Lorem Ipsum DolorVestibulum magna nisl, dictum non, dignissim nec, tristique sed, tellus

Bluewater Turret BuoyTechnical Description

“ The Bluewater turret buoy eliminates the disadvantages of the turntable buoy. The buoy body with deckhouse rotates around a central turret fixed to the seabed. The deckhouse protects the main bearing and all mechanical and electrical equipment and offers a safe place to work during operations and maintance. From experience with this buoy design, Bluewater is confident in offering an extended guarantee on the main bearing for the design life time of the turret buoy system.”

1

Contents

1 Introduction 2

1.1 BluewaterCompany 2

1.2 GeneralapplicationofSPMsystems 2

1.3 Summaryoftheadvantagesofthe

TurretBuoy 3

2 Developmentoverviewofthe

differentSPMbuoytypes 4

2.1 HistoryoftheSPMloadingbuoys 4

2.2 Thirtyyearsofexperiencewithboth

TurntableandTurretBuoys 7

2.3 Overviewofhighlightsofthe

BluewaterTurretBuoy 8

3 Technicaldescriptionofthe

TurretBuoy 13

3.1 General 13

3.2 Buoybody 13

3.3 Skirtandprotection 13

3.4 Flat,unobstructeddeck 13

3.5 Turretandspider 14

3.6 TheMainBearing 14

3.7 TheProductSwivel 15

3.8 Protectiondeckhouse 16

3.9 BoatLanding 17

3.10 FloatingHoseInstallationPlatform&

ProtectionFrames 17

3.11 MooringLug 17

3.12 ChainHawse-pipesandturret

lockingsystem 18

3.13 ChainStoppers 18

3.14 AncillaryEquipment 19

4 AuxiliaryEquipment 21

4.1 General 21

4.2 BuoyMooringArrangement 21

4.3 TankerMooringArrangement 22

4.4 FloatingHoses 22

4.5 TheSubmarineHoseString(s) 23

5 EnvironmentalProtection 24

5.1 General 24

5.2 Stabilitybuoy 24

5.3 Enclosedsystem 24

5.4 Doublesealsproductswivel 24

5.5 Flexiblejoints 24

5.6 Leakdetection&recuperationsystem 25

5.7 RemotePLEMvalveoperatingsystem 25

5.8 Remoteoperation&monitoring 25

5.9 Surgereliefsystem 25

5.10 Break-awaycouplings 26

5.11 Doublecarcasshoses 26

6 RequirementstostartanSPMproject 27

6.1 Introduction 27

6.2 Informationrequired 27

6.3 Contractingstrategy 28

2

1 Introduction

1.1 BluewaterCompany

AtBluewater,wedesignandsupplyinnovativeCALMbuoysandotherMooringandTransferSystems.

Bluewaterhassuppliedmorethanseventy(70)oftheseSPMandCBM/MBMsystemsworldwide,suchas:

• SinglePointMooring(SPM)SystemsincludingCatenaryAnchorLegMooring(CALM)Buoys,TurretBuoysand

Turntablebuoys

•ConventionalBuoyMoorings(CBM)

•Disconnectable,ExternalandInternalTurretMooringSystemscompletewiththeirfluidSwivelAssemblies

•TowerMooringSystems

1.2 GeneralapplicationofSPMsystems

SPMsystemsaretypicallyusedforloadingoroffloadingtankers,offshorenearthecoast.TheSPMsystemis

normallyapointofexportorimportforarefinery,tankfarm,powerplantorotheronshoreinstallations,forthe

transferofcrudeoranyliquidorgasproduct

SPMsystemscanalsobeusedfortheexportofcrudeoilatanoffshoreoilproductionlocation.

3

1.3 SummaryoftheAdvantagesoftheTurretBuoy

Bluewater has designed and supplied various Turntable and Turret type SPM buoy systems worldwide.

BothCALMbuoytypesarelargesuccessesinthemarketandbothhaveimpressivetrackrecords.

TheTurretBuoyisthethirdgenerationofSPMbuoydesign.ThedifferencebetweentheTurretBuoyandearlier

generationSPMbuoys,theconventionalTurntablebuoyandtheBogeyWheelbuoy,isinthegeometryofthebuoy.

Whereaswiththeearliergenerationsthevulnerablepartsareoutsideandexposedtoseawater,theTurretBuoy

offersthepossibilitytokeepallcriticalequipmentprotectedinsidethedeckhouse.

BasedonBluewater’sexperiencewithbothCALMbuoytypes,andbasedontheexperienceofourClients,the

mostprominentadvantagesoftheTurretBuoyconceptare:

• Safetyduetoflat,notobstructeddeck,norotatingormovingpartsontheoutside,easyaccesstothebuoyfrom

aworkboatandthepresenceofaprotecteddeckhouse,

• Operationalreliabilityduetotheeffectiveprotectionandventilationofthemainbearing,overboardpipingand

allequipment.

AnSPMbuoyisnormallyacriticalequipmentsinceanotherlargecapital investmentlikearefinery,tankers

farm,productionfacilitiesorelectricalplantdependsonthebuoy.Therefore,theavailabilityoftheSPMbuoy

isimportantfortheoverallinvestment.TurretBuoyshaveaproventrackrecordof20-25yearsofuninterrupted

servicetothemainasset(refinery,etc),withouttheneedforperiodicremovalorchange-outandtheassociated

downtimeoftheentirefacility.

