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Friday,January04,2013

HullSurveyMethods

Hullsurveymethods,aremeansandprocedurestodetectfailureanddamageatanearlystagetoavoidprematurebreakdown.

Hullsurveymethodsarethereforenotonlycomprehensivemeansofdetectingdeficienciesormonitoringstructuralcondition,butalsoofdefiningschemesforinspectionbetweenthelastoverhaulandbeforetheoccurrenceoffailure.

Meansofdetectionofdefectsandconditionmonitoringareinteralia:

VisualinspectionsNondestructivetesting(NDT)andcalibratingExaminationoftightness,functionandcentreofgravityMeasurementsofthickness,vibration

Schemesofinspectionareperiodicalsurveyrequirementswhichbyvirtueofdesignandoperationalexperienceareenvisagedtodiscoverdeficienciescompletelyandearlyenoughbeforetheymayleadtobreakdown.

1.MEANSOFHULLCONDITIONASSESSMENT

1.1VisualInspection

Amajorpartofhullsurveyingworkiscarriedoutusingvisualskillstoperformtheexaminationsandtoarriveatanopiniononthestateofavesselscondition.Suchvisualexaminationscanbecarriedoutas:

verallinspections,ageneralsightingofavessel'shullcondition,followedbyCloseupexaminationsat

1. locationswherediscontinuities,rupturesordeformationshavebeenfoundand2. certainhullstructuresasstipulatedbyrulesand/orrequirements,forinstanceinwayofcargoareaof

oiltanks.

Examinationofareasofsuspectedcrackandcorrosionconcentration.

Themethodsofvisualinspectionproceduresmaybeappliedasfollows:

1.1.1Visualoverallinspection

ExaminationofexternalhullbodyVisualattentionistobefocusedonthevesselsshapes,linesandcurvesforthedetectionof

unusualdeformation,misalignmentofstructuresalongbottomplating,sideshells,bilgekeels,decks.

Asaresult,permanentdeformationsofmisshapedsectionscanbecausedby:

hoggingsaggingscatteredsetoutlocaldeflectionsfromtheoriginalstructure.

Formeasuringpurposes,awireorapianolinemaybestretchedoutfromforwardtoaftandgaugingderivedfromsuchazerobasis.

Insideinspectionsinholds,tanks,hullparts

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Similarvisualexaminationscanbecarriedoutinsideofcompartments:

Attentionshouldbeconcentratedonthelackofstraightnessofstructures,alongsidelinesfromforwardtoaftandfromporttostarboard,withregardto:

stringersandlongitudinalframes,walls,longitudinalbulkheadsandcorrugations,platforms,transversemembersandbulkheads,frames,brackets,deckbeams,floorsandattachedstiffeners.

Linesand/orstructuresshowingmisalignment,deflection,bucklingorotherdiscontinuities,areanindicationofexistingdefectsrequiringcloseupinspection.

Dockinginspections

Whenavesselisdrydocked,attentionhastobefocusedon:

discoveryofdeformationsand/ordiscontinuitiesalongkeelplates,bottom,andsideplates,bilgekeels,andattachments,checksforleakagesfrominsidetooutside,iftheballasttankshaveoverflowpriortothisinspection,removalofthedrainplugattherudderblade.Ifwaterleaksoutthisisanindicationthatthebladehassufferedwateringress(whichmayotherwisehaveremainedhidden)measurementofrudderbearingclearancesbyfeelerscanalsobeconsideredavisualapproachtoassessweardown.Dittocalibrationofanchorchainlinksbycaliperslide,conditionofrudderflangeboltsornut(s)mustbeabsolutelytightconditionofweldingatseamsandbuttsandinwayofoutletopenings.

1.1.2Closeupexamination

Ifindentationsand/ordeformationshavebeenlocated,visualcloseupexaminationsarenecessary.Theareaunderscrutinyshouldbeaccessibleforvisualinspectionwithinbodilyreach.

