneinchin glass.( enstueall drains on waterdrumareclosed). 3. Opensuperheater vent.(Recirc). 4. Opendrainson superheater headers. 5' Setfuel oil rail up onHFO if steamavailable, otherwiseflashup on DO. 6. Line up atomisingsteam. 7. Line up forceddraughtfan. 8. Ensureair heateris by-passed. 9' Flashup the boiler on smalltip at lowestrateaccording to manufactures recommendatior steamgraduallyleavingdrurnventopenuntil steamissues at approx.2bar.Superheatervent until flow is guaranteed.( Boileron line ). 10. Testall trips puttingboileron line.
59'
Describethe warming throughprocedurerequired prepare to the main turbines from c to ready to start of manoeuvringincludingchecks and tests. 1' Run main lubricatin-soil purnpsensr:rinfalltemperatures andpressuresare normal. 2. Startthe main circulatingpump. 3. Engagethe turninggear. 4' open up the glandsteamto maint?inu positivepressure aboveatmosphericat the turbine 5' Openthe steamto thefirst stageair ejector.( mar.vac 10ins ) 6' Startthe main condensate pumpensuringthecondensate re-circvalve is open. 7' open the auxiliaty exhaustfrom theauxiiarycondenser to the main condenser. 8. Ensureall turbinedrainsareopen. 9' Openwarmingthroughby passvalvesonthemain steamline. 10. Rotateturbinesby meansof theturninggear. I l ' Graduallyincreasethemaincondenser vacuumby slowlyopeningup steamto the air eject until fully open. 12' Adjust glandsteamasnecessary to keeppressure just aboveatmospheric. Checkoperationof varioustrips associated with mainturbines.i.e. overspeed,low lube oil, lr Dependingon the installationtheremaybevariousother trips fitted.
60. How is the main turbine prevented from over speeding and what trips would need to be reset? The main
n'bine has an overspeedtrip ( normally . ,pJ"d hmiting u.n to, ) to prevent overspeed caseof a coupling failure or the ship's propellet "I"-irrg the wavm o*ing rough seas. The trip ur fitted with three independentcircuiis, which sense trre turuine speedby meansof pick ups mo'nte, turbine pedestals,aod receive a speedsignal from three pulses iroauced by a tootled wheel. The shutsa numberof control valveslo.ut"Jin the steam chlst, which is an internal part of the H.p. tu the overspeedtrip operates,the boiler safety valves may lift, due to a suddendecreasein turbine lo when the trip operates,the mechanical movement alters the position of the trip switch which then energisesthe uppercoil of the relay and at the same instant dL- energisesthe lower coil, thus chanl position of the relay. The coil of the solenoid valve is thus de-energisedand the spring moves dov the oil pressurekeepingthe manoeuwing valve open is lost. Simultaneouslyvisual and audible alt activatedand the particular trip is indicated. After the trip has been reset, (the fault being rectified) resetswitch is madewhich energisesthe lower coil of thl relay, and the solenoidvalve is repositio: protectionsystemis thus reset. Any number of trips can be built into the system.
61.
Explain how the final superheated steam temperature is controiled on a high pressure/high temperature water - tube boiler and why is it necessary. Attemperatorsare usedto keep the final superheat t"mjeran r.s within the desiredlimits. It is necr control the temperafi[e to protect the superheater tube materials from overheatingand to reducetht depositsformed on the tubes.
62.
Describethe routine inspection you would carry out before taking over a watch on a manned room of a steamship. Seequestion33 In addition :_ check deareatorlevel, check F.D. fans, bearings etc.,. Checkair heatersand economisers. Inspectboiler water levels and automatic combustion controls including fuel oil temperaturesand pressures. check aroundturbine manoeuwing controls lookin g attemperatures and pressuresand for signsof r lights etc. (Gaggedvalves ). Checkmain condenservacuum. Checkgravity tank overflow sight glass.
63.
Give the various operating pressures and temperatures of a steam propulsion plant you may t familiar with.
64.
\ilhy is there a vacuum in the main condenser? Thereis a vacuumin the main condenserto improve the efficiency of the plant, i.e. to get more wor of the steam.
65.
Give reasonswhy there may be some loss of main condenser vacuum and why is this undesiral l' If condensatetemperatureis below the saturation temperature of the condensri- ai, leakageinto condenseror incorrect operation of the air ejector. 2' If cooling water temperaturedifference is greater than normal - insufficient cooling water, or bloc tubes. 3' If cooling water temperatureis less than normal Dirty tubes, or in the extremecase,division pla washedaway. 4' lngressof air at L.P. turbine gland due to insufficient gland steam pressure. All the abovetoubles causea loss of vacuum and raises the exhaust temperatue of the tubine. This lossof vacuumcausesa loss of power and a loss in plant efficiency. The efilectof a suddenloss in vacuum will be to lift the relief valves on the flrbines. over pressu The L'P' turbine and the condenserare undesirable hence a safety device shutting the steamto the flrbines is required. To continuerunning under low vacuum condition would mean having a higher exhausttemperattu
which can causethe L.P. turbine to hog when fitted with an underslung condenser,thus produc thermal stesses. The limiting exhaust temperattrre is 77 degs C for cast iron and g2 degsC for casings. Loss of Vacuum Trip ln order to improve the efficiency of the turbine, the condenser and hence the ttrbine exhaustis rur very high vacuum(about 730 mm Hg ). This means that the saturation temperatureof the steam 50 degsC. Ideally a turbine should be designed so that at the exhaust the steam i, dry saturated.SI condenserpressure suddenlyrise i.e. the vacuum fails, then since the heat content of the steamis tl and the exhauststeamtemperafltrehas risen to the new saturation temperatrue, the steamwill now I Thus the exhaustconditions have changed, since instead of dry saflrated steam at about 50 degsC have wet steamat a temperafttrein excess of this. This change of condition will causesuddenove of the last few rows of blades,the resulting expansion causing possible blade rubbing. Furtherto tl will also be very rapid erosion as the high speed L.P. blades strike the water particles. To preventthis from occurring a vacuum trip is fitted which closes off the turbine steamsupply sht vacuumfall below a presetlevel. ( usuaily about 50% )
66.
Describethe procedure to start up a turbo-alternator from cold until it is ready to be connect switchboard including trips to be tested and reset. Stan the TA condensercooling water pump. Circulate air ejector/glandsteamcondenser (if fitted bv means of condensate pump, ensuringrecir ) is open. with the useof the priming pump, pump oil round the bearings and the gearbox sprayersensuring pressuresareregisteringon the gauges. Raisethe condenservacuum to 60Yobymeans of the air ejectors and the gland steamand openup t exhaustto the atxiliary condenser. Crack openthe mastersteamvalve having first made sure alt nrbine and line drains are fully open. Adjust steamto H.P. and L.P. glands as necessary until small amounts of steamissue from the glan, Checkoil levelsin the sump and ensuresalt water cooling is lined up to the L.O. cooler. overspeedtrip shouldbe testedevery time the machine is started. one engineer should standby tht mastervalve while anotheroperatesthe throttle valve. The L.O. hand pump should be operatedto e the steamconfol valve to open and allow steam into the turbine once the throttle valve is crackedo Tubine drainscanbe easedin but not closed. By means of a special tool pressingon the governorI the machinecan be overspedand the revs noted for the log book. Once the overspeedtrip haswork delayre-settingof the trips until machine is at approximatlly 40%of the normal speed. CheckL.O. temperatures'Resetthrottle/emergencyvalve and progressively open master steamvalve until appn turn open' Bring machineup to full rated speed by means of the throttle valve and ensuremasterva fully opened' Raisevacuumto morimum. Close all drain valves. Machine is now readyto parallel on boards.w. valvesto L.o. cooler etc. can be regulated to suit. Trips fitted are;- overspeed- Low L.o. - Back p-rr*" trip.