• Lowermaintenancecostsduetoeasierandaccessiblemaintenanceandthepossibilityofkeepingthebuoyin

thewaterforlongperiodswithoutoverhaul(mainbearingandallequipmentiswellprotectedinsidethedeck-

house).Onlypreventivemaintenanceisneeded;noreplacementofheavypartsoffshore,incontrastwith,for

example,thewheel-and-railbuoydesign.

Duetoeffectiveprotectionofthemainbearingandotherequipmentinsidetheweatherproofdeckhouseand

othertechnicaldesignbenefits,sofarnoneoftheTurretBuoysworldwidehasseentheneedforperiodicover-

haulduringitslifetime.

• TurretBuoyshavethelargestresistanceagainsttankercollisions.Thefactsshowthat,despitethatmanyTurret

Buoyshavesufferedseverecollisionswithworkboatsortankers;noTurretBuoyhasbeentakenoutofservice

duetothesecollisions.However,inthecaseofturntablebuoys,manyhavebeentakenoutofserviceaftercol-

lisions.

ThebenefitsoftheTurretBuoyresultinthelowestTotalCostofOwnershipforthisSPMbuoycomparedtoothers.

ThetrackrecordoftheTurretBuoyhasproventhattheTurretBuoy,whichisdesignedtostayinthewaterduringits

lifetime,isfarmoreeconomicaltotheend-userthananyotherSPMbuoytype(non-Turrettype)whichneedsperiodic

removal.

4

2 DevelopmentoverviewofthedifferentSPMbuoytypes

2.1 HistoryoftheSPMloadingbuoys

CBMorMBMsystems

Thedevelopmentofloadingbuoysstartedinabout1920,whenthegrowthintankersizesdemandedtheexten-

sionofharbourfacilitiesintodeeperwater.UptotheinstallationofthefirstgenerationofSinglePointMooring

(SPM)systems,tankersweremooredwithinapatternoffourtoeightmooringpoints,consistingofrigidbuoys

mooredtotheseabedbyachainandanchor.ThisConventionalBuoyMooring(CBM)orMulti-BuoyMooring

(MBM)systemdoesnotenabletankerstoweathervaneandhasthereforeoperationallimitations.

SPMsystems

The1stgeneration(wheelandrail),2nd(turntable)and3rd(turret)generationbuoysystemsarecollectively

called“SinglePointMooring”(SPM)systems.Duetothecharacteristiccatenarycurveoftheanchorchainsfixing

theSPMbuoysystemstotheseabed,themooringsystemswiththesebuoysystemsarealsocalled“Catenary

AnchorLegMooring”(CALM)systems.

FirstgenerationCALMbuoy:WheelandRailbuoy

ThefirstbuoyswecanindicateastheforerunnerofthecurrentbuoytypeswerebuiltandinstalledinSwedenin

1959fortheSwedishNavy.Thesefirstgenerationbuoyswere

oftheWheelandRail(orBogeyWheel)type.Ithasabuoy

bodywithacentralmoonpoolandarotatingbogeyplatform

on wheels, allowing the tanker to weathervane around the

buoy.Thefluidtransferrunsthroughaswivel.Thisbuoyhas

onlyonebearing,theswivelbearing.Thebogeywheeltable

issupportedbywheelsrunningonrails.

WheelandRailbuoy

5

Thewheelandrailbuoyhasseveraldisadvantages,thereforesecondgenerationCALMbuoywasquicklydevel-

opedwithactiveinvolvementofoilmajorShell.Inco-operationwithanengineeringcompanyintheNetherlands

abuoysystemwasdevelopedwhichischaracterisedbyacylindricalbuoybody,mooredtotheseabedbyfourto

eightanchorchainsandarotatingplatformstructureontop,theturntable.Thetankermooringhawserandthe

flexiblefloatingloadinghosesareconnectedtotherotatingplatform,enablingthetankertoweathervanearound

thebuoy.Thisbuoytype,schematicallydepictedinthefigurebelow,iscalledthe“TurntableBuoy”.

SecondgenerationCALMbuoy:Turntablebuoy

TheTurntablebuoy,thesecondgenerationCALMbuoy,hasbeenaworldwidesuccessandmanyofthesebuoys

wheresolduntil1980.However,theexperiencehasshownthattheturntablebuoyneedsperiodicoff-location

overhaul(dry-docking),whichinitselfisofaclient’sdisadvantage.

• ThereisaDirectcostinvolvedfromoffshoredismantling,transport,dry-docking,yardrepairsandre-installation

offshore.

• Indirectcost:non-availabilityoftheTurretBuoyduringtheoverhaulperiod,typicallyaperiodoftwomonthsor

longer,duringwhichtheterminalcannotservicetheconnectedasset(e.g.refineryorproductionfacility)and

whichmaythereforebeforcedtostopitsoperations,causingdowntime.

• Often thisdowntime issolvedbypurchasingasparebuoy.Thismeansadoublepurchaseexpenditure, in-

creasedmaintenance,storageandconservationcostsasanadditionalbuoyneedstobestoredandmaintained.

• Riskisinvolvedinthemarineremovalandreconnectoperations,transportandrepairworksanduncertaintyis

introducedforthereturndateandhenceavailabilitytotheassetitservices,e.g.refineryorplant.