Suchinspectionsshouldbecarriedoutwithfloodlightetc.Agoodtorchandatesthammershouldalwaysbeavailable,aswellasascrapertoremoverustscaleanddebristorevealthebarematerialunderneath.

Incaseofdeformation

Deformationsthatmayhavebeenproducedasaresultofexternalorinternalforcesshouldbecarefullyanalyzed.

Withoutapparentextraloadsalongshell,deck,orbottom,likelihoodofthefollowingshouldbechecked:

internalmovementofcargo,liquidsetc.excessiveflexibilityofthestructure.localstressconcentrations(pointloadsexcessive).

Furtherexaminationsforfracturesandincipientcracksmaybenecessary.Alsootheridenticallocationsshouldbeexaminedtoseewhethersimilardefectsexistoraredeveloping.Incaseofcracks

locationofcrack,configurationofthestructure/element,startingpointofthecrack,lengthanddirection,depthandwidthofthecrack,possiblecause(s):

defectiveweldingofassembledparts,discontinuationofjoints,compressionortensionofadjoiningparts,twistingmotion,reducedthickness,typeofcorrosion,etc.

shouldbecheckednotonlyintherespectivearea,butalsoinotheridenticallocations,especiallyattheoppositeside.

1.1.3AreasofconcernforcracksandcorrosionLocationsofstressconcentrationandcrackraisers

Ondeck:Cornersofhatchesonweatherdecks,cornersatdeckconnectionstodeckhousesandsuperstructures,deckplatingbetweencargohatches,especiallywhereplatethicknesschanges,atbulwarkstaydeckconnections.

Underdeck:

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Cutoutsatwebframeswherelongitudinalpass,cutoutsatbulkheadswherelongitudinalpassagesareclosed,tipsofbracingplates(kneebrackets)atbulkheadconnections,areaswherelongitudinalmembersmeetverticalstructures.

Inmachineryspaces:Asaboveinunderdecklocationsandespecially

atareasofinducedvibration(aroundoscillatingmachinery),underneathofengineseats/alongfoundations,atthrustbearingseats.

LocationswhereacceleratedcorrosionislikelyGenerallywherethecoatingisinadequate,defective,orpoorlymaintained,cornersanddeadendswherewaterisrestrictedfromdrainingorflowingaway(i.e.bottom

connectionataftbulkheads),insideofscupperpipes,especiallyattheelbowswherethescuppersareledintotheshell,atbulwarkandcoamingsstaysinwayofdeckconnection,alongdeckconnectionswithcoamingsofhatches,venti1ationtrunks,airpipes,etc.,ontoporunderneathofairandventilationpipes/trunks,especiallywheregalvanizedpartsarefitted

tosteel.

Athatchcovers:betweenpaneljointsandespeciallyalongraingutters,sealingbars,andrubberchannels,alongundersideofpanelsidewallsincontacttohatchcoaming,inpocketsoflashingpoints,etc.

Athatchcoamings:alongsealingbar,

alongrollertracks.

Underdeck(cargoholds/tanks):alongafttransversebulkheadsinwayofdeck/tankdeckconnectionwherewaterorcargorestsare

likelytostay,insideofbilgetrunk,baseofsoundingpipes(wheredoublersshouldbefitted),baseofsuctionpipebellmouths,inwayofpipeclampsandfittings,attheundersidesofpipelineswherecondensateisdripping,inballasttanksalongtheareaofairbetweenfillinglevelandtanktop,atpipes,especiallyalongtheirouterrearside,fittingsandouterundersides.

1.2NondestructiveTestingMethods

Thedetectionofcracksbyvisualmethodsisratherlimited.Additionallyinternalweldingseamimperfectionsorflawsinmaterialpartscannotbediscoveredwithoutsuitablemeansofexaminationandinstrumentation.Todiscoverthesesuitablemeansofnondestructivetesting(N.D.T.)areused,suchas:

DyecheckswithliquidpenetrantsMagneticparticlechecksRadiographicchecks,orUltrasonicmeasurements.

1.2.1Liquidpenetrantmethods(dyechecks)

Onetypeoftestusesalowviscosityliquid,containingafluorescentdye.Theareatobetestedissprayedorsoakedtoallowforpenetrationbycapillaryaction,andafteratimelapseiswipeddry.Whenviewedunderultravioletlight,anyfaultswillbeshownbytheglowofthepenetrantinthem.

EstudiosdeNuticaEuropeanMaritimeSafetyAgency(EMSA)GardP&IGeneralCargoGLGroupIACSINEAVenezuelaInstituteofCharteredShipbrokersIntercargoInternationalGroupofP&IClubsIntertankoJapanCoastGuardJapanShipOwners'MutualProtection&IndemnityAssociationLloydRegisterofShippingLondonPandiMarineSocietyNDE/NDTResourceCenterParisMOUShipStrctureCommitteShipyardsDirectorySkuldSteamshipMutualP&IClubTheImarESTTheNauticalInstituteTheStandardClubTheSwedishClubUKP&IClubUSCoastGuardWestofEnglandP&I

Anothertestusesapenetrantcontainingapowerfuldye.Thisissprayedonthesuspectareawithanaerosol.Afterallowingtimeforpenetration,theareaiswipedcleanandcoveredwithaliquidwhichdriestoleavechalkysediment(developer).Thepenetrantstainsthedeveloperalongthelineofthecrack.

Thesemethodsarebasedonoldchalkandparaffintestsbutthepenetrantcanhaveahydrocarbonoralcoholbase.Someareemulsifiableforremovalbywaterspray,otherscanbecleanedoffwithsolventstoreducepossiblefirerisk.

1.2.2Magneticcrackdetection

Thistypeoftestissuitableonlyformaterialswhichcanbemagnetized(cannotbeusedforausteniticsteelsornonferrousmetals).Afterthetestthecomponentisnormallydemagnetized.

Amagneticfieldisproducedinthecomponentbymeansofanelectriccurrentorpermanentmagnetandmagneticparticlesarespreadonthesurface.Cracksarerevealedbyalineofmagneticparticles.

Thepowderusedmaybeblackironoxideheldinsuspensioninthinoil.Itispouredontothesurface,thesurplusbeingcollectedinatraybeneath.Coloredmagneticinksinaerosolsarealsoavailableandthedrymethodmakesuseofpowderonlyandthisisdustedonthesurface.Powdertendstocollectatacrackinthesamewayasironfilingswillsticktothejunctionoftwobarmagnets,placedtoendwithoppositepolestogether.

1.2.3Radiographicinspection

Xraysandgammaraysareusedforinspectionofwelds,castings,forgingsetc.Faultsinthemetalaffecttheintensityofrayspassingthroughthematerial.Filmexposedbytheraysgivesashadowphotographwhendeveloped.

Thereisarequirementforradiographicexaminationofmanywelds,particularlythoseinpressurevessels.

Defectssuchasporosity,slaginclusions,lackoffusion,poorpenetration,cracksandundercuttingareshownonthefilm.

Filmsofradiographicexaminationprovideapermanentrecordofqualityofweldsetc.andmustbeidentifiedbyserialnumbersorotherlocationmarks.Imagequalityindicatorsareplacedonoradjacenttowelds.

Radiographsareviewedbyaradiologistonauniformlyilluminateddiffusingscreen.Trainingisnecessaryfortheinterpretationoffilm,bothwithregardstothefaultsinthepartbeingexaminedandmisleadingmarksthatsometimesappearonfilm.

Askilledradiographerisrequiredfortheobtainingofphotographs.Exposuretimesforgammaraysvarywiththetypeofmaterial,itsthicknessandtheintensityoftherays.Xraymachinevoltageandexposuretimearealsovariedtosuitthematerialanditsthickness.Distancesbetweenraysource,faultsandfilmareimportantforimagedefinition.