67.
What are nodesand anti-nodes?. Within a vibrating systemcertain points that do not move or have zeroamplitude are called NODES points wherethe amplitudesof vibratory movement are at a ma:
68.
when coming into port, how do you change over from HFo to Do? The methodof changingover from HFo to Do will vary from vessel to vessel but a commonmetho use of a mixing chamberwhere-by the viscosity of the iuel is "sensed" by the viscometerand the he automaticallyremovedfrom the heater as the DO filters through the system on its way to the fuel oil cool graduallyand preventthermal shock to the materials of the engine block etc. Fuel suppliedto motor vesselsis usually of the high viscosiry rype. This kind of fuel is a blend of low-viscosity distillate and high viscosity residual oils . The b'nker sr
has tableswhich give the proportionalamountsof eachkinq of oil requiredto obtainsomespecif viscosity' After the proportionshavebeenestablished the blendis producedby usingrwo pumps aranged to dischargeinto a commonpipe. Thesizeof thepipe is suchthatturbuleniflow takes 1 the two tlpes of oil becomewill mixto.-th. speedof thetwo pumps is setsothatthe proportionr kind of oil passinginto the commondischarg;is maintainedclnectly. Distillatesfrom onecrude do not always blend well with residualsfrom another.This occurs whenthesmallerpart is not sc the largerpart' If incompatibleoils areusedto producea blended fuel,precipitationwill occur.Tl itself in the operation of the centrifugalpurifieis whichquickly fill with asphalticmaterialandexr difficulty may be experiencedin maintaininganadequatlthroughput of fuel throughthe purifier I requirementsof the engine-This problemis well rcnown n et oit suppliers andtheytakeevery( 1o blend compatibletypes of fuel. Normally fuelsfrom different ro*.., shouldnot be mixedaboar blend that is compatible in itself may not be compatiblewith a blendfromanotherorigin, andpre may occur.
69.
what is cavitation and where would it appear? Cavitation is the forming andburstingof vapotu-filledcavities or bubblesandit canoccurasa res pressurevariations' Found most commonlron shipspropellers dueto presswevariationson the b propeller bladesthe result beinga lossof thrust,erosion of the bladesuface,vibrationin the afterl the ship and finally noise- It is usuallylimited to high speedheavily loadedpropellersandis not a under normal operatingconditionswith a well designed propeller.Anothercomponentsubjectedt cavitation will be centrifugalpump impellerr,.rprJiuty condensate pumpsusedin dry-sumpcond
70.
which bottom end bolt would you expectto fail first, a bolt fitted to a four strokeengineor a fifted to a two stroke engine? Likelihood of bottom end bolt failing on 4-strokeenginefirst due to thevariousstresses affectingt (Seeattachednotes) Simple stress:Comesabout from some staticform of loading,andthevalue of thestressdoesnot change. FluctuatineStress:Diesel engineswhen operatingarenot subjectto staticforms of loading. Dueto cylinderpressure variationsand dynamic effectsof the -orrirrg partsthe forces actingon *y partof an enginearea1 changing' As the forces changeso the stresses in thevariouspartschange.Thechangingvaluesof experiencedon parts of a machinearereferredto asfluctuatirrg ,t .rr. et anyinstantin time the va stresscan be relatedto a simplestress. Alternatine Stress:Is said to occur when the value of a stresschangesfrom somevalue of tensilestressto a similarvalr compressivestress' The exampleis the overhungfly.rvheel wherea particlein the shaftsurfacewill changefrom tensile loading at its uppermostpositionof rotation to .o*pr.rrive loadingat its lowes The overhwtg flywheel may be consideredasa cantileverwith a concentrated load. C)'clic Stress:when a certainpattern of stresschangerTeats itself at equal time intervals(for example,eachrevt of an engineof shaft) the patternof stressis refenedto ascyclic stress. Fluctuating' alternating' of cyclic stressesareof greatimportance astheyareverycloselyassociater a form of failure of machinepartsknown asfatiguefailurl. Alternatingof cyclicstresses aresometi referredto as fluctuating stressesasa generalt.trn to distinguish themrrornsimplestresses.
71.
How is a fuel oil burner with steamatomisation,prevented from beingremovedfrom the boilt the fuel and steam are still flowing? Mechanicalinterlock situatedon tof of burner i.e. whenfuel and steamvalvesarein the openpositi burnersare coveredand cannotbe removed.
72.
what happenswhen a condenserlosesits vacuum? (Seequestion65)
73.
why should you not run an asternturbin_eon superheated steamfor extendedperiods? Not designedto rur for periodslongerthan30 minutes ashighert.*p, involved**ta affect ex1 the LP rotor with the addeddangeror uua. rub and subsequent dam4ge.(Materials& Tolerance
74.
why are intercoolersfitted onto air compressors?
i1'.'ff!,;1h:ffii:'*:"#ffif[:ff#ssed
ai,tobecooredafterthe various stages thus ir
75.
Why is boiler furnace air heated? Heating the air prior to entering the furnace increasing the thermalefficiency of the boiler by impr combustion process.
76.
what safety measures are fitted to protect a steam turbine should a blackout occur? Gear driven pumps on most modern pt*rtr (Stal-Laval) driven offthe main gearbox ( press,re /ga system) or gravity tanks situated at the top of the engine room provide adequatetime to bring the t to rest in the event of a blackout.
77.
Describe turbo-charger surging. Turbochargers sluge when thty are uying to deliver more air than they can suck in. The causes afi usually blocked intake filter, failure to open cooling water valvesfor the chargeair intercoolers. L bangs are heard from the scavengetunking. (Not *tit. sonic bangs.)
79.
What is a hi-jet valve? Hi-Jet valve is a PV (pressure/vacuum breakerfound on all cargotanks and fitted to prevent vacu ) pressure conditions arising in cargo tanks with possible structuraldamageresulting to the tank. Flame screens prevent the ingressof sparks,ligirtening etc. into a flamniable atmosphere. The gast be cleared to 3 meters above the deck.
79.
How do you test main engine trips and how often are thesetestscarried out? when running up Main Engines various t ips can be testedby simulatingthe trip devices, i.e. over low lubricating oil pressureand high Jacketwater Temperature.
80.
Describe the process of tran-sferring heary fuel oil from a double bottom tank to a seftling tan ** Ullages of all the tanks before"oriro.rr.irrg ** ** Checklists** ** Oil RecordBook *:F * * communications ship to shore,if appropriateor Bridge and engine room senior watchkeeping of -,r* ** Don't rely on gaugesfor final ullages itopping off Record all transfersin log book as well ; record book 'F* Regular checks** *tspitt gearat ** the ready Take soundings /ullages of any tanks supplied from the commonline. check all valves before conu the bnnker operation' If necessarylash ctosea any valveswhich could accidentallybe opened. Line. correct transfer line' Inform duty engineerand Bridge that transferis aboutto start. start pump and
:1l?',Y:Hi?tr::$j#s
toconfirm nowisconect. Dothisonaregurar basis. Have spnrsear
If transfettittg to two tanks at the one time restrict flow to one so as only one tank to monitor when finishing.
81.
is the purpose of fuel oil settling tanks? YnI Settling tanks are used to allow any water which may have enteredthe tank accidentally with the oil leaked via a heating coil to "settle out " where it canbe drainedto the oily bilge. They are fitted witl heating coils to allow the oil to be raised in temperature for easeof transferto the daily service tank normally through a p'rifier. The temperatureshould be restrictedto app;. 5l deg c ( 125 deg F temperahrre should be restricted to approx. 5l deg c (l2s deg F )
82.
why are weightedcocksfitted to oil soundingpipes? weightedcocksarefittedto oil soundingpipeson aouule bottom tanks ro ensurea positiveshut-o In the unlikely eventof thevesseltouchingbottomand the tank being holed, seawaterat pressure enterthe tank anddisplacetheoil out via the soundingpipe.
83.
Where and why are quick closingvalvesfitted in a fuel systemand how can they fail to operr Quick closingvalvesarefiuedto thesuctionlinesof all fuel and lubricating oil tanksso that in the of a seriousfire in theengineroom,thetankcanbe isolatedin the event of the pipelinemeltingin It would alsoallowthe engineto stopdueto lack of fuel if the engineroom had to be
84.
in an engineroom? lnv are oily-waterseparatorsnecessary Seequestion14.
85.
What pumpson boardshipcanbe usedto pump out engine room bilges? SeequestionI 1.
86.
Give possiblereasonswhy an engineroom bitgepump may not be able to empty bilges. Seequestion12.
87.
What immediateactionmustbe takenif a fire in the engine room is seriousenoughto havetr evacuatedby all personnel? Seequestion6.
89.
Where would you expectto find the emergencyfire pump and what is a very important valve makesureis closedif thepumphasto be used? Fire pumpusuallysituatedoutsideof machineryspacenormally in the Forecastlebut sometimesin steeringgearcomparEnent. Whenrunningensureanchorwash valves are closedto boostpressure.
89.
Describethe procedure,beforethe start of a voytge, to ensure that the steeringgear is operatr satisfactorily. Checkfor oil leaks - Checkfor looselinkages/pins etc. - nrn pumps individually 30 - 35 degsin 2t seconds'Testmeansof communication betrveenbridgeand Sieeti"g gear. If possibletestalarms..
90.
what gasesmay be foundin emptybailasttanks? Hydrogengasmaybepresent, withpossiblyC02.Lack of oxygendue to oxidationin the tank.
91.
What is the dangerwhenusinga spirit lamp to detectleakage of freon gas? It decomposes in contactwith flameio giveproductswhich are pungent and poisonous(Chlorine & Phosgene ).
92.
what type of clutch is usedon an electricwindlass? Dogclutchor electricallyoperated magneticclutch.
93.
What meansare takento ensurethat the lifeboat enginewill start in any climatic conditionssr extremecold? Arctic fuel ( low pourpoint) - spaceHeaters(intrinsically Safe) Insulatedenginehousing- Electricalglowplugs- etheraerosolcanAnti - Freezeinfreshwatercirc systems.
94.
what meansare providedto preventoverspeeding of the lifeboat when it is beinglowered? CentrifugalBrakeon Falls.
95.
Describe how you would checka BA set. (A) Check all strapson maskareO.K. & checkconditionof maskglass. @) Pressdemandvalve (button/lever). (C) Check boule connections. (D) Check openingof main valve. CE)Turn air on andoffagain. (F) Pressureshouldnot drop morethan l0 bar in two (2) minutes. (G) Test alarm,pressdemandvalveor hold maskto faceandbreath. (H) Check tightnessof faceseal.
96.
Having reassembleda pump you saw water slightlyleakingfrom a gland packing-- would yor up to stop the leak? No. On packedglandsit is quitenormalto havea slightleakageof water.
97'
What temperature would you expect on a M.E. exhaustand what deviation would be a Under full load conditions. - 350 - 400 degsC Marimum of 50 degs differential.
98'
What temperature would you expect for the M.E. lub oil in normal seruice? About 40 - 45 Degs c ( outlet 0 - 3s - 40 degsc. (inlet )
99'
What temperature would you expect for the M.E. JCW ? What may happen if the teml low? outlet - 65 degs C Inlet - 55 degsC. Too lowthermal shockingmayresult. Leakageof wa expansion pieces with the possibility of water leakagethroughtf,e sealingrings etc.
100.
If the S-'lry'.cooling temp was too low what effect could it have on the M.E? Cools down Lubricating oil, jacket water chargeair and if cooled down too much will affect L.O. (cold plugging in L.O. coolers) and causethermal shocking and cold temperaturecorrosion.
101-
How would you start an auxiliaty diesel engine (manuat)? What would you suspect if the engine failed to start on air? What would you suspect if the engine failed to start on fuel? Take stand-by machine off..auto start', Turn stating handle to stop and open indicator cocks. Check sump and governor oil levels. Lubricate rocker gear with oil can. operate had priming pump and open air start valve. Blow over engine. Run up engine by turning handwheelto "Start" position. When engineis turning at speedtun to "Run" position. Shut air start valves. Check oil and water pressures. Open sea water cooling valves on engine. Startpump if necessary. Checksafeflow of fresh, water on flow sight glasses. Switch on alarm/trip panel in control room. Machine is now ready to parallel.
102.
What would you do in the event of a scavengefire? ln the event of a scavengefire the bridge most be informed as should the Ch. Engineer that . to be reducedto D. S. Aheadimmediately. lncreasecylinder lubricationto all units by increasingthe mechanical lubricator flow to max Take fuel offthe affectedunits by lifting the fuel pump rollers or suction valve offits seat ( r what type of pump is fitted). Shut off nozzlecooling (if nozz,le is oil cooled). By increasinglubrication thereis lesschanceof the engine seizing due to being overheatedt by taking the fuel offthe affectedunits the heat developed due to combustion, is reduced wh the fue more chanceof burningitself out. The scavengedrains shouldbe closedto prevent any sparks entering the engine room which further risk to personnelin the viscinity. If the fire is of a more serious nature the engine will stopped,the indicator cocksopenedand the turning gear engaged and the engine turned. Thr spacefixed fire fighting installation(C02, steamsmothering etc) can be brought into use to e fire. Scavengespaceshould be examinedto ascertaincauseof fire before restarting the engine. P should stand clear of relief / explosiondeviceswhere fitted.
103.
How often would you inspectthe scavengedrains? What do you expect to seecoming from the scavengedrains? What scavengeair temperaturewould you expect? (a) Every watch (b) A little water with possibly a little lubricating oil. (c) Approx. 40 de1
104.
How often do you blow gaugeglasseson a package boiler? How often do you blow down level transmitters? Packageboiler gaugeglassesshouldbe testedwhen put on line and at any time when there is least once a week to ascertainwherethe correct level is. Level transmitters shouldbe testedwhen the boiler is put on line and approx. Once per montJ
105.
How often do you blow gaugeglasseson a water-tube boiler? How often do you blow down level transmitters? Watertubegauge glassesshouldalso be testedwhen put on line and in the case of very high t boilers with the bulls eyetype of glasscan usually be tested on aregular basis, but forthe nor pressureboiler gaugeglass,greatcarehasto be taken when blowing the glass in casethe mic and the glass leaks. Glassesshould be testedonceeverytwo weeks and with twin boiler plants, one boiler every 1 Level transmitters shouldalsobe testedwhen the boiler is put on line and approx. every mon
106.
Describehow you would start aTlAfrom cold condition Why do you use gland steam? What trips do you have on a TIA? How do you obtain a vacuum in the condenser? Why do you need a vacuum? Seequestion66.
107.
Passingthe fridge unit you seebubbles in the sight glass, what do you suspect? Large bubbles in the sight glassmay indicatethat the system is short of gas. When the syste: chargedthe sight glassshouldbe clear and the dischargepressure normal, depending on the s temperature. Small bubbles in the sight glassaccompaniedwith a high discharge pressure would indicate a system. How would you remove air from a fridge system? Shut the outlet from the condenser/receiver and allow the refrigerant to be pumped down. Thr will cut out on high pressurewhen it is pumpeddown. The air can then be removed by openi the top of the condenser.
108.
10e' il" ili*::THJhi:l Ensue
"" asvstem, it hasa mi\ quariry about it (a)wourd yr il
thatthet'9' nTfier is opera:ing co:rectlyand that the correct gravity disc is
bein theoilshould ue it rieht to continue iriuse iithe source *iir";illT'ff]].Hhan8ed r
bewarer conraminatior ffi.iil:r?:*:,fiYi::|,il":Slsincation ortheL.o. caused 110. Bo'er water tests--what are you looking for? what testsdo you carry out on a water tube boiler? why is it necessary. to reduceo{ygen in the feed water? How is the oxygenlevel".Au..Jl statethe formuraefor the chemicars used To checkthatthePhof thewateris at the recommendedvalue. Thatthe TDS is notroohigh. Thatthechloridesin theboilerwater arenot too high.
;"#i;;*" recommended rimit(Hydrazine fffrfr:ffn::l;:ff;';;i13: readi: llf: Testscarried out are:_
*t$ilyir:Hfs'
TDs'Phosphates, oxvgenandHvdrazine. causticalkalinityshourd a
It is necessary to reduceoxygento preventcorrosion in the boiler fubes,corrosionin the copperis attackedby ammoniain fet the prescience of oxygrrr. prevention- Ensure i;; question4g ). i thatthedeaerator is working efficiently. stopair leaksinto the condens.r, ,iniensate systemand boiler feed system. Enstrethecorrectlevel of Hydrazirr. i, being addedto the deaeratedwater. 111'
why do we superheatsteamin the
;:ffi"::tf;lf:'*tlff
boiler and then desuperheat
it before use? b"iil;; thatther,.u* "* store moreenerry, andarso thestea
The p'rpose of a de-superheater is to reducethe temperature of a quantity of superheatedste suitablefor auxiliary servicesrequiJrrg low temp";;r" or sat'ated steam. ll2-
why do you take power cards on a M.E.? How do you work out the poro." p.r cylinder? Power cardsare takento enstue thai eactrcylinder is developing roughly the sameamount o: engineis in a balancescondition and the exhausttemperatures should be within 50 degs c oI
,:ilT;il,:'#Hl,iiil*:#,';,';flH:il:#i:mx*ffi ::,ffdiagram,,hen
-Theformulafor indicatedpb*., is;_ P = MeanEfifectivepower L = Lengthof Diagram A = Areaof Diagram N = Numberof Strokes [13'
why do you needto coolthe air from the T/c before retuming it to the scavenge In orderto alterits densityandincreurc ngespace? irr massno* to the cylinders. Thegreaterthemassof air supp[J;; rh..yrirra.rs; ,h" greaterthe amounr of fuel which can thereforethegreaterthepoweroboin.a.
14- If the steeringsystemis overroaded wourd it trip out?
mffiilrh:Jn'TJ#iJ*:*ixl.*ffi*H:**rabrethatthemotorkeepsnu
ll5.
why is it necessaryto have tappet crearance? what would be the effect if th; clearancewas too rarge? What would be the effect if the clearancewas too small? To allow for the expansionof the materialsof the elgine components astheenginewarm operatingconditions- Tappetclearanceshouldalways becheckedwhentheen1 Afi]""* Too largeclearances_ (a) Excessnoise aro'nd areaof the rockergear
tlJil:#ff:J"_
oo""tullvcausing poisible backpressure andtossinengine thermat
(a) Valve held offseat, once a valve has startedto leak, from any cause,the passage of hc areaof the seat causes distortion which then increases the amount of leakage.The ter: valve and seat in the area of the leak rises considerably, the strengthof the metal is im1 resistanceto erosive effect of the hot gases is seriously reduced. buring the combustic high pressure in the cylinder expand u.ros the location of the leakageat very high ve1
;ffi:"*J$Hfil?:H*T;;ff.10*n,
thecombustion perioiy increases very r
116. why are there three water supplies to a purifier? Bowl sealingwater. Operatingwater. Controlor sludgingwater. It7 '
what safefydevicewould prevent an explosion in the starting air line? Relief valvesin the line, bursting discs flame traps. ,
118. Explain how a fusible plug works when the temperatureortne fusible plug attains a certainpoint it will ruptureandrelievetl line. 119' why is a steam/steamgeneratorfitted? why doesit havea separatefeedsystem? To supplylow pressuresteamfor the auxiliaries. It hasa separate feedsystemsothat4n! cr
[HJr"rfi1X-;:ti'.i'j; ,T,jlnot
beallowedbackto theboileiwaterfeedwhichcourd ,rrulti
120' If there is excessivewater discharging from the purifier what is the problem? Possiblywaterin the settling tanks, rculing water supplyleft on. l2t.
How do self cleaning filters work?
122. why are purifiers contained in a separate compartment? To allow the fumes from the oils being separateJio ue extractedby a separate extractionfan fumescontaminatingthe engine room. t23'
How doesa water transducer varve work? In the ALCAP p'rifier it sensesthe presence of waterin the oil dischargeandopensa water r releasethe excesswater if the purifier is in between sludgecycles( of 15mins)
124. what is the purpose for a back pressure in a purifier? To maintainthe position of the oilwater interface which hasbeenestablished by thechoiceo 125' Explain what safety features are on an electricalstarter box?
ff ffi*H:ffifi0;.oo"tted
unless themainbreaker hasbeen switched off.Thisisdont
126, Describethe safety features on a main engineswitchboard? 127. Give two reasonswhy an air compressormay run hot An air compressormay nn hot if the lubricatini oil cooler( if fitted is blocked,or if there leak,causingthe machine to rwt continuously#tnout uuoaaing, ) or if thesuctionfilter is I is a problemwith the valves. 128. Describehow you wourd test a smokeararm To testa smokealarm' inform the relevantpersorurel, pick a time wheneveryone,s about, r aerosolwith adapterand spray head. 129. what action would you take if a purifier lost its seal. If the purifier loses it's seal' desludgeoil to recirc,fill with seal water,allowoil to enterbor Ensuring back pressureis correct. ir rtitt not sealinginvestigate furtherby checkingcorrecr beingusedor that the clutch mechanismis not slipping. (Chlck motor/drivespeed.) 130. How do you know if a purifier is up to speed. To checkpurifier is up to speed,checkits iell-tale (78 normal depending uponsystem)and 131' If a tube fails on an exhaust gas boiler would you (a) stopthe engine(b) reducethe eng continueat full speed. If a tubeblows in an exhaustgas boiler while at full speed, continueat full speed,bypassboi pressureto drop, allowing water to drain to bilge. Flash up aux.boilerandput on line ASAI 132' Describehow you could test the operation of the emergencybilgeinjectionvalve. To test-theemergencybilge injection severalmethodsmat belsed; ;(a) If the contentsof the bilges are cleanthenthe sea waterinlet valvemaybeclosedandtht injectionvalve crackedopen. The bilge waterlevel should beobserved to fall. (b) A damcan be erectedaround the and filled with cleanwater,thenprocedure fipe is follc (c) The suctionpipe can be disconn""t"a andreplacedwith a containerof .1.* waterbenea asin (a) . (d) A quickmethodwould be to attacha pieceof rubberjointing or a stoutpieceof plyrvood overthe suction' The seawater suctionis closedandttreiitge iijection .ru.krd openwherer shouldbe heardto 'clack' againstthe spindleandthe suction gaugeof thepumpobserved to adequatesuction. 133. Explain the difference between a purifier and a crarifier. A purifier separatestwo liquids, a clarifier displacessolids from a liquid. clarifiers v^sr^'! arefitted gravityting or solid prug (stackshaveno holesin them) 134. what boiler water tests do you carry out? What saltsdo you test for and what are their chemical fomula? what effectwourd excesshydrazine have? Boilertestscarriedout ;- T. D. S. - Chlorides- pH value- p. Alkalinity T . Alkalinity - phosphateReserve - HydrazineReserve. saltsyou testfor ;- calcium carbonate ( ca co 3 ) SodiumChloride ( Na Ct) Calcium Bicarbonate Ca ( HCO3)2 Magnesium Sulphate MgSO4 Magnesium Chloride MgCL2 Hvdrazine( N2H4) - sodium Sulphate (Na so3) - phosphate po4) ( Silica ( sio2
)
135'
136-
137'
what could be the problemif there_isoil carry over from the purifier? If thereis oil carryoverfrom thepurifierit mayLe due to rossof oil seal (faulty or worn .o, incorrectgravity disc.insufficientbackpr.rr*, too slow (e.g.sloppingclutch ) or bowl stur At full away what plant changesare made? At full - away; plant changes (Motor ) 1. Seasuctionfrom highto low 2. Wasteheatunit on line 3. power to deckoff 4. ExtraGenyoffor shaftgenyon . 5. Lub oil to normalamount 6. Arrxyr."u.ng. utower-or. 7. Evapon g. Dieselto HFO 9. Steeringgearto onemotor. (Steam) 1. Changeoverto bledsteam. 2. Feedrecircclosed. 3. St.Bygenyoff. 4. Scoopopen. 5. Asternguardvalveclosed. 6. Steamoffdeck. 7. Steeringgearto onemotor. 8 Gasair heateron.. What is the differencebetweenphenolphalein alkalinity and total atkatinity? Total alkalinity is the combinedconcentrations of Bicarbonates andcarbonatesor of carbr Hydroxidesexpressed in a commonform,usuallyin termsof calciumcarbonate. It is ofter 'M'reading. ir**t#measures
thealkalinitycausedby thepresence of carbonates, hydroxides and p
138'
Describethe symptomsof underchargein a refrigeration system. Where is the sight glass? underchargingof a refrigerationsystemmaybeindicated by bubblesin the liquid lone sigh pressureat the compressor suction.Theroomtemperafures will alsostartto rise.
139.
Describehow you would rechargea fridgesystem. when addinggasto an undercharged sysreir,ttt" g* bottleis connectedto the filling valve evaporatoroutlet,loosely.Thebottlevalveis crackedopen to removeair from the connectj tighteningthe cormectionto the filling valve. Thebottle shouldbe upright to prevent entry compressorshouldberuuring andchargingshouldcontinue rurtil trresilrrt glass is full.
140.
Describea fridge cycle. The pressureof the refrigerantgasis increased in the compressor, ( thereforebecomeshot ). passedthrougha condenser whereit-is cooledby wateror air, andfecauseit is still at a higt condense'The liquid refrigerantis thendisnibutedthrough a pipe networkto the expansion controlsthe flow of liquid refrigerantinto theevaporato,( *rfrh i, ut a lower press,re ). A cooledspacepassesovertheevaporator andboilsoffthe ,rtigri*t ( at the sametime cooli The designis suchthatall the liquid is boiledoffbefore returningto the compressor.
l4l.
State the safetydevicesfitted to a fridge compressor. A. Low pressurecut out. B. Differentialpressureswitch. C. High pressurecut out. D. safety valve or b'rsting discdepending onthesystem.
142.
Explain different typesof pumps. Positive displacement. Centrifugal Axial flow.
143.
Explain the drive linkage of a purifier. Motor - coupling - centrifugal clutch (friction pads,feroda - shaft - bevel gears worm wh ) pump with shearpin.
144'
What type of bilge pump would be fitted to the lifeboat and what would you do if you suction? A displacementpump of the vanetype or diaphragmpump. If suction cannot be attained;- i Putnp worn' if diaphragmtype, split in diaphragm. Blockage in the suction line or hole in tl Also pump may need priming
145.
Describe how the main enginelub oil is heated. The main engine lubricating oil is heatedvia the L.O. pgrifier heater.
146'
Describe the difference betweena positive and negative cam with respect to starting air pump. The differencebetween a positive cam and a negativecurmwith respect to starting air and fu, positive cam is of a circular shapewith a protozoonwhich upon each revolutior, .uur.s an ul Of a plunger in the fuel pump forcing fuel out at pressure. A negative cam is of a circular sh valley, thereforea normally closedpiston will drop and henc. op"tr a valve once every revol Where are the auxiliary blowers,where do they take suction from? The auxiliary blowers are situatedat the endsof the scavengetrunking and they take their su engineroom ventilation fans.
147.
148.
Describe the construction of the scavengespace. The scavengespaceis constructedby meansof a cylindrical tnurking with stiffeners with an auxy blowers mounted on the ends,and non-returnreed valves from the charge air cooling s1 fixed fire fighting connections,temperatureand pressuregauge connections.
149.
Why do you have two different air pressuresin the scavengespace? There may be different air pressuresin the scavengemanifold a.r"1o underpiston
scavengepl
150.
What cut outs are fitted to a main engine? l. Low lubricating oil pressure. 2. Main engineoverspeedtrip. 3. Crankcasemist detector. 4. High J.W. temperature. Dependingon plant, other trips may be;- pistoncooling pressurecylinder L.O. tank low level
151.
If a main engine alarm is activatedwill the engine stop or slow down? Varies from ship to ship dependingon the alarm *tti.t, is activated, but engine will always st, L.O., High J.W. and Overspeed.
152.
How doesthe engine stop after receiving an alarm? On low lub oil the main enginestopswhen an air signal allows high pressure air to enter the s And exert a pressureon a piston which is connectedvia the pisto;rrd to the governor linkagr Thereby shutting the fuel offthe engineand stoppingit. The overspeedtrip usually consistsof a bolt with a ielatively heary head. The bolt is fitted at end of the engine shaft where no torque is transmitted. It is fitted in a space bored out across the shaft. The bolt is held in place by a nut and is supportedby a spring. When the engine ov centrifugal force exerted by the bolt headovercomm-tir t,rppott oift" compression of th. ,p, head in the "thrown " position strikesa trip lever which is alio thrown and shuts offthe engin
153. How do you lift a fuel pump? Thetermto lift a fuel pump meansto lift_the fuel pump c€rmfollower clearof the fuel, camw Attachedto thecamshaft-This in turn lifts ttre fuet pump plungerandstopsanypumpingacti in thefuel pump. Thereforeno fuel is injected into the ryiinai-r. Themeansof actuallylifting the pump vary depending o1the type of engine. . 154. How do you reducesarinity in an evaporator? To reducethesalinityin an evaporator,reducethe level in the shell,increasethe temperature : (checkvacuum). If permanent,check condenser for leaks. Drain brine. 155. What are intrinsically safefittings? Intinsically safefittings meansu pie"" of equipmentthat will only producea sparkwhichis li voltageandcurrentandthereforeunableto causeignition. The effect of an electric arc or spark 'rPzI'\ L'u on rr'l"rurrlaDle flammable vapour vapour lS is that that the the heat heat increases i
the energy of the vapour and air locally so that particles sv evrr activated v clrw\r cruLr r- "v'vv are and ula(.le madl ready r9aqy for IOf CngmlOal chemical CombtnatiOn. combination. Thg The enefgiSatiOn eneroisa
reachesa sufficient pitch after a very small time delay so that combustionresults. A weak weak snark spark(1r,, or arcmay Pnp?atar
ic
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ir.:yently madetorwostandards of safety;_
whi.ch;q'i'"' thatsafery i, mainrained withuptotwo: *"t3::i,**:.T:*"3dfld, typeof equipmentcan be fitted in any hazardous
area. Tit Theotherstandardis giventhe symbol:_ Ex i(b) andtheapparatus madeto this specification is safewith up to onefault. The Ex i(b) producr not usedin the mosthazardousareas. Manufacturers of intrinsicallysafeapparatusstatethat this methodof protection is suitablefor elect supplies at lessthan30 volts and 50 millamps. It is usedextensively for instrumentation andsomer functions. careis exercised in design,that capacitanceand inductancewithin the electrical installationis keptr minimum'to preventstorageof "tt"tgy which in the event of a fault couldgenerate an incentivespar Ex i systems areisolatedfrom other eiectrical suppliesevento the extent thatthe cablesarenotpern bein thesametraysasthoseof other cables-(to prevent inductioneffects). systemsareearthe protectionis providedby inclusion of shunt aioal safetybarriersbetweenhazardous andnonhazardous areas'The safetybarriershave current limiting resistors andvoltageby-passing zene diodesto preventexcessiveelectrical energiesfrom reaching the hazardous areas. Neither certificationor markingis necessaryif non of the followinfvalues areexceeded in a device:l. A' 20 microjoules,25 milliwatts. However, greatcaution is neededwhendecidingwhetherapl will operatewithin all of theselimits, and any associated systemswouldhaveto becertifiedas intrinsicallysafe. FlameproofEquinment If electricalequipmentcould be madewith pgrfectly gas tight casings,thepossibilityof gasseepingi beingignitedby a sparkwould not be u probl"*. unrotn-"t"ly, seils on therotatingshaftsof motor theoperatingrodsof solenoidsare not gas tight. Hermetic sealingof coversis not grraranteed. Gask jointingcandeteriorate andfaceto face-3oini dependon quality ortrrc machined surfaces and tightu fastenings' lnaccurate threadson screwedcover;tints or ctnduit canallow leakageof gas. Soto can
deterioratingcementor sealanton inspection windowsor insulators. The designersof flameproof equipment recognise that thereis a risk of ignition and explos someenclosures andcounterthis by makingthe casingsstrongenoughto witrrstand suchar Also, potentialflamepathsto theoutsideoitttr casingthroug[.ioitrts or sealsere madeso r any flame' Normallythis is donein joints by makingthem*.iuf to metal with no intentio possibleflamepathbetweenthe surfaces aremadelong enoughto prevent flame emission, jointing is not usedin the actualflameproofjoint.The flamelath through shaft sealsis elo a labyrinthdesign. Specialconsideration is giu.n to coverfasieningswhich must be strong withstandinternalexplosion,andasfar aspossible,gastight. Screws of specialmaterialm uniquedesignsothat ordinaryscrewscannotbe usedto ,rpture them. Their headsarepattr keys. Screwholesmustnot piercethecasing.( from MarineElectrical Equipmentand practicesI 156. Describehow you operatea bulk co2system. To operatea bulk COzsystem,raisealarm,evacuate space, take a roll call of all personnel, space'all ventilationfansandcloseflaps. Trip remotefuel valvesand useremote switches Dependingon systempull leverandoperatetJleus.mechanism. 157'
What could be the causeof the exhausttemperatureof one cylinder reading higher th: If oneexhausttemperature on anengineis higirerthanthe restthe causesmay be a scaveng€ valve stuck aiar.,incorrectfuel injection,incorrectrack settingetc.
158'
When would you expectto call the ChiefEngineerif you are the only engineer on watc If I wasthe only engineeron watchI wouldcall the C/engasper standing orJ"rr, fail*re of r steering9etr, if st-byis rutg, fire in theengineroom,*ujo, spill, power failure or if in anyr
159'
Where is the BA set situated?Describethe constructionof the safety line. What speci: are presenton the line? The BA setsareusuallysituatedat theemergency stations.The safetyline has a wire coretl middle of it' Specialisedfiuingsreferto theLgr tn the line at intervals of one metre. (Chec1
160- How doesan air ejectorwork andwhat is its purpose? The purposeof an air ejectoris to createa vacuum.It works on the venturi principle. 161. How would you deatwith a fire in theboileruptake? Shutoff the burners,securetheFD fansandclosethe vanes,raisethe fire alarm and effect b< cooling. DO NOT operatethe sootblowers. 162'
What are the last drains you wouldclosewhenflashingup water tube boiler? The last drainsyou would closewouldbethesuperheater drains.
163'
What would be the operatingpressureand temperatureof the fuel oil system? Pressurewould be between5 barand8 depending on the installation. An averagetemperi !* 125 degC but this would dependuponthe qualityan; viscosityof the fuel.
164. Describean insulationtest on a 3 phaseAC electrical motor? The insulationteston a 3 phaseACilectrical motoris doneusing a meggar(500v ) to mez*r insulationresistance betweenthe3 phaseterminalsandagainstti'e motor casing.Readings sh minimum of I megohm.
165. Describea jerk pump. How doesit work? A jerk pumpis a displacementpump used on diesel enginesto produce high pressurefuel fi duringeachenginecycleby having a cam act upon the roller andplunger of thepumpto pft suppliedto thepumpon its way to the injector. 166' What problemscould occur when running F.O. purifier with different typesof bunker Whenrurningthe fuel oil purifier with diffeient gpes of bunkers,their differentdensitiesn differentgravitydiscsto maintain the seal. The temperatures of the bunkersmayhaveto be Desludging cyclesmayhaveto be changed. 167'
What is the purposeof an intercooler? (Give temperaturesand pressures.) what are the probremsof undercooling the charge air? Thepurposeof an intercooleris to cool the air so more massper unit volume of air canpass wayto the cylinders.( t bar aboveatmospheric,air at 40 degC ) If thechargeair is cooledtoo much, the u1r-uy reachits deil'poi.rt and dependingon the su thefuel, sulphuricacidmay be formed and "oia corrosior,,o"y attackthe iner. Thereforeit keepthechargeair temperatureabove40 deg c.
168. what safetyinterrocksare fitted to a lifeboat? Limit switches,centrifugalbrakesand harbour pins. 169. Describehow to (a) Lower the lifeboat. Fastenpainterto forwardbits. Release gnpsandcleargnpes.Removeany temporaryengineheatercables if usedandremo. pins.. Lowerlifeboatto embarkationdeck and pull the lifeboat into the ships sideusingthe bowsin Personnel cannow get into the boat and ieleasetricing pennants. Passengers cannow get into the boat and then the boat canbe releasedfrom the shipssideus Bowsingtackle. Startthelifeboatenginemaking surethe exhaustpipe coveris removed(if oneis fitted) andl Lowerthelifeboatinto the water. Release thefalls andreleasethe painter (b) Raisethe lifeboat. Connectthelifeboatfalls. Hoistthelifeboatto the embarkationdeck and stop the engine. Connectthetricingpennantsand pull the lifeboat into ttre stripsside. Disembarkall occupants. Raisethelifeboatontothe davits until the hoist motor is cut out by the limit switches. Hoistthelifeboatup to its secureposition by use of the handwtreetand securethe gripes. Removetheplug andfit the harbourpins. 170. what is (a) The tricing pennant? (b) Bowsing tackle?. Tricingpennantpulls the boat into the side of the vesselwhenlowered to the embarkation der Bowsinetackleis usedto allow the boat to be releasedslowly from the shipssidewhenthetn pennants havebeenremovedafter the boat has beenfill with personnel.
l7l'
Describethe bridge operation and local operation of a watertight door. Brideeoperation.The doors are placed on remotecontrolfrom ttri uriage. If thedooris ir positionan alarmwill sound and a light will flash on both sidesof the doorfor 3Osecs befo closes'Oncethe door is closed on remote and left on bridgeoperation, whenanybodythen thevisualand audiblealarms will operatefor the periodoltime that the dooris open. Localoperation.The door should be kept in the closedmode. When passingthroughit the beoperatedto openthe door fully. The tperator shouldthenpass ttgoughaia ctosethedor handleon the otherside of the door. SeeM Notice???
172' Draw the fire main and indicate aII main isolatingvalves. 173' Explain what you would do before going UMS. How doesthe patrol alarmwork? Checkbilgesaredry. check all weightedsoundingpipe cocks are in place. check all alarmsare clearedand that none aregagged. All variouscompartmentsi.e. purifier room nte ators areclosed. All fire zonesareactivated. Oil mist detectoroperating. All weldingor burning equipment isolated. Engineroom left tidy. All equipment(loose)batteneddown in caseof badweather. TestUMS alarm. Inform bridge. Thepatrol alarmis a systemto protect the duty engineerwhilst he is alonein theengineroon His rounds' Upon entering the engine room, tr ui alarmgoingoffwhen UMS,thepatrolm active'Thepatrolman needsto be resetevery l0 mins,if not an alarmwill soundintheeng: this alarmis not answered,then after 27 mins the Engineers alarmwill be sounded. 174. How is the purifier motor connectedto the pump? Theoil pumpis connectedto the purifier by meansof a link, held togetherby a shearpin,tht wasto foul the internalsof the pump causingit to jam, the pin would shearcausingminimal motoris connectedto the horizontal shaft of the purifier bya centrifugal clutch. Thehorizon wonn getr, which engageswith a bevel gearto drive the vertical shaftandbowl arrangement pump is connectedto the horizontal shaft via the shearpin. 175' What safetyfeaturedoes a turbine have in the event of lossof power? Theturbineis safeguardedin way of lubrication in the eventof a lossof power(blackout) by controllubricatingoil via an orifice. The tank abovethe turbine/gearboi i, constantly filling pumpanddraininginto the bearingsof the turbine/gearbox. So in the eventof a fail're there supplyof oil to enablethe engineto be broughtto restsafelywithout incgrringanydamage. 176. What do you look for in fuel tanks? In fuel tanksyou would look for water, which may indicateleaking heatingcoils,badsupplyr watercomingbackdown the vent pipe. (BRAIR) 177. why are the sliding feet at the front of a turbine?
*:113ff
fr:L::ioned
onthefrontof thet'rbineto allowforthermal expansion astheca
178.
How and why do you sootblow? The sootblowerusessteamor compressed air to blow awaysootor any otherproductsof c the surfacesof the boiler tubes. Sootblowingat regulariniervalswill prevent a build up ol the heat transferthusimprovingthe thermaliffiri.nry of theboiler. Failure to sootblow c build up of sootin the uptakeswith a resultingdangerof fire.
179'
Why do you drain the air bottlesand what arethe dangersif they are not drained? The air bottlesshouldbe drainedregularlyto removewaterasthe build up of water in the I to faulty startingof the engineaswell asthedangers of corrosionto the internalsof the air carryover from the compressor mixing with thewatercanalsocauseproblemswith the aut other componentsin the startingair system.Problemscouldalsooccur in the control air s5
180'
How do you know if an air start valveis leakingexhaustgasesback through the air start line? What are the dangers? If an air startvalve wasleaking,this wouldbeindicatedby hightemperatue in the starting causing paint on the outsideof thepipeto burnanddiscotouranapeel. The leaking valve < noisy and be heardby the watchkeeper:Thedangerof a leakingair startvalve is that of a s explosion' If a valve is leakingtheengineshouldbestoppedimmediately andthe valve cha
181.
Define safeand hazardouszoneswith regardto a tanker.
182.
Where do you usebled steam?
183.
What is O.D.M.E?
184'
What precautionsmust you takewhen recharginga dry powder fire extinguisher?
185'
With referenceto an asternturbine nozzle---(a) What is the blowdownratio? (b) Whar pressure? (c) How is the high pressuresteamexhausted to vacuumconditions?.
186'
How is the air in the scavenge manifold preventedfrom flowing back through the cool, piston is on the downward stroke?
187'
Describe how you would withdraw a burner/nozzleforcleaning.
188.
What is the pur?oseof the vortex plate?.
189'
With regard to a bilge system,what is the meaningof the B/5 rule?. Provision is to be madein everyvesselto preventthefloodingof anywatertight compartmer bilge suctionpipe in the eventof thepipe6eingsevered o, duirugedby collision or gro'ndir watertight compartment-Whereanypart of ru.tr a pipeis situatein"*rr. to the side of the sh the midship breadthof the shipmeasured at thelevliof the deepestsubdivisionload water I duct keel' a non-returnvalve shallbe fitted to thepipein the*uL, tight compartmentcontai: end of the pipe.
190'
With regard to gascarriers, describethe operationof the gas bumer. Explain boit off inspection?
l9l'
Ifr when openinga valve, water hammeroccuris.What shouldbe done? When steamlinesareshutdownit is possible,fromvariouscauses, for themto fill with w allowed to entera line filled with water,thesteamstartsto move the waterdown the line. contact with the watereventuallycondenses anda vacuumis thenformedcausingthe watr back at a very high velocity.Thewatertravellingat thathighvelocity returnsto the valve , been openedandstrikesit with a veryhearybl;, oftenfracn:ring the valve.If the valve f disastrousresultsmay occur'with the risk of lossof life. ln order to preventwater hammer open up the drain connections on the steamline whichis beingbroughtinto use.The water be completelydrainedsothatit leavesthe line clear.Thesteamvalvi maythen be very slil (cracked open)so that the line canbeheatedandit's temperature broughtup to near worki: Any condensateformedduringthis perioddrainsout of thedrainsprruiourl-y op"rr"d. As tl temperaturerisesandthenoisefrom the drainschanges to thatof a steambllwthe steamp line can be slowly increased by openingthe steamvalvefirther. Eventuallythe drains may the steamvalve hasbeenfully opened.
192.
what is the pur?oseof taking crankshaftdeflections? The purposeof taking crankshaftdeflectionsis to checkfor crankshaft misalignment. They shouldbe takenat regularintervalsor whendamage to the ryuung gr*]propeller, sh stnrcture is suspected. Theyshouldalsobetakenprigt ti entering dry d;ck when work on t is to be carriedout.Theyshouldthenbetakenugin whenleaving dry dock r il:t*|:flngs
'
The crankshaftdeflectionsshouldbetakenwith theengineat the sametemperatureand the loading as nearaspossibleto the sameconditionseachtime. Misalignment occursdueto wearof themainbearings andfrom distortionof the enginebe< possibly from d*ug-. to the ship'sstnrcture.It canbe detected by measuringthe deflection webs for eachunit of the engine.If misalignment existsthecranlcwebswill openand close engine is rotated'The deflectionsaremeasured by meansof a clock or dial gaugefitted betr webs at a point in line with theoutsideof thejournalfurthestfrom the pin. A spring loaded holds the dial gaugein position. 193.
What is the function of the stuffing box?
t94.
where and what is the functionof the bedplate?
195'
What would happenif the exhaustvalveof oneunit is blocked?
196'
what fype of cargo did you carry on LPG shipsandwhat are the
temperatures?
lg7 '
What type of cargo did you carry on LNG shipsandwhat are the
temperatures?
198'
Did you have plastic pipeson your sewageplant? what is the problem if there is no flr through them and what wouldyou do?
199'
How do you put a piston on a slowspeedenginebackinto the engine,with regards to li
200'
What could be the reasonfor the pistonstickingwhenputting it
201'
what is the TBN rating asapptiedto Lub oil? statesuitable TBN ratings for a Lub o a medium speedand a slowspeedengine?
back?
202' Describehow youwould changepiston rings. what would you be looking for? 203. Why would an air compressorrun hot? 204. what actionwourdyou take if an air compressor ran hot? 205. How do you testsmokealarms? 206. what actionwourdyou take if a purifier rost its sear? 247, How do you know if a purifier is up to speed? 208'
How do you controlthe steamflow through a steam heating coil? By the inlet valve r valve. Give reasonswhy.
209' In someinstancescleansingagentsare used to clean the bilges. what type of cleaninl and what are their l. Advantages2. Disadvantages. 209' How oftenshouldthe emergencygenerator and the emeqgencyelectricalsystem be tr The recommended time for the iest ".rot 210' when operatingin the uMS mode,some classification societieshave regulationsfor t Alarms to be fitted. Thesetypesare collectedinto two groups. what are thesegroup 212-
what is the purposeof your rore as a watchkeeper?
213' what couldbe the problemif the temperature of a cylinder gradually increasesove* 214' what detergentsdo you usewhen cleaning the floorplates on your ship? How do they they affect separationin the OWS? 215' The engineis racingand slowing- A white lnazecanbe seen for about l0 milesbehind what is the probremandwhat woutdyou do about it? 216' ll"r:ifr
in the boileris higher than the gauge glass. what
is the probtem and what
217' when pre sailingsteeringgear checks what special attention , shouldbe r rudder1:"ry:og^out bearing? 218' Namethe parts of an ESD2 boiler and explain the direction
of steamflow.
219' It is proposedto blow downa high pressure water tube boiler, what is the first procedr process? 220' what is the functionof the enginegovernor? Exptain
its operation.
221' rn a slow speedengine,any dirt etc, resutting from blowpast is collectedin the scaveng( thereforedoesnot enterthe crankcase.wnat happens to blowouts in a trunk piston er stepsare taken to preventdamageto the engio" J"".rrring? 222. what is the purposeof a sootblower?Exprain its operation. 223. what safetydevicesare fitted to an air compressor?
224. What is the differencebetweena slow acfing and a fast acting detergent? 225. How doesa coalescer work? 226. How canyou tell the differencebetweena coalescerand a filter just by looking at it? 227. What is meantby s6steady flow, and ..eddy flow *? 228. Wheredo the drainsfrom a wash basin in the engine room lead to? 229. What is meantby a ,,critical speed"? 230. Explain howa turbo chargersurges. what is the surge tine? 232'
If oil floatson top and the water will sink to the bottom in a bilge well, canrtyou just " -- - pu rslowlyseeingasthe suctionis in the water?
233'
What typeof pump is the OWS bilge pump? What is the rotor madeoI? What is the st