Furthermore,inbetweentheperiodicoverhauls,themaintenanceinthewaterrequiresaconsiderableeffort.The

deckisobstructedbytheturntableandwalkingonthe

buoymeansclimbingupanddowntovariouslevels.

Duetotherotatingturntablethereisnosafetyhand

railingaroundtheperimeterofthebuoy,noprotecting

deckhousetocoverthevulnerableequipmentsuchas

themainbearinganditisdifficulttomooramainte-

nanceoroperationalworkboattothebuoy.

Turntablebuoy

6

ThirdgenerationCALMbuoy:TurretBuoy

Bluewaterdevelopedanew,improvedbuoyconceptinordertoovercomethedisadvantagesoftheTurntable

andCALMbuoys.Inthisdesign,thebuoybodyitselfcanfreelyrotatearoundaturretstructure.Theturretis

mooredtotheseabedbytheanchorchains.Thebuoyoffersanenormousimprovementintermsofsafety,ease

ofmaintenance,protectionanddurability.TheexperienceworldwidehasshownthattheTurretBuoycanremain

inoperationatitsoriginallocationforaperiodofatleast25years,withoutperiodicoff-locationoverhauland

withoutreplacementofheavyparts(suchaswheelsorrailsofthebogeywheelbuoy).Thenewtypeofbuoyis

calledthe‘TurretBuoy’.

Since1980theTurretBuoyhasbeenverysuccessfulinthemarketandisthepreferredchoiceofmanymarine

terminaloperators.After thedevelopmentof theTurretBuoy, theconceptof turretmooringhasbecomethe

leadingtechnologyforthepermanentmooringoftankersasFloatingProduction,StorageandOffloading(FPSO)

andFSOunits.

TheschematicsbelowillustratethedifferenceincrosssectionoftheTurntableandTurretBuoy:

TurntableBuoy TurretBuoy

7

TurretBuoy

2.2 ThirtyyearsofexperiencewithbothTurntableandTurretBuoys

Overthepast30years,BluewaterhasdesignedandsuppliedmanyTurntable(2ndgeneration)andTurret(3rd

generation)SPMbuoysystems.

SinceBluewateristheonlyfabricatorofbothTurretandTurntabletypesofbuys,wehavebeenabletocompare

theoperationalperformanceofbothbuoytypes.

However,afteralmost30yearsfabricatingbothsystemsandreceivingoperationalfeedbackfromourclientsand

fromotherusersofbuoys,ithasshownabigdifferenceintheclientsatisfactionofeachtypeofbuoy.

8

2.3 TechnicalhighlightsoftheBluewaterTurretBuoy

TheBluewaterTurretBuoyconcepteliminatesthedrawbacksofearliergenerationbuoydesignsandprofitsfrom

severaldistinctadvantagesinherenttotherotatingbuoybody.

ThemostprominentadvantagesoftheTurretBuoyarehighlightedbelow:

1. Safety:TheTurretBuoyhasaflatdeck,notobstructedbyaturntableoranyothermovingpartsandiseasily

accessibleviaaproperboatlandingdesignedtomooraworkboatalongsidethebuoy.

2. Safety:TheTurretBuoyhasalargeboatlandingtowhichaworkboatcanbesafelymoored,givingoperating

personnelsafeaccesstothebuoy.Downtimeduetoinaccessibilityisthereforelessthanwithothertypes

ofbuoys.

3. Durability:TheTurretBuoyisprovidedwithadeckhouse.Themostimportantcomponentforthemechani-

calfunctioningofthebuoy,themainbearing,ispositionedinsidethedeckhouseandisthereforeoptimally

protectedagainstallforcesfromtheenvironment.

Personnelonthedeckofaturntablebuoyneartotherotat-

ingarmoftheturntablewhichcanmove.Thepersonnelis

notprotectedbyahandrailing.

PersonnelondeckofaTurretBuoy.

Safety:nomovingparts;safetyhandrailaroundthe

perimeterofthebuoy.Alsovisibleisthelargeboatlanding

9

4. Durabilityandmaintenancefriendly:Extrafeatures,suchasadditionalelectronic(control)equipment,winch,

instrumentsandvalvesarealsofittedinsidetheprotectedareaofthedeckhouse.

5. Durability:Thehawserload,aswellasloadsgeneratedbytanker-buoycontact(tankerkissing)orbywork

boat,isdirectlytransferredintothebuoybody.Duetothelargemassofthebuoybody(incl.deckhouseand

allequipment)andtheaddedmassofthewateraroundthebuoybody,loadsandvibrationsfromthehawser

areabsorbed,resultinginonlyalimitedtransferoftheseloadstothemainbearing.Asaresult,theopera-

tionallifetimeofthemainbearingisbetterensured.

TurretBuoy:externalloadsonthebuoybodyareabsorbedbymassand

wateraddedmass,resultinginonlyalimitedtransferoftheseloadsto

themainbearing.

Turntablebuoy:externalloadsontheturntable

willpass100%throughthemainbearing

10

6. Durability:Theloadsgeneratedbytanker-buoycontact(tankerkissing)andbymooringaworkboatagainst

theboatlanding,areabsorbedbythemassofthebuoybodyandsurroundingwaterasdescribedabove,

thusprotectingthemainbearingfromexcessiveshockloads.

7. Maintenancefriendly:Theflatand“clean”deckstructurecombinedwiththeenclosureofallequipmentin

thedeckhousereducessignificantlythemaintenanceandrepaircoststhroughoutthelifetimeofthebuoy

system.

8. Safetyandmaintenancefriendly:Operating, inspectionandmaintenancecrewscanboardthebuoyand

workundersafecircumstances,protectedfromsunorrainandallowsworkeveninrelativelyroughseasas

mostoftheworkisdoneinsidethedeckhouse.Downtimeduetorestrictioninmaintenanceandrepairis

thereforelowerthanwithothertypesofbuoys.

9. Durability:Bylockingthedoorsofthedeckhouse,unauthorisedaccesstotheequipmentcanbeprevented.

10. Durability:Theoverboardpipingisatthelowerpart,closetothewaterline,directlysupportedbythebuoy

structure.Anadequatefendersystemprotectsthepipingfromtankercollisions.

Overboardpipingdirectlyconnectedto

buoyhull–strongsupport

11. Durability:WithanyCALMbuoy,atslackweather,thefloatinghosestringmaywraparoundthebuoy

body.TheadvantageoftheTurretBuoydesign–wheretherotatingbuoybodycanbeseenasareel-is

thatthehosesautomaticallyunwrapwhentheweatherpicksup,orwhenthehoseispulledoutbya

smallservicecraft.

Overboardpipingwellprotectedbyfenderbelowandabove

theflanges.

11

12. Durability:Asthechainstoppersarenotfittedattheouterperimeterofthebuoybody,butinthespider

underneathandwellwithinthecontoursofthebuoybody,theyarenotpronetodamagebytankercontact.

TurntableBuoy TurretBuoy

13. Durability:Thankstotheinwardpositionofthechainstoppers,theclearancebetweenthetankerbowand

theanchorchaincatenaryislarger,thuseliminatingtheriskofatankerhittingthechainstoppersandreduc-

ingtheriskoftankersdamagingtheanchorchain.

14. Durability:ThecentreofgravityoftheTurretBuoyisrelativelylow,providingahigherstabilityduringinstal-

lation,operationandmaintenanceofthebuoy.Italsoreduceswearontheupperchainlinks.

15. Flexibility:TheshapeoftheTurretBuoyisnotrestrictedtoacylindricalshapeonly.Thesquareshapeis

structurallyidealtofithingesforawishboneMooringarm,permanentlyorsemi-permanentlymooringofa

tanker:

12

16. Flexibility:Extrafeatureslikeasurgereliefsystem,encompassingreliefvalves,tanksandpumps,canbe

fittedinthedeckhouseandinthebuoybody.

17. Safety:HAZOPstudiesontheTurntableandTurretBuoyconcepthaverevealedthattheTurretBuoyissafer

forpersonnelandenvironment.InparticulartheprobabilityforspillageincaseofTurretBuoyisconsiderably

lessthanincaseofTurntablebuoy.

Asaresultoftheadvantagesdescribedabove,boththeoperationandmaintenancecostsofaTurretBuoyare

substantiallowerthanwithaTurntableBuoy.Mostimportantfortheuseristhemorereliable,higheravailability

oftheTurretBuoysystem,reducingcostondemurrageandondelaysinthetransferofcargo.

TomostoftheforegoingaspectscanbeseeninthepicturesofrecentBluewaterTurretBuoyprojectswhichare

enclosedinthisreport.

Thesurgereliefvalvesareprotected inside

thedeckhousetogetherwiththeswiveland

as shown in thispicture, togetherwith the

flexiblejointsandthemainbearing.

FullintegrationofaSurgeReliefSystemispossibleintheTurretBuoy,

withallpartsprotectedinsidethedeckhouseandbuoybody.

13

3 TechnicaldescriptionoftheTurretBuoy

3.1 General

TheTurretBuoyconsistsoftwostructuralmaincomponents,theturretstructure(thepartthatisfixedtothesea-

bed)andthebuoybody(rotatingpart).Theturretstructureislocatedinthecentreofbuoybody.Theturretand

buoybodyareconnectedatdecklevelbymeansofarollerbearing.Theconnectionbetweenthepipingsections

intheturretandinthebuoybodyismadebymeansofafluidswivelalsooutfittedwitharollerbearing.Thetanker

ismooredtothebuoybodyviaahawserandcanfreelyweathervaneinresponsetochangingweatherconditions,

therebyrotatingthebuoybodyaroundtheturret.

ThemaincomponentsoftheTurretBuoysystemwillbehighlightedinthefollowingsubsections.

3.2 Buoybody

ThebuoybodyforaTurretBuoycanbearectangularorcircularconstruction.Thebuoybodyisdividedinwater-

tightcompartments,eachofthemaccessibleviaamanholeinthedeck.Thecompartmentsaredesignedtomeet

theexistingClassrequirementsrelatedtothedamagedstabilitysituation.Themanholesgivingaccesstothebuoy

compartmentsareflushwiththedecksurface.

3.3 Skirtandprotection

Alongtheperipheryofthebuoybody,justabovebottomlevel,askirtisfittedtoprotectthebuoybodyagainst

directcontactwithships.Thefreeside(s)ofthebuoybodyareprotectedagainstcontactswithverysmallcrafts

andfloatingobjectsbymeansoffenders(half–pipes),weldeddiagonallytothehullplating.

3.4 Flat,unobstructeddeck

Thedeckofthebuoybodyisflat,unobstructedandwithahandrailingallalongitsperiphery.

14

3.5 Turretandspider

Theturretassemblyconsistsofaturretshaftandachaintableorspider.Theturretshaftisalargediameterconi-

calsection.Atthetopsidethemainbearingisfitted,atthebottomsidetheturretisclosedbyadiaphragmplate.

Theinsideoftheturretisthereforeadrycompartment,whichisdirectlyaccessiblefromthedeckhouse.Inside

theturret,valvesbetweensubmarinehosesandswivelaswellasgeostatic(control)equipmentcanbemounted.

Thespiderorchaintableisaboxgirderframing,whichsupportsthechainstoppersthroughwhichtheanchor

chainsareattachedtomoorthebuoyatlocation.

3.6 TheMainBearing

Thebuoybodyandtheturretshaftareinterconnectedbymeansofalargediameterbearinglocatedatdeck

level.ThismainbearingisthelargestofthetwobearingsinaTurretBuoy;theotherbearingispartoftheprod-

uctswivel.Themainbearingisathree-racerollerbearingandismountedonreinforced,machinedfoundation

flanges,fixedbyhightensionmountingbolts.Thebearingisthemostcriticalmechanicalcomponentofthebuoy.

Maximumattentionisthereforegiventothecorrectmachiningofthebearingsupportsandthefittingofthe

bearing.Thebearingispositionedinthedryenvironmentofthedeckhouseandinternalsealsprovideadditional

protectionofthebearingagainstingressofwateranddust.

15

Lubricationofthemainbearingcanbedonethroughthegreasingpointsprovidedinthebearingrings.Grease

samplingpointstomonitortheconditionofthebearingarelocatedatthebearinguppersurface.Ifrequired,the

lubricationcanalsotakeplacefromoneortwomanifoldswithgreasepipestothegreasingpoints.Asanextra

feature,afullyautomatedgreasingsystemcanbeordered.

3.7 TheProductSwivel

While themainbearingprovides themechanical connection in theTurretBuoy, the swivel provides thefluid

transferbetweenthefixedandtherotatingpartsoftheTurretBuoy.Theswivelallowsunlimitedrotationofthe

buoywithoutmixingthedifferentproductchannels.Itisequippedwithitsownbearingandseveralproductseals.

Beingoneofthemostcriticalcomponentsofthebuoysystem,Bluewaterdesignsandbuildstheswivelsitself.

Bluewaterhasextensiveexperienceinthedesignandfabricationofdifferenttypesofproductswivels,suchas

singleandmulti-productswivels,andhigh-pressureswivelsforspecialapplications.

16

Easyaccessenablesregularinspectionsontheproductswiveltodetectleakageoroilseepageattheflangecon-

nections.Theswivelbearingisgenerallymanuallygreasedatperiodicintervalsviathegreasepoints/nippleson

thefixedflangebetweenthebearingbolts.Theswivelhasadualsealconstruction.Anyleakageofthefirst,inner

sealcanbemonitoredbyleakdetectioninthespacebetweentheinnerandouterseal.Intheunlikelyeventthat

leakagethroughtheinnerandoutersealoccurs,thespillagewillbecontainedintheturretcompartment,pre-

ventingpollutionoftheenvironment.Asanextrafeature,anautomaticleakdetectionsystemcanbeprovided.

3.8 Protectiondeckhouse

OneofthemainadvantagesoftheTurretBuoy:awatertightdeckhouseisfittedoverthecentralareaoftheTurret

Buoy.Itprotectstheturret,mainbearing,productswivel,electricalequipment,winchandallotherequipment

againstallenvironmentalforcessuchassun,rain,windandseawater.Atthesametime,itallowsventilationof

themainbearingtoavoidaccumulationofcondensedwater.Shieldedlouverpanelslocatedclosetothedeck-

houserooflevelensurepermanentventilationoftheinterior.

Thedeckhouseisdesignedtowithstandallloadsduetowindandovercomingwaves.Thedeckhousehastwo

doorsinoppositewalls.Oneofthedoorsneartotheboatlandingisextrawideandhasaliftingbeamextending

fromtheinsidetotheoutsideofthedeckhousetoenablethetransferofequipmenttoandfromthecentralarea

insidethedeckhouse.Intheceilingofthedeckhousearailbeamisfittedoverwhichalittletrolleyhoist(which

ispartofthestandarddelivery)canberuntoperformsmallliftingoperationsinthedeckhouse.Thisgreatly

facilitatesrepairormaintenanceworkstotheequipmentinthedeckhouse.

Ontheroofofthedeckhouseadeckhasbeencreated,whichisprovidedwithhandrailing.Thedeckisgenerally

largeenoughtofitthebatteryboxes,solarpanels,navigationlightsandantennas.Thedeckisaccessibleviaa

fixedorremovableladderwithsafetycage.

17

3.9 BoatLanding

AnotherstrongpointoftheTurretBuoy:alongtheentiresideofthebuoybody,agenerouslysizedboatlanding

isfittedtoprovidesafeaccesstothedeckofthebuoy.Theboatlandingisconstructedfromtubularsteelmem-

bersandcompriseshorizontalfenderpipesintegratedatdeckandskirtlevelandverticalmemberswithrubber

fenderstopreventship-to-steelcontacts.Theboatlandingisoutfittedwithaladderinarecess,forsafeaccess

fromsmallerboats,withbollardsforberthingsmallcraftsandwithaliftingdevicetofacilitatethetransportof

equipmentontothebuoy.

3.10 FloatingHoseInstallationPlatform&ProtectionFrames

Atthelocationoftheoverboardpiping,aworkplatformisprovidedtofacilitatethedisconnectionandre-connec-

tionofthefloatinghose(s).Theplatformisconstructedfromtubularsteelsectionsandgalvanisedsteelgrating.

Atmaindecklevelasolidprotectionframeoftubularsteelisprovidedtogivefurtherprotectiontotheoverboard

piping.

3.11 MooringLug

Onthedeckofthebuoybodyamooringlughasbeenfittedforconnectingthemooringhawser.Frompractical

experience, thefloatinghosestring(s)andthehawserattachmentpointonthebuoybodyshouldapparently

bekeptapart,buttheanglebetweenthemshouldbelessthan90degrees.OnthesquareTurretBuoytype

thisisachievedbyplacingthemooringlugatacornerofthebuoybodyonthesidewheretheoverboardpiping

isfitted.

Overthemooringluglocation,aprotectionframefromtubularmembersisfittedtoprovideprotectionincaseof

failureofthehawserundertension.

18

Themooringlugcanbefittedwithanelectronichawserload-measuringdevice.Themonitoringequipmentfor

thisdeviceispositionedinthedeckhouse.Dependingontherequirements,warningsforoverloadingthehawser

canbesignalledthroughthenavigationlamps,thefoghornor,viaatelemetrysystemtoamobileorfixedshore

station.

3.12 ChainHawse-pipesandturretlockingsystem

Dependingonthenumberandconfigurationofthemooringlegs,twoorthreehawse-pipesarefittedinthebuoy

bodyanddeckhousewalltofacilitatefastinstallationofthemooringlegs.Severalanchorlegscanbepulledin

ateachposition,

Theturretcanbeeasilylockedintotherequiredpositionsbymeansofastraightforwardlockingpininthedeck-

house.Thislockingpincanalsobeusedtofixtheturrettothebuoybodyforgeneraltransport,installationand

maintenancepurposes.

3.13 ChainStoppers

Thechainstoppersareabletofreelyoscillateverticallyandtoalignwiththechainangle,preventingwearon

thefirstchainlinksbelowthechainstopper.Thelockingofthechainsinthechainstoppersisachievedbytwo

automaticlatches,whichallowthechaintobepulledinuntiltherequiredpositionorchainangleandthenlock

thechainsinthestopperautomatically.

19

3.14AncillaryEquipment

Winch

Awinchisinstalledonthebuoydeck,insidethedeckhouse.Thisallowsthewinchtobeeasymaintainedand

alwaysavailabletofunction.Thewinchisprotectedinsidethedeckhouseandthereisnoneed,aswithprevious

generationbuoytypes,toremovethewinchfromthebuoy.Thecompressedairorhydraulicsnecessarytorunthe

winchhastobeprovidedfromaworkboat.Thewinchcanbeusedforthere-tensioningoftheanchorchains,to

pullinandconnectthesubmarineandfloatinghosestringsandtoperformliftoperationsforanybuoycompo-

nent,suchasswivel,valves,flexiblejoint(s)etc.Forenablingthesedifferentliftoperationsandtoguidethewinch

wiretotheworklocation,sheavesarepresentatvariouslocationsinandontopofthebuoydeckhouse.

20

Navigation Aids

Anobstructionlight,foghorn,andradarreflectorareprovidedandmountedonthebuoyasanavigationaidfor

shippingandtoreduceanyhazardtohappen.Theelectronicequipmentrunsonthepowerpacksinstalledina

largebatterybox.Thepositionofthebatteryboxisoutsidethedeckhouseinorderthepreventvapourbuild-up

inthedeckhouse.Thebatteriesarere-chargedbysolarpanelswhicharepositionedonthedeckhouseroof.

Safety Equipment

Thestandardsafetyequipmentdeliveredonboardofthebuoyencompassestwoportablefireextinguishers,

eachstoredinawatertightredcabinet,andtwolife-buoysfittedwithselfilluminatinglightsandbuoyantlifelines.

21

4 AuxiliaryEquipment

4.1 General

ThemaincomponentofacompleteSPMterminalsystemistheSPMbuoyitself.Inaddition,anumberofauxiliary

equipmentcomponentsareanintegralpartofsuchaSPMsystem.Thesecomponentsaredescribedinthefol-

lowingsubsections.

4.2 BuoyMooringArrangement

TheTurretBuoyissecurelyanchoredtotheseabedbymeansofasetofmooringlines(legs)whicharefixedto

theseabedwithanchorpoints.Generally,anaveragebuoysystemisfixedtotheseabedwithsixmooringlegs.

Sometimesthisnumberisincreasedtoeightorninelegs.Dependingontheprojectsituation,thesixmooring

legsareequallyspacedorclusteredinthreeseriesoftwoorthreelegs,120degreesspaced.(typicalmooring

patterns…;TurretBuoycanaccommodateany)

Themooringlinesareinmostcasesheavychainswithlinkdiametersizesrangingfromthreetosixinches.The

lengthofthelegsvarieswiththewaterdepth,thetankersizeandtheloadconditions.Lengthsof200to600

metersarecommon.

Eachmooringlegwillbeconnectedtoananchorpoint.ThesecanbeHighHoldingPower(HHP)marineanchors,

drivenordrilledpiles(opentubularsections),suctionpilesandgravityboxesorframes(boxesfilledwithgravity

material),respectivelyframeswithgravitymaterialontop.Thefinalselectionoftheanchorpointconceptwill

dependonthesoilconditionsandtheavailabilityofrequiredinstallationequipment.

22

4.3 TankerMooringArrangement

Inprincipletwotankermooringsituationscanbeidentified:thetemporarymooringofatankerforthedurationof

aloadingoperation(generally24hours)andthe(semi-)permanentmooringofatankerfordurationinexcessof

weekslikeinaFloatingStorageandOffloading(FSO)system.Forthe(semi-)permanentsituation,severalbuoy-

to-tankermooringconstructionsexist,likewishbone,yokeandrigidarmconnectionstructures.Whereasthese

structuresareveryprojectspecific,thefocusofthisdocumentisonthetypicalloadingoroffloadingsituations,

wherebythetankerismooredforabout24hours

Thetankermooringarrangementisahawserarrangement,encompassingapolyestermooringlinewithchain

sectionsonbothsidestopreventwearandtearattheconnectionpoints.Thepolyestersectionofthemooring

linehascertainelasticitycapacities,whichdampenstheloadsandtankermovementsintheoverallmooring

system.Forthedesign,fabricationanduseofthesehawsersystemsextensivecodesandstandardsexist.(OCIMF

publication“StandardsforEquipmentEmployedintheMooringofShipsatSinglePointMoorings”).

4.4 FloatingHoses

Theconnectionofthetankerwiththebuoypipingismadebytheuseofoneormorefloatinghosestrings.The

numberandsizeofthestringsdependsonthemaximumsizeofthetankerstobemooredandloadedviathe

buoysystemandtherelatedpumpingcapacity.Alsoforthedesign,constructionanduseoffloatinghosesexten-

sivecodesandstandardsexist.(OCIMFpublication“BuoyMooringForumHoseStandards”)

Thefloatinghosesfromthebuoytothetankerwillbeelectricallycontinuousuptothelastthreehosesatthe

tankerend.Thehoseshaveaminimumreservebuoyancyof20%.

AidsfortheInstallationandMaintenance

Adequateequipmentisprovidedonthebuoytosimplifytheinstallationandmaintenanceofthefloatinghose

string(s).

23

4.5 TheSubmarineHoseString(s)

Thesubmarinehosesystemwillbedesigned,manufacturedandtestedaccordingtotherequirementsofthelatest

OCIMFpublication“BuoyMooringForumHoseStandards”.

Thesubmarinehosestring(s)connectsthePLEMtothebuoy’spipingandwillbedesignedwithsufficientlength

toadapttotheexcursionsandheavemotionsofthebuoy.

AidsfortheInstallationandMaintenance

Ahosepull-inhawserpiperunsfromthemainbuoydeckleveldownthroughtheturret.Theliftlinefromthe

winchisrunthroughthispipe,pullingthesubmarinehosestring(s)untilitismeetsitsconnectionpointwiththe

buoypiping.

24

5 EnvironmentalProtection

5.1 General

TheTurretBuoysystemhasbeendesignedtooperatetothehigheststandardsofsafetyandtominimizethe

riskforpersonnelinjuriesand/ordamagetotheenvironment.Allaspectswithanimpactonsafetyinoperating

thebuoysystemhavebeenanalyzedandmeasurementsaretakenwherepossibletoenhancethesafety.This

alsocomprehendsthetrainingofoperationpersonnelandtheprovisionofadequateoperationdocumentsin

achievingthesafetygoals.Thesubsectionsbelowhighlightthemainaspectswheresafetyhasbeenofparticular

importance.

5.2 Stabilitybuoy

Comparedtootherbuoydesigns,theTurretBuoyhasarelativelowcentreofgravityandasubsequenthigh

stability.Thisenhancesthemotionbehaviourofthebuoy,makingitasaferplacetoworkon.

Thebuoybodyisdividedintosixoreightwatertightcompartments.Thedesignofthesecompartmentsissuch

that,incasethebuoyisinvolvedinanaccidentandtwoadjoiningcompartmentsarepenetratedandflooded,the

buoyhassufficientresidualbuoyancyandstabilitylefttoremainafloatanddonotcapsize.

5.3 Enclosedsystem

TheTurretBuoyisdesignedasanenclosedsystem,i.e.allmechanicalcomponentsintheproductlinesinthe

buoysystemaresituatedinaconfinedspace.Thisspaceisthedeckhouseandtheturretspace.Asdescribed

before,theturretisclosedatthebottomsideandisthereforeadryspace.Also,thefloorinthedeckhouseis

watertightandwiththehighthresholdsofthedoors,nofluidscanstreaminoroutofthedeckhouse.

Incaseoftheunlikelyeventthataleakageoccursinanyofthemechanicalcomponentsintheproductline(prod-

uctswivel,valves,andflexiblejoints),thespillagefromthisleakingwillbecontainedinthedeckhouseand/or

theturretspace.Thechancesthatsuchaleakageoccurswithoutbeingnoticedisunlikely,asthebuoyisalways

mannedduringloadingoperationsandbecausecertainpipingcomponentsliketheproductswivelhaveanactive

leakdetectionsystem.

5.4 Doublesealsproductswivel

Theproductswivelisoneofthemostcriticalcomponentsinabuoysystem.Tohavefullcontroloverthequality

ofthiscomponent,Bluewaterdesignsandbuildstheproductswivelsforitsownbuoyandturretsystemprojects.

Theseswivelsareprovidedwitharollerbearing,adualmainsealingconstructionanda leakagemonitoring

system.Incasetheprimary,innersealstartsleaking,theleakagecanbenotedbythemonitoringsystem,butno

spillagecanoccurasthesecondarysealwillcontainthefluidwithintheswivel.

5.5 Flexiblejoints

Inthepipingsystem,betweenthefluidswivelandthefixedpipeworkonboardthebuoy,highqualityflexible

25

jointsarefitted.Theseflexiblejointspreventanysecondaryforcestobeintroducedtotheswivelandtothepip-

ingsystemwhichmayresultfromsmallmisalignmentsbetweenthebuoyandtheturretpartofthebuoysystem

duringrotation.Thesesecondaryforcesmayintroduceunexpectedfatiguetothepipingsystem,whichonitsturn

mayresultintocracksandleakage.

5.6 Leakdetection&recuperationsystem

AllBluewaterswivelsarestandardprovidedwithamechanicalleakdetectionsystem.Asanoptionalextra,the

systemcanbeextendedwithanelectronicmonitoringsystem,whichcaneitherbeconnectedtotheonboardnavi-

gationlightandfoghorn,orcanbeconnectedviaatelemetrysystemtoa(mobile)monitoringstationonboard

thetankeroronashorebase.Inadditionthesystemcanbeextendedbyarecuperationsystem,whichcollects

theleakedfluidandre-injectsitautomaticallyintothemainpipingsystem.

5.7 RemotePLEMvalveoperatingsystem

ThePLEMhasbeenoutfittedwithvalveswiththepurposeofisolatingthepipeline(s)andortheriser(s)fromthe

restofthefacility.Thisincaseareplacementorrepairofanyofthecomponentsisrequired.Ifthevalvesareused

forthispurposeonly,theoperationofthePLEMvalvesbymeansofdiverassistanceisthemostcommon,widely

acceptedprocedure.

Itwillenhancethesafetyofthebuoysystemsubstantiallyif,duringtheperiodsbetweenloadingoperations,the

valvesareclosedandthefluidpathisdividedintoseveralcompartments.Thiscanbecombinedwithprovisions

forflushingthelineinwholeorpartlytoreplacetheproductwithwater.Inparticularthisisworthwhiletobe

consideredfortherisers,buoypipingandfloatinghoses.

InordertomaketheregularopeningandclosingofPLEMvalvespracticallyfeasible,thesevalveshavetobe

operatedremotely,i.e.fromthebuoyorviaatelemetrysystemfromtheshorebase.Toachievethis,anelectri-

cal/hydraulicumbilicalcanbeinstalledbetweenthePLEMandthebuoy(totheturretpart).Intheturretspacea

nitrogen/hydraulicpowerpackandoperatingconsoleisinstalled.Duetothegeo-staticpositionoftheturret,no

electrical/mechanicalswivelsarerequiredintheumbilicalline.

5.8 Remoteoperation&monitoring

Ifdesired,thevalveoperationscanbecommandedand/ormonitoredattheshorebaseviaatelemetrysystem.

5.9 Surgereliefsystem

Surgeisthephenomenonofhigh-pressureshockwavesinapipingsystemduetosuddendrasticchangesinthe

flow.Thiscanforinstancebecausedbythesuddenclosureofavalveortheactivationofabreak-awaycoupling.

Thesesuddenhighpressuresmaycausedamagetothebuoypipingsystemsand/ortothehosearrangements,

whichmaybefollowedbyaspillage.

Fromexperienceitisknownthatthesurgephenomenonoccursinpractice.Topreventthepossiblesubsequent

damage,asurgereliefsystemcanbeinstalledasafullyintegratedsafetysystem.Forthis,surgereliefvalves

26

areinstalledintheuppersectionofthemainpipingsystem.Thesevalvesopenautomaticallywhenacertain

predeterminedpressurelevelisexceededandasmallvolumeoftheproductflowsdirectlyintotanksfittedinto

oneofthebuoybodycompartments.

Aftersuchasurgeoccurrence,thetankcanbeemptiedbyre-injectingthefluidsbackintothemainpipingby

meansofanelectricalorair-drivenpump.

5.10 Break-awaycouplings

Duringtheloadingoperations,thetankerismooredtothebuoysystembymeansofahawserandtheloading

takesplaceviathefloatinghosesbetweenthetankerandthebuoy.Incasethehawserfailsandthetankerdrifts

away,thereisalargeriskthatthefloatinghosescannotbedisconnectedandclosedproperlybeforethