Oral Ques and Ans

ORALQUESTIONSANDANSWERS 1.Crudeoilwashing(COW)iswashingouttheresiduefromthetanksof 1.Crudeoilwashing(COW)iswashingoutthe residuefromthetanksofanoilt anoilt ankerusingthecrudeoilcargoitself,after ankerusingthecrude oilcargoitself,afterthecargotankshavebeen thecargotankshavebeenemptied. emptied. CrudeOilispumpedbackandpreheatedinthe CrudeOilispumpedb ackandpreheatedinthesloptanks,thenspr...a sloptanks,thenspr...ayedback yedback viahighpressurenozzlesinthecargotankso viahighpressurenozz lesinthecargotanksontothewallsofthetan ntothewallsofthetank.Dueto k.Dueto thestickynatureofthecrudeoil,theoilc thestickynatureof thecrudeoil,theoilclingstothetankwalls, lingstothetankwalls,andsuch andsuch oiladdstothecargoremainingonboard(theROB).ByCOWingthetanks,theamou ntofROBissignificantlyreduced,andwitht ntofROBissignifica ntlyreduced,andwiththecurrenthighcostofo hecurrenthighcostofoil,thef il,thef inancialsavingsaresignificant,bothforthe inancialsavingsares ignificant,bothfortheCharterersandtheShipo CharterersandtheShipowner.If wner.If thecargoROBisdeemedasliquidandpumpablethentheChartererscanclaimfrom theownerforanycargolossfornormallybetw theownerforanycarg olossfornormallybetween0.3%upto0.5%.Itr een0.3%upto0.5%.Itreplacedt eplacedt heloadontopandseawaterwashingsystems,b heloadontopandsea waterwashingsystems,bothofwhichinvolveddis othofwhichinvolveddischarging charging oil-contaminatedwaterintothesea.MARPOL73 oil-contaminatedwater intothesea.MARPOL73/78madethismandatorye /78madethismandatoryequipment quipment foroiltankersof20,000tonsorgreaterdeadweight. 2.Selectivecatalyticreduction(SCR)isamea 2.Selectivecatalytic reduction(SCR)isameansofconvertingnitrogen nsofconvertingnitrogenoxides, oxides, alsoreferredtoasNOxwiththeaidofacata alsoreferredtoasNO xwiththeaidofacatalystintodiatomicnitrog lystintodiatomicnitrogen,N2,a en,N2,a ndwater,H2O.Agaseousreductant,typically ndwater,H2O.Agaseo usreductant,typicallyanhydrousammonia,aqueou anhydrousammonia,aqueousammonia sammonia orurea,isaddedtoastreamofflueorexha orurea,isaddedto astreamofflueorexhaustgasandisabsorbedo ustgasandisabsorbedontoacat ntoacat alyst.Carbondioxide,CO2isareactionprodu alyst.Carbondioxide, CO2isareactionproductwhenureaisusedast ctwhenureaisusedasthereduct hereduct ant.Ammoniaslipisanindustrytermforammo ant.Ammoniaslipisa nindustrytermforammoniapassingthroughtheS niapassingthroughtheSCRun-rea CRun-rea cted.Thisoccurswhenammoniais:overinject cted.Thisoccurswhen ammoniais:overinjectedintogasstream,tempe edintogasstream,temperaturesa raturesa retoolowforammoniatoreact,orcatalysth retoolowforammonia toreact,orcatalysthasdegradedcatalysteg. asdegradedcatalysteg.titanium titanium oxide. 3.Remotedetectionofoilspills IonicsAgarEnvironmentalhaslaunchedLeakwis IonicsAgarEnvironmen talhaslaunchedLeakwiseWL,anewwirelessoil eWL,anewwirelessoilsheende sheende tectorandoilbuild-upmonitorwhichusesOrb tectorandoilbuild-u pmonitorwhichusesOrbcommsatellitecommunicat commsatellitecommunicationandc ionandc ellularnetworkstoalertoperatorsofoillea ellularnetworkstoal ertoperatorsofoilleaksandspills.Designedf ksandspills.Designedforinstal orinstal lationonshorenearterminalstoragetanksand lationonshorenearte rminalstoragetanksandpipelinesandatseaclo pipelinesandatseaclosetotan setotan kerjettiesandoffshoretankerbuoys,theLea kerjettiesandoffsho retankerbuoys,theLeakwiseWLsensorscandete kwiseWLsensorscandetectthepr ctthepr esenceofaslittleas0.3mmofoilonwater esenceofaslittleas 0.3mmofoilonwaterandmonitoritsbuild-up. andmonitoritsbuild-up.Thefloa Thefloa tingsensorsinLeakwiseWLusethelatesttec tingsensorsinLeakwi seWLusethelatesttechnologyofhigh-frequency hnologyofhigh-frequencyelectrom electrom agneticenergyabsorptionandareunaffectedb agneticenergyabsorpt ionandareunaffectedbydirtoroilcoatingor ydirtoroilcoatingorbyhanges byhanges inwaterlevel,salinityandtemperature.Thi inwaterlevel,salin ityandtemperature.Thisenablesreliableoperat senablesreliableoperationwith ionwith nofalsealarmandverylowmaintenancecosts, nofalsealarmandver ylowmaintenancecosts,accordingtothemanufac accordingtothemanufacturer.Th turer.Th eLeakwiseoffshoredetectorismountedonas eLeakwiseoffshorede tectorismountedonastablewave-riderbuoyand tablewave-riderbuoyandcontains contains asolarpanelwithrechargeablebattery,digi asolarpanelwithre chargeablebattery,digitalsignalprocessor,tra talsignalprocessor,transceiver nsceiver forthebidirectionaldatalinkandantennaef forthebidirectional datalinkandantennaeforsatelliteandcellular orsatelliteandcellularcommunic communic ations. 4.Whatallcertificatetobecarriedaccordin 4.Whatallcertificat etobecarriedaccordingtoannex6? gtoannex6?  InternationalAirPollutionPreventionCe InternationalAir PollutionPreventionCertificate.OurAdministra rtificate.OurAdministrationDGS tionDGS hippinghasnotyetratifiedthesame,therefo hippinghasnotyetra tifiedthesame,therefore,forIndianFlagVesse re,forIndianFlagVesselstheyi lstheyi ssueStatementofCompliance(SOC).Alsocontr ssueStatementofComp liance(SOC).Alsocontrolofemissionsfromship olofemissionsfromshipandcert andcert ificateforVolatileOrganicCompounds. 5.Harmonizedsurveyorhowcertificationofs 5.Harmonizedsurveyo rhowcertificationofshipisharmonized-Harmo hipisharmonized-Harmonization nization ofcertificationmeansallthesurveysarenor ofcertificationmeans allthesurveysarenormallycarriedoutinone mallycarriedoutinonegowithin gowithin thewindowperiod.ThiswilleasetheOwners thewindowperiod.Th iswilleasetheOwnerstocompleteallthesurve tocompleteallthesurveysindry ysindry dockorduringlayupofthevessel.Alsoany dockorduringlayup ofthevessel.Alsoanyrecommendationarisingd recommendationarisingduringthe uringthe surveyscanbeeasilydealtwith.Harmonizat surveyscanbeeasily dealtwith.Harmonizationofcertificatenormal ionofcertificatenormallydoned lydoned uringtherenewalsurveys(everyfiveyearly) 6.Containercapacity-howmuchloadacontainercancarry Normally20cbmor40cbm 7.Whatisdewatering? Processtoremovewaterdropletsfromairsayscavengeair.Thisisnor Processtoremovewaterdropletsfromairsay scavengeair.Thisisnormallyach mallyach ievedbymanystagesfinefiltering. ievedbymanystagesf inefiltering.    8.Howtoweld16mmplatewith8mmplate

Onesidetobeflushedwiththickplatewhileothersideofthethickplatetob eshamperedat1:3ratiotomatchwith8mmplate. 9.Whatisthepurposeoftopsidetanksinbulkcarriers? Topsidetanksareusedonlywhenshipisloadedwithhighdensitycargoes,like steelsheets,rollsetc,,inthatcasecentreofgravitygmovestoolowtomak eextremelylargeGM,(stiffship)whichinturncanbreakshipinanybadweath er,toraiseGuptheTSTisfilledwithwater,otherdesignofbulkcarriersar ethereinwhichtopholdsofsmallersizesinmidoftwoholdsaretheretoloa dsamecargoandthusadjustingGM. 10.Whygovernorspringisconical? Ingovernormeasuredparameterisspeedandmeasuredbytheflyweights.Flyweigh tssensethespeedbycentrifugalforce,soC.Fismw2r(wherewisangularvelo city),sosincethespeedismeasuredinpowerofsquare,thecorrectingaction shouldalsobeinpowerofsquare.Inconicalspringthestiffnessalsobehaves inpowerofsquarepattern(stiffness=force/deflection,sowhenuapplyaunit force,thedeflectionisinpowerofsquare).Sothespringsareconical. 11.Whatdoes3/8or¾meansinthreadnomenclature? ?3/8or¾meansthenominalODofthebolt.ForCoursethreadstheTPIwillbe16an dforfinethreadstheTPIwillbe20.ActuallythatsaccordingtotheAmericans tandards.Metricstandardsdefineitineg.M10*1.5where,10isthenominald iameterand1.5isthepitch.IfPitchisnotmentioned,thenwetakeitasthat threadisbelongingtothecoursegroup. 12.Whathappenswhenalltheflywheelmarkingsaresomehowerasedandhowwill youcheckthetimings,tappetsetc? Thecamshaftwillgiveabriefidearegardingpositionoftheengine.Therewil lbetwounitswhichwillbeinTDCsojustrotatethepushrodtoseewhichone isthereinthepowerstrokebecausetheunitwhichwillbeinTDC,thepushro dswillberotatingfreelyandthuswecancheckthetappetofthatengine.for timingalsowehavetoseethecampositionandmarkingonthepumpplungerbut itisverydifficulttoknowthevalueexactlywhenfuelinjectionisstartinga ndstoppingasthereisnomarkingintheflywheel. 13.PIPESCHEDULE PipeScheduleisthetermusedtodescribethethicknessofapipe.Theoutside diameterofapipeisthesameforallSchedulesinaparticularnominalpipedi ameter.StandardpipeschedulesorpipessizesasgivenbyANSI/ASMEB36.10Ma ndAPI5L.Theseschedulenumbersbeararelationtothepressureratingofthe piping.ThereareelevenSchedulesrangingfromthelowestat5through10,20, 30,40,60,80,100,120,140toscheduleNo.160.Regardlessofschedulenumber ,pipesofaparticularsizeallhavethesameoutsidediameter(notwithstandin gmanufacturingtolerances).Astheschedulenumberincreases,thewallthicknes sincreases,andtheactualboreisreduced.Forexample:A100mmSchedule40p ipehasanoutsidediameterof114.30mm,awallthicknessof6.02mm,givinga boreof102.26mm.A100mmSchedule80pipehasanoutsidediameterof114.30m m,awallthicknessof8.56mm,givingaboreof97.18mm.Theschedulenumberi sdefinedastheapproximatevalueoftheexpression:ScheduleNumber=(1,000)( P/S)Where,P=theinternalworkingpressure,psigS=theallowablestress(psi) forthematerialofconstructionattheconditionsofuse.Forexample,thesche dulenumberofordinarysteelpipehavinganallowablestressof10,000psifor useataworkingpressureof350psigwouldbe:ScheduleNumber=(1,000)(350/10 ,000)=35(approx.40)MethodforDeterminingScheduleMeasuretheinsidediame teranddivideitbythewallthickness.(Inches)R=ID/ThicknessPipeSchedule RSchedule3040-50Schedule4029-39Schedule6025-29Schedule8020-23Schedu le10016-18Schedule12013-15Schedule14011-13Schedule1609-11 14.AsperMarpolannexIIwhatiswaterperformancetest? Procedure-fillcargotankwithwatertoadepthnecessarytocarryoutnormale ndofunloadingprocedure.cargotankpumpedandstrippedwithassociatedpiping inaccordancewithshipsapprovedmanual.Collectwaterremainingincargotank &pipingincalibratedcontainerformeasurement.Residueshouldbecollectedf rom-cargotanksuctionanditsvicinity,anyentrappedareaincargotankbott om,lowpointdrainofcargopump,alllowpointdraininpipinguptomanifoldv

alve.Totalquantitycollectedabovedeterminesstrippingquantityforcargotan k.Ifmorethanonetankisusingpumpandpipingthenalldrainedanddistribut edamongstthetankifmentionedinapprovedmanual.Conditionoftesting-trim (minimum)bysternandlist<1tofacilitateproperdrainageatsuctionpoint.an dduringtestbackpressuremaintainedatminimum1baratcargotankunloading manifold. 15.Whatdoes?15W40denote? Here40isSAEnumber.SAEnumberlikeSAE10,SAE20correspondstothathavin gkinematicviscousityat100°C.LikewiseWdenotesthewintergradeforcoldstar t.ThusSAE15W40denotesthatthelubeoilofthisgradehaskinematicviscousi tyof40cstat100°Canditswintergradeis15Wie,thecrankingandpumpabili tyofthislubeoilgradehaspassedtestsof20Wand15Wbutfailedtestof10W atbelowzerotemperatures. 16.MOBmarker? TheLifebuoyscomeintwosizestocoverallSOLASrequirements.Oneweighing2. 5kg,thestandard,andoneweighing4.5kgtocomplywithSOLAS-74ChapterIII, Reg.31.1.7whichstatesthattooperatethequickreleasearrangementforself -activatedsmokeorlight,thelifebuoyshouldweighmin.4kg.(Bridgewing:Sm okeandlight). dayandnightsignalattachedtoLifebuoyandusedinemergencytomarkposition ofmanoverboardprovides15minutesofdenseorangesmokefarexceedsSOLASre quirementsof2hoursat2candelaforlightoutputanddurationsafetouseon petroloroilcoveredwaterlithiumbatterysealedforlife-noannualreplacem entautomaticormanualdeploymentuniversalstainlesssteelmountingbrackette stedtosurvivea60mdropintowater(SOLAS30m)idealforuseonshipsorrigs withhighfreeboard360degreesall-aroundsignallight. 17.Whatissquattingeffect? Thesquateffectisthehydrodynamicphenomenonbywhichavesselmovingquickly throughshallowwatercreatesanareaofloweredpressureunderitsbottomthat causestheshiptosquatlowerinthewaterthanwouldotherwisebeexpected.Thi sisduetoareductioninbuoyancycausedbyadownwardhydrodynamicforcecrea tedbyflow-inducedpressures.Itiscausedbysimilarforcesasliftinaircraf t,exceptthatthelowpressureareaisbeneaththehull.Itcanleadtounexpec tedgroundingsandhandlingdifficulties. Thisphenomenoniscausedbyhydrodynamiceffectsbetweenthehulloftheshipa ndtheseafloor.Squateffectisapproximatelyproportionaltothesquareofth espeedoftheship.Thus,byreducingspeedbyhalf,thesquateffectisreduce dbyafactoroffour.Squateffectisusuallyfeltmorewhenthedepth/draftra tioislessthanfourorwhensailingclosetoabank. Thephenomenoniscausedwhenwaterthatshouldnormallyflowunderthehullenc ountersresistanceduetothecloseproximityofthehulltotheseabed.Thisca usesthewatertomovefaster,especiallyunderthebowoftheship,creatinga low-pressurearea.Thiscounteractstheforceofbuoyancy,causingthevesselto diptowardsthebow.Thereducedpressureonthebottomoftheboatsuckstheb oatslightlydownwarduntiltheincreaseddisplacementcounter?actstheforcege neratedbythereducedpressure. 18.Hypermistsystems? ?NewIMORequirementsTheIMOrequiresallshipsconstructedonandafterJuly1 ,2002toinstallwater-basedlocalfireextinguishingsystemsinmachineryspac esaccommodatingmachinerywithaparticularlyhighriskoffire(mainengine,D /Gengine,boiler,incinerator,F.O.purifierandI.G.G.)withtheaimofexting uishingorsuppressingfiresintheirearlystages.Thisnewrulewasestablishe dinrecognitionoftheimportanceofexitnguishingorsuppressingfireswhilet heywerestillsmall,afteranalyzingmanyon-boardfireincidentsfromallover theworld.Thisideaaroseinresponsetosituationsinwhichpromptoperation wasdifficultwithprevioussystems(especiallyCO2fireextinguishingsystems), becausethecrewssafetyhadtobeconfirmedbeforedischargingtheextinguishan t,whichenabledfirestoexpand.

TheHYPERMISTemploysspeciallydevelopednozzlesoperatingathighpressure(app rox.5MPa)togeneratesuperfineparticlesofmistrangingfrom30to80micron sindiameter.Whensprayedonafire,themistofferscompoundeffects:itabso rbsradiantheatfromthefire,createsashield,reducesthetemperatureofthe fireareabyevaporatinguponcontactwiththeflameanddepletestheoxygen,t herebyextinguishingorsuppressingthefire. Maintenanceincludesblowingthroughlineswithair,operationofpumpandprope rsolenoidoperation. 19.UnderwhichclauseinISMSafetyManagementSystemisthere? (PartA:clause1.4,partAisIMPLEMENTATIONandpartBiscertificationandve rification) 20.WhatmaterialsareusedinLPGtanksconstruction? INVAR:36%nickelsteelwith64%ironor9%nickelsteelforhighertemperature . 21.Actionstobetakenduringboileruptakefire? Boileruptakefireisbecauseofwetsootdepositedduringlowsteamingandals oduringuptakefiredonotcarryoutsootblowreducetheloadandstoptheeng ine,coverthem/et/cwiththecanvassothatnoairissupplied. 22.HowmuchisNeedlevvlift?? Gene?rally1mmmaximumfor320barliftingpre ssure. 23.Boilercorrosionhowithappensandhowtoprevent? Themostcommoncausesofcorrosionaredissolvedgases(primarilyoxygenandca rbondioxide),under-depositattack,lowpH,andattackofareasweakenedbymec hanicalstress,leadingtostressandfatiguecrackingandpittingcorrosion:sc alessuchascalciumandmagnesiumsalts.Manycorrosionproblemsoccurintheho ttestareasoftheboiler-thewaterwall,screen,andsuperheatertubes.Otherc ommonproblemareasincludedeaerators,feedwaterheaters,andeconomizers. Prevention: maintenanceofproperpHandalkalinitylevelsbetween8.5and9.5controlofox ygenandboilerfeedwatercontamination(lessthan7ppboxygenfora900psig boiler)reductionofmechanicalstressesoperationwithindesignspecifications, especiallyfortemperatureandpressureproperprecautionsduringstart-upand shutdowneffectivemonitoringandcontrol24.Accumulationofpressuretestin boiler? ClassificationSocietiesrequirethatthatwheninitiallyfittedtoboilerssafe tyvalvesmustbesubjectedtoanaccumulationofpressuretesttoensuretheva lvesareofthecorrectdischargecapacityfortheboiler.Toconductsuchates t,allfeedinletsandsteamoutletstoandfromtheboilermustbeclosedandm aximumfiringloadachieved.Accumulationofpressuremustthennotexceed10%o fworkingpressure.Durationoftestisnottoexceed15minutesforcylindrical boilersand7minutesforwatertubeboilers. 25.Howtoreducemaintenanceinexhaustvalve? Goodqualityfuelusage,VITadjustment,avoidrunningengineonlowload,chec kfuelinjectionsystem,goodscavenging,maintainingcoolingwatertemp,check rotationofexhaustv/v. 26.Refrigerationgaseshowitsclassifiedaccordingtoenvironmenthazard? Ozonedepletionpotential-maxR11,forR22is0.05andglobalwarmingpotential -maxisR11.andR22is0.365 27.Howinductionmotorworks?  Aninductionmotororasynchronousmotorisatypeofalternatingcurrentmotor wherepowerissuppliedtotherotorbymeansofelectromagneticinduction.Ane lectricmotorturnsbecauseofmagneticforceexertedbetweenastationaryelect romagnetcalledthestatorandarotatingelectromagnetcalledtherotor.Inan

inductionmotor,thecurrentisinducedintherotorwithoutcontactsbythemag neticfieldofthestator,throughelectromagneticinduction.Thecurrentinthe primarysidecreatesanelectromagneticfieldwhichinteractswiththeelectrom agneticfieldofthesecondarysidetoproducearesultanttorque,therebytrans formingtheelectricalenergyintomechanicalenergy.Theinductionmotordoesn othaveanypermanentmagnetsontherotor;instead,acurrentisinducedinthe rotor.Thestatorwindingsarearrangedaroundtherotorsothatwhenenergized withapolyphasesupplytheycreatearotatingmagneticfieldpatternwhichswe epspasttherotor.Thischangingmagneticfieldpatterninducescurrentinthe rotorconductors.Whencurrentflowsthroughaconductoramagneticfieldispro ducedaroundtheconductor.Thiscurrentinteractswiththerotatingmagneticf ieldcreatedbythestatorandineffectcausesarotationalmotionontherotor . 28.Contactorsmaintenanceonstarterwhatisthematerialofcontactor? Checkforloose,missing,brokencontactorsCleaningandcheckingcontactsurfac esforimproperwearordiscolorationRemoveoxidesfromfacesusingfinefiles Maincontactsarehighconductivitycopperbecausetheywillnotheatupdueto lowerresistanceandarcingcontactsaremadeofsinteredsilvertungstenoroth ermaterialswhichdontweldathightemperatures. 29.HowsignaliscarriedtoECRfromrpmindicator?? Magneticpickupsendssignaltotransducer.Anoutputcomi ngfromatransducerisfiltered,signalconditionedandchopped.Finallyitis convertedintosquarewaves.ThesquarewaveispassedthroughPhaseLockLoopm ultipliers.Thisoutputisgatedbyaprecisetimebasegeneratedthroughpiezo crystalsandthencounted.ThesecountsaredisplayedonbrightLED's.It'snoth ingbutR.P.M.withaccuracyof±1RPM. 30.Cranejibiscrackedhowurgoingtoweld?? Arrestcrackbydrillingholesatbothendsandweldsupp ortingplateatthebackandthencarryoutweldingonthecrack. 31.Juniorengineerboxedbackthepurifieraftercleaningthenitsfoundvibrat ingprobablecauses? bowlmaynotbecleanedproperly,lockringnottighteningproperly,bowledasse mbledwithwrongparts,gearcanbeindamagedcondition,bowlspringsnotfitte dcorrectly,topbearingspringsdamaged,discsnotproperlyassembledortighte ned,someexternaltoolleftinside32.Insulationofmotorisfoundtobe0.5 megaohmswhatwecandotobringbacktheinsulation? DisconnectmotorCleanwindingsDrythemotorbyheatinglampCheckvisuallyfor anywiresbrokenPutfastdryingvarnishTestinsulation33.ProcedureforCWT test? 1.Fillthesamplecuptothe25mlmarkwithsample. 2.SlidetheopenendofthevalveassemblyoverthetaperedtipoftheTitret1 sothatitfitssnuglytothereferenceline. 3.SnapthetipoftheTitretatthescoremark. 4.LiftthecontrolbarandinserttheTitretassemblyintothebodyoftheTitr ettor2. 5.Withthetipofthevalveassemblyimmersedinthesample,pressthecontrol barfirmly,butbriefly,topullinasmallamountofsample.Thecontentswill turnagreencolor. CAUTION:Donotpressthecontrolbarunlessthetipofthevalveassemblyisim mersedbelowthesurfaceoftheliquid. 6.Pressthecontrolbaragainbrieflytoallowanothersmallamountofsamplet obedrawnintotheampoule. 7.Aftereachaddition,rocktheentireassemblytomixthecontentsoftheampo ule.WatchforacolorchangeFROMGREENTOBRIGHTORANGE. NOTE:Immediatelybeforethecontentsturnbrightorange,theywillbrieflyturn blue.Makefurtheradditionswithcare. 8.Repeatsteps6and7untilapermanentcolorchangeoccurs. 9.WhenthecoloroftheliquidintheampoulechangestoBRIGHTORANGE,remove

theampoulefromtheTitrettor.Holdtheampouleinaverticalpositionandcare fullyreadthetestresultonthescaleoppositetheliquidlevel.Seethefollo wingcharttoobtainresultsinppmproduct. SatisfactoryRangesScale ProductScaleppmproduct LIQUIDEWT1.2-1.8310,0000-15000 ^MAXIGARD11.6-3.019,000-36,000 'DEWT®NC.5-5.03,000-4,300 Titrateampule:>85%DelonizedWater,<10%Sulfuricacid,5%Cericsulfate Valveassembly:>95%DiethyleneGlycol,<1.5%1.10-Phenanthroline,<1.5%Delon izedwater Alternatemethod:Takea5mlsampleofcoolingwateranddiluteitwith45mlof distlledwaterandadd2dropsofpotasiumcromateindicatorandtitratewiths uphatebasedreagenttoobtainacolourchange. 34.Whatisascavengelimiter? The"scavengeairfuellimiter"isanintegralpartofanelectronicgovernora nditlimitsthefuelaccordingtothepressuremeasuredonthescavengingairr eceiverbyatransducer.Thelimitercurveissetaccordingtoenginemakersspe cification.Duringstartingwhenthescavengeairpressureislowitlimitsfuel . 35.Whatissingingofpropeller? Iftipclearanceisincreased,thentheaftendvibrationstartsandnoisecomes duetolargedistancebetweensternandpropellertip.Thisisknownassinging ofpropeller. 36.Whatisinjectiondelay? Injerktypepumpwhenspillportorspillvalveandsuctionportorsuctionval vebothgetclosed,atthattimeinjectionshouldstartpractically,butdueto inertiaoffluidandothermovingpartsofinjector,injectiondoesnotstartim mediately,althoughoilisconsideredincompressiblebutitgetscompressedslig htly,andatthesametimethehighpresspipegetsanexpansionallwayandaft erthatinjectionstarts.Thispotentialenergygetsreleasedduringtermination ofinjection. 37.Whatisproportionalcontrolandoffsetcontrol? Inproportionalcontroltheoutputofcontrollerisproportionaltothedeviatio nhenceforoutputtooccuradeviationhastobethereie,anoffsethastobe thereinproportionalcontrol.Whileinintegralcontroltherateofchangeofo utputofcontrollerisproportionaltothedeviationsoitisabletominimizet heoffset. 38.WhatisSkineffect? Skineffectisthetendencyofaccurrenttodistributeitselfwithinaconducto rwiththecurrentdensitiesbeinglargestnearthesurface.Itcausestheeffec tiveresistanceoftheconductortoincreaseathigherfrequencieswheretheski ndepthissmallerthusreducingeffectivecrosssectionoftheconductor. 39.WhatisaDieselSwitch?? Chan?geoverfrompreheatedHFOtocoldMDO/MGOandv iceversarepresentsariskoffuelpumpstickingorseizureduetotheverysma llclearancesinthefuelpump.TheDieselSwitchisabletodothechangeoveri nacontrolledwaysothatrapidtemperaturedeviationsareavoided.Thistenden cyislikelytospreadandwill,forinstance,beintroducedinEuropeanharbour sfrom1January,2010.Thismeansmorefrequentchangeovers.Aswefindthatth echangeoverbetweenHFOanddistillatefuelscangiveproblemsforthefuelequ ipment,theprocesswillneedahighdegreeofautomationtoavoidincidents.MA NDieselnowofferstheDieselSwitch,whichensuresthenecessarytheflexibili tyandsafetywhenchangingbetweenHFOandMDO/MGO. TheprincipleoftheDieselSwitch-TodayMANDieselrecommendstoreducethelo adto25-40%tocontrolthechangeover.TheDieselSwitchensuresacontrolleda ndsafechangeoverindependentoftheengineload.TheDieselSwitchoperateson acombinationofthetemperatureattheengineandthetime.Ifthefueltemper atureattheengineinletexceeds2degrees/minutetheDieselSwitchwillgivea nalarmandputtheprocessonhold.TheprocesswillbeloggedintheDieselSw

itchsothatitcanbeusedasdocumentationtoportauthoritiesafterthechang eover. TheDieselSwitchoffers: TouchscreencontrolpanelControlhandleforthechangeoverSafetyDatalog gingChangeovervalveMagneticcouplingIntegratedsensorforactualpositio nIntegratedsensorsforendpositionsIntegratedconnectionboxManualoverr ideControllinganMGOcoolerorchillerDataloggingoftemperaturesandpres suresRemoteoperationwithsecondtouchscreen 40.Howaluminumiswelded?? ??TIG(TungstenInertGas)welding,alsocal ledaGTAW(GasTungstenArcWelding),isthebestmethodofweldingaluminum.S praythealuminumwithacetoneRinsethealuminuminwater,justincasetheresa nynastyresidue.Thealuminumshouldbecompletelydrybeforewelding.Useast ainlesssteelbrushtoscrubthealuminumshinycleanaroundtheareatobeweld edinonedirectionClampyourworktoaheatsinkmadeofcopperoraluminumPr eheatbeforeweldingupto275degto500degbutoptimumtemp.is350deg.Ifth etungstengetscontaminated,stopweldingandfixit.Whenthetungstengetsto uchestheweldpoolorthefiller,thearcbecomesunstableandtheweldquality goeswaydown.Thebestmethodforfixingthisistoremovethetungsten,layi tonaflatsurfacewiththecontaminatedparthangingovertheedge,hittheco ntaminatedpartofthetungsten(itwillsnaprightoff),reinstallthetungsten ,changethepolaritytoDCEP(directcurrentelectrodepositive),strikeanarc onsomescrapmetaltore-ballthetungsten,switchbacktoAChigh,andyou're readytoweldagain.Fitthepartstogetherastightlyaspossibleleavingnog aps.Thetighterthepiecesarepressedtogetherandthefewerthegaps,theea siertheweldingis.?? ?? Useoneampper.001"ofmaterialthickness.Settheamperageahighertha nthemaximumyouexpecttouseandusethefootpedaltobackitdown.Usepure tungstenforaluminum.Usea1/16"puretungstenfor30to80ampsUsea3/32" puretungstenfor60to130ampsUsea1/8"puretungstenfor100to180ampUse 15to20CFHArgonflow.Useafillerrodsizeequaltothetungstensize.Adju stthetungstentoprojectfromthehoodadistanceroughlyequaltothediamete rofthetungsten.Thearclengthshouldberoughlyequaltothediameterofthe tungsten. 41.Whyduring ruddertestwearedoing35degreeand30degreeandwhynotboth35degree? ?? ??Whenrudderisonstarboard35andthe norderisgiventoport30or35,thevariabledischargepumpgetshugeerrors ignalgivesmaximumpumpingratebutwhenitreaches30inporttheerrorsignal remainsverylessanditismuchlesserthantheerrorbetween0degreeand5d egreebecausewhenat0theerrorismaximumbecausefloatingleverlinkisat9 0°totheradius.Againastheerrorbetween30and35isless,thepumpingratea lsobecomesverylessandathigheranglesthetraveloframismoreforeachde gmovementascomparedtomidposition.Moreoverthefeedbacksystemonthestee ringgeargraduallyreducesthespeedofthegearwithinthelast5degreesof thegearsfullrotation.Ifweputto35thenthehuntinggearwillstarttored ucethepumpstrokeandachievingthisinatimeframeof28secwillnotbeposs ible.Sothetestisdonefrom35°to30°. 42.WhyengineroomvalveliftisD/4? Assumethatvalveislikecylinderandon thetopiscoveredsominimumliftyouwillgetfromequatingthecylinderarea andcircumferenceofthecylinder.AreaofcylinderispD2/4andcircumference ofcylinderispDH.ByequatingboththeequationsyouwillgetD/4.Thatiswhy valveliftisD/4toallowuninterruptedflowwhenthevalveisfullyopen. 43.Whatischockfastening?  Atthetimeofengineinstallation,theengineisallignedandhotres inbondsarepouredinthemouldtotaketheshapeandsolidify.Thisischockf

astening.44.What isproximityeffect??? ?Theproximityeffectincreasestheeff ectiveresistanceandisassociatedwiththemagnetic fieldsoftwoconductorswhichareclosetogether.Ifeachcarriesacurrentin thesamedirection,thehalvesoftheconductorsincloseproximityarecutbym oremagneticfluxthantheremotehalves.Consequentlythecurrentdistribution isnoteventhroughoutthecross-section,agreaterproportionbeingcarriedby theremotehalves.Ifthecurrentsareinoppositedirections,the 43.Whatischockfastening? Atthetimeofengineinstall ation,theengineisallignedandhotresinbondsarepouredinthemouldtotak etheshapeandsolidify.Thisischockfastening. 44.Whatisproximityeffect? ??? Theproximityeffectincreasestheeffectiveresistanceandisassociatedwith themagnetic fieldsoftwoconductorswhichareclosetogether.Ifeachcarriesacurrentin thesamedirection,thehalvesoftheconductorsincloseproximityarecutbym oremagneticfluxthantheremotehalves.Consequentlythecurrentdistribution isnoteventhroughoutthecross-section,agreaterproportionbeingcarriedby theremotehalves.Ifthecurrentsareinoppositedirections,thehalvesinclo seproximitywillcarrythegreaterdensityofcurrent.