Raysareharmfuleitherinalargedoseoraseriesofsmalloneswheretheeffectiscumulative.

Monitoringagainstoverdoseisnecessarywithfilmbadges,medicalexaminationandbloodcounts.Directexposureisavoidedbytheuseofprotectivebarriersbutthereisadangerthatobjectsintheraypathwillscatterradiation.

1.2.4UltrasonictestingInternalflawdetectionbyultrasonicmeansisinprinciplesimilartoradar.Theprobeemitshighfrequencysoundwaveswhicharereflectedbackbyanyflawsintheobject.Reflectionsarealsoreceivedbackfromtheoppositesurface.Theprobeisconnectedtoacathoderayoscilloscopewhichshowstheresultsinasimpleway.

Asingleprobecanbeused,whichcombinesbothtransmittingandreceivingfunctions.Alternativelyseparatedevicesfortransmittingandreceivingthesoundsignalsareavailable.Anyflawinthematerialbeinginspectedwillalsoproduceapeak.

Thefollowingdetailsof"USTestingofHullButtwelds"fromBUREAUVERITASWeldtestingprinciple:

Transversewavesareemittedfromanangleprobemovedontheplatesurfaceoneithersideoftheweld.

Theprobedisplacementshouldbesufficientforscanningthewholeweldoverasingleoradoubletraverse,asshownonFigure8.

Asfaraspossible,andtakingintoaccounttheplatethickness,scanfrombothsidesoftheweld,especiallyfordetectinglongitudinaldefects.

Thescanningoperationdependsonthetypeofplateedgepreparationbeforeweldingandontheconfigurationoftheweldment,i.e.onthedifficultyofaccessfortheprobe.

Theexpandedtimebasesweepshouldbechosensothatatripletraverseisdisplayedonthescreen.Thesweepmay,however,bemodifiedaccordingtothedifficultyofaccessandtotheweldedjoint.

Scanningforlongitudinaldefects(alignedinthedirectionoftheweldedjoint)isperformedbyatransversedisplacementoftheprobewithrespecttotheaxisoftheweld.Thelateraldisplacementoftheprobe,whichdependsonthedimensionsofthetransducer,shouldbesuchastoensuretheoverlappingofthescannedareasseeFigure9.

Whenananomalyhasbeendetected,theweldmaybeinspectedfurtherbymovingtheprobeparalleltotheweldandswingingitbackandforthbylato30.Thenthespeedoftimebasesweepmaybesetfordisplayinganultrasonicpathequaltoadoubletraverse.

Forscanningflushweldsonemayplacetheprobeonthecentrelinefortheweldedjointanddirecttheultrasonicbeamalongthelongitudinalaxisoftheweld.

1.3.PressureandTightnessTestsPressureortightnesstestsarerequiredduringshipconstructionandthereafteratperiodicalsurveysorafterrepairswhenthetightnessoftherespectivesection(s)hastobeprovedagain.Forsuchteststhemethodsaredifferentforeithershiptanksand/orcargotanks.

1.3.1Basicrequirementsfortanks(exceptcargotanks)Allballast,trim,feedwater,freshwater,andheelingtanksaswellasoiltanksforfuelandlubricants,shallbepressuretestedbywatercorrespondingtoawatercolumnof2.5mabovetheuppertanklevelundercertaincircumstancesapressuretestwithairfollowedbyalaterfunctiontestwiththeliquidisallowed.

Shouldthedeeploadlinebehigherthan2.5mabovetheupperlevelofthetank,thetightnessistobetestedwithawatercolumncorrespondingtothedeeploadline.Inallcasesthetestingshallbecarriedoutwithawatercolumnreachingtotheuppermostlevelofthe

overfloworairpipe.

1.3.2PressuretestofcargotankPressure/tightnesstestsofcargotanksofoilandchemicaltankers,cargotanksondrycargovessels,etc.aretobecarriedoutasfollows:Priortothevesselslaunchingatightnesstestshouldbecarriedoutbywaterpressureinthecargotanksandcofferdams.Thistestistobecarriedoutinsuchawaythatthecargotankbulkheadsandthecofferdambulkheadsaretestedatleastfromoneside.Thetestshallbecarriedoutpriortotheapplicationofthefirstprotectivecoating.

Shouldthetestwithwaternotbepossibleduringthevesselsstayatthevessel15buildingplaceordock,hydrostaticpressuretestcanalsobecarriedoutafterlaunching.

Forcargotanksthetestrequiresawatercolumncorrespondingto2.5mabovetheupperlevelofthetank.Anyspecificweightofthecargoabove1.025t/m3hastobetakenintoaccount.

Forcofferdamsawaterleveluptotheupperedgeoftheaccesshatchissufficient.

1.3.3TightnesstestofhatchcoverWeatherdeckhatchcoversshouldbetestedforweathertightness.

Thesetestsshouldusuallybecarriedoutbyhosetestingusingafirelinewithanozzleof12.5mmdiameteratapressureofatleast2.0barfromadistanceof1.5m.

1.4FunctionTestsFunctiontestsoroperationtestsshouldprovebydemonstrationthatthetestedcomponent

fulfilsitsrespectivepurposeundertheconditionsforwhichitisdesigned,andthatallrelevantaspectsofsafetyaresatisfiedwhenthecomponentisinoperation,inopenand/or

closedposition.

1.4.1BasicrequirementsFunctiontestsshallbecarriedoutwiththeSurveyoroftheAdministrationattendingandtheshipbuilderactingaccordingtothefollowingguidelines:Adefinitetestingprocedurewithdetailsofallsingletestsistobeagreedupon,containinginformationonthedutiesandactionsofallpersonsinvolved.Allrelevantsafetyvalvesand/orpressureortemperatureorflowcontrolsshouldbereadjustedandcheckedintheworkshopbeforefieldinstallationandtesting.Forreasonsofsafetythefollowingshouldbeconsideredandprovided:

meansofescape,goodlighting,includingemergencylighting,shipboardelectricityinfunctionandbackedup,includingblackoutbackup,meansforfirefightingtobeready,thepersonsengagedintestingshallbelimitedtoaminimumnumber,

thetestingdirectorshallbeselectedandnominated.

1.4.2ItemstobetestedThefollowingshouldbeconsideredforeachfunctionand/oroperationtest:

Testingofalloperationalconditionsunderwhichthesystemshouldprovesafeoperationability(suchsituationsmayalsobesimulated).

Testingofallrelevantmeansofbuiltincontrols,indicators,valves,andfittingstightnessofrespectivepiping,admissiblemotorload,etc.

Theminimumormaximumdataexpectedtherelevantlimitsshouldbereachedanddemonstrated.

1.4.3HullfunctiontestsFunctiontestsformingpartofhullsurveysareinteralia:

anchoringtestsmooringwinchtestshatchcoveroperationtestscargogearloadtestsmaneuveringtestsbollardpulltestsheelingtanktestsaccommodationladdertestspilotlifttestscargolifttestscargoramptestscargodoortests

1.5IncliningTestForeachnewbuildingoraftereachmodificationofthevesselwhichinfluencesstabilityanincliningtestistobecarriedoutpriortoseatrialsforthevesselsrecommissioningintoservice.ThistestistobecarriedoutwiththeSurveyoroftheAdministrationattendingandundersuitableconditions.

1.5.1ConditionfortestingTanksshouldbeemptyandthevesselmoreorlessinacompletedstateinrespectofinstallation

workandtheequipmentinstalled.Unavoidabletankcontentsshouldbeconcentratedtoatankwithverticalsidewalls.

Theadditionalweightsonboardshallnotexceed20%ofthelightweight,providednootherstringentreasonsrequestahigherpercentageforadditionalweights.

Tanksshouldbecompletelyfilledupto100%.Shouldatankbepartlyfilled,thefreesurfacesmustbesuchthattheydonotchangeconsiderablyduringtesting.

Vesselsmustbefreeofpersonswhicharenotactuallycarryingouttestingandcontrolmeasurements.

Thevesselshouldbeunlimitedinmovements,i.e.mooringrapefreeandnocontacttoquaywalls.Coolingwater,firefighting,sanitary,fuel,lubeoilsystemsshouldbefilleduptooperational

conditions.

Dittoboilerandcargocoolingorhydraulicsystems.Windandcurrentshouldnotaffectvessel'sfreemovementduringthetest.

1.5.2TestingprocedureTheinclinationanglesshouldbebetween1.5and2.0Inanycaselimitsof1.00and2.500haveto

bemaintained.Theinclinationstoeachsideshouldbecarriedouttwice.Thezeropointsshouldbenotedintheprotocol.

Theinclinationtestistobecalculatedbyusingthehullformdatafortheactualwaterline(buoyancywithtrimcorrection).

Incliningtestscanbeomittedforsistervesselsofthesametypebuiltbythesameshipyardwithoutdeviationofbuildingdatawhichcouldinfluencestability,providedthetestresultsoftwopreviouslybuiltvesselsproducecomparableresults.Forthisthewrittenapprovaloftheowners(andpossiblyoftheAdministration)isrequired,butadeadweightcalculationistobecarriedoutinthepresenceoftheSurveyorfortheAdministration.

Ifappliedfor,theinclinationtestcanbeomittedwithhugetankersandbulkcarriersofalengthofabove250mprovidedagaintheshipowner(andpossiblytheAdministration)approvesthisinwritingandthedeadweightcalculationiscarriedoutundertheattendanceoftheSurveyoroftheAdministration.

Forvesselswithbuiltinheelingmoments,f.i.withcranesatonesideonly,alsothismomentistobecalculatedinconnectionwiththeevaluationoftheincliningtest.

1.6Thicknessmeasurements

1.6.1AnchorcablesAnchorchainsareusuallymeasuredbyusingcaliperslides.

Chainlinksinthevicinityofthechainendsshouldbemeasuredin2crosssectionaldirections.

Thelocationsformeasurementmustbechosenatthelinkendswheremaximumwearand/ordeformationistobeexpectedand/orvisible.

1.6.2ThicknessmeasurementsofhullscantlingsIngeneral,thicknessmeasurementsaremadebyultrasonicthicknessgauges(seeabove1.2.4).

Ifcarriedoutprofessionallyandinarepresentativeway,measurementsoftheactualthicknessofscantlingscangenerallyrevealtheactualoverallconditionofavesselwithrespecttoitsstructuralstrength.

Thescopeofthemeasurementsrequiredisdeterminedbytherulesoftheclassificationsocietybasedonthetypeandageofavesselundersurvey.Theactualconditionsofthestructure,verifiedbyvisualobservations,mayrequestprematureand/oradditionalmeasurements.

Asageneralrule,thesmallerthethicknessesthemoretheextensivemeasurementshavetobe.

Inareasofheavycorrosiontestingistobeincreasedtoshowtheextentofwearandtoallowproperjudgmentiftheareaistoberenewedorotherwiserepaired.

1.7VibrationMeasurementsDetailedvibrationinvestigationsshouldbemadeduringthedesignperiodofavesseltopredictthevibrationlevelsinaccommodationandworkingspacesandtoavoiddamagebyexcessiveaccelerationstohullstructuresandmachinery.

Forvesselswithslowspeed2strokeenginesanoverallvibrationexaminationshouldbecarriedoutforhullandsuperstructure.

Vibrationscanbeexcitedbyperiodicalforces,suchasthemainengine(asafunctionofthefiringfrequency),theperiodicalpropellerbladeforcesatbladefrequency,andotherfreevibratingmasses.

Tanksidesandshellplatingareasinwayoftheengineroomandpropellerareashouldbedesignedsothat

structuralfrequenciesarehigherthantherespectiveexcitingfrequency.

Forvesselswithmediumspeedenginesthepossibilityofpropellerbladeinducedvibrationsshouldbeexamined.Thistypeofengineinducesexcitationswithfiringfrequenciesbetween23and33Hz.Calculations,ofnaturalfrequenciesoflocalstructuresarethereforenecessary.

Whetherothersystemsasmasts,rudderarrangementsorshaftlinesaretobeinvestigated,dependsontheindividualcase.

Localstructuresshouldhave'naturalfrequenciesofabout2025%abovethehighestmainexciterfrequency.Suchcalculationsmaybecarriedoutbyusingsimpleformulas,orbythefiniteelement(FE)methods.

FEmodelswhichareusedforstrengthcalculationsmayalsobeutilizedforthevibrationanalysis.

Classificationsocietiescangreatlyassistshipownersorbuilderswithsuchcalculationswhichmayavoidexpensivemodificationsorstructuralalterationsafterunfavorableseatrials.

Vibrationmeasurementsareusuallycarriedoutinnewbuildingsduringseatrials.Occasionallythesemeasurementsarenotsufficientandhavetoberepeatedinafullyorpartlyloadedconditionofthevesselandoccasionallyalsoundercertainengineoperationmodes.

Measurementsarethencarriedoutbyaspecialsurveyorteam,usingvibrationregistrationequipmentpositionedinspeciallyselectedlocationstorecordsimultaneouslyengineoperationmodestogetherwithlocalstructuralexcitationfrequencies,amplitudesandaccelerationinordertoidentifyresonances.

2.INSPECTIONSCHEMES

TherecognizedClassificationSocietieshavedevelopedsystematichullinspectionprogramswhichensurethatavessel'sstructuralparts,componentsandcompartmentsaredulykeptundercontrolbyperiodicalexaminationsandaresubjectedpartiallyortotallytotheabovedescribedvisualinspections,testingandexaminationmethods.

Thesesurveyprogrammesare:PeriodicalClassRenewalproceduresafter4years,withapossibleextensionto5yearsif

satisfactorilysubjectedtoaclassextensionsurveyContinuousSurveyproceduresforHull(CSH)withtherenewalsurveyprogramdividedintopartial

inspectionsofabt.20%foreachyear)overaperiodof5yearsClassExtensionSurveysDrydockingSurveysatintervalsofatleast2.5years.

Allthesescheduledinspectionsystemsensurethatavesselsconditionisregularlycontrolledandproperlysupervisedwithintherespectivesurveysystem.

Therespectiveinspectionschemesareasfollows:

2.1PeriodicalClassRenewalSurveys(alsocalledSpecialSurveys)FortheRenewaloftheClass,theshipshull,machineryincludingelectricalinstallationsandtheautomatic/remotecontrolsystemsaretobesubjectedtosurveysatthefixedintervals.

Aclassrenewalsurveycan,underspecialcircumstances,becarriedoutinseveralsteps.Here,thetotalsurveyperiodmustnotexceed12months.

Abottomsurveywithinthisperiodoftimecanlikewiseberecognizediftherequirementsforclassrenewalarefulfilled.

TheexaminationofcertaincoveredpartsmaybedispensedwithataClassRenewalSurveyiftheSurveyoriscompletelysatisfiedoftheirefficientcondition,andiftheOwnerundertakestohavethemexposedforexaminationwithin12months.AcorrespondingentrywillbemadeintheCertificateofClassification.

ClassRenewalsHullistobeeffectedinthesequenceI,II,III,IVandsubsequenttoIV.TheClassRenewal,No.IVandthefollowingcorrespondtoClassRenewalIII.

2.2ContinuousSurveyHullCSH

InsteadoftheClassRenewalprocedureaccordingto2.1theOwnermayapplyforContinuousClassRenewalforHullandMachinery.TheClassRenewalprocedurecan,however,alsobeadoptedonlyforthehulloronlyforthemachinery,includingtheelectricalplant.

TherequiredsurveysunderCSHextendoveraperiodnotexceeding5years.IthastobemadesurethatduringtheContinuousSurveysallpartsoftheshipshulland/ormachinery,includingtheelectricalplant,besurveyedatintervalsnotexceedingtheperiodsnormallyrequiredforthemaintenanceofclass.

TheSurveyormayreinspectcompartmentsorstructuresaredeemednecessary.

Attheendoftheperiodofclasstheextentofsurveyofthehulldependsonthescopeoftherespectiveclassrenewaldue,IorIIorIIIorIV.

Whereboth,aship'shullandmachinery,includingtheelectricalplant,aresurveyedinaccordancewiththe

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continuousclassrenewalprocedure,the5years'periodofclassisvalidforbothsectors.Thisisconditionalupontheprescribedsurveyintervalsandrespectivescopeofsurveyrequiredbeingobserved.

Whereeitheronlythehullorthemachinery,includingtheelectricalplant,issubjecttothecontinuousclassrenewalprocedure,a4years'periodofclassisvalidforbothsectors.Classextensionby12monthsispossible.Surveysaccordingtothecontinuousclassrenewalprocedureareperformedalsoduringtheperiodofclassextension.

2.3ClassExtensionSurveysOnOwners'requestelasscanbeextendedbynotmorethan12monthsaftersurveyofthevesselatleasttothescopeoftherequirementsforanAnnualSurveyafloat.Classmaybeextendedonlyifhullandmachinery,includingtheelectricalplant,areinperfectconditionandif,sincethebottomwaslastsurveyed,noincidentsoccurredresultingindamagesexpectedtohavebeencausedtotheunderwaterbody.

Shipshavingacharacterofclassificationdifferentfrom100A4(highestGLclasscharacter)cannothavetheirclassextended.

Drydockingintervalsaretobeobservedforclassextensions.

AtaClassExtensionSurveytheshipistobeinspected,ifpracticable,whenitisnotloaded,sothatthehatches,thecargoholds,thetweendeckspaces,thewatertightdoors,etc.canbeexaminedifnecessary,tankswillalsobeexamined.Inthecaseofoiltankersandshipscarryingcombinedcargoes(e.g.OBOships)theballasttankslocatedinthecargoareawillbesubjectedtoageneralconditionsurvey.Aninspectionofthemachinery,includingtheelectricalplant,istobemadetoverify,inparticular,satisfactoryoperation.Automatic/remotecontrolsystemsaretobeexamined,takingintoaccountrecordsofoperation.

2.4DockingSurveysUnderwaterhullinspectionsatregularintervalsshallensurethattheoutsideandthesteeringfacilityofashipremaininasatisfactorycondition.Suchinspectionsarealsocarriedoutforthecontrolpfthepropeller,theshaftlinebearingsandseals.Inadditioninletandoutletpiping,valves,seachestsandseafiltersareexamined.

Aspecialtypeofunderwaterhullsurveyistheinwatersurveywhichcanbeappliedunderspecialconsiderations.

Forseagoingshipswithcharacterofclass100A4aninwatersurveymayberecognizedasasubstituteforeverysecondperiodicalbottomsurvey,provided

therequiredspecialequipmentisavailable,documentshavebeenissuedandtrialrequirementscompliedwithandifthesurveyiscarriedoutasrequiredandwithapprovedfirmsandsatisfactoryresults,

thissurveyisnotpartofaclassrenewal.

Forshipsofmorethan10yearsofagetheintervalsbetweendrydockingmustnotexceed2.5years.

ResolutionA.997(25)EResolucinA.997(25)SResolutionA.1020(26)EResolucinA.1020(26)S

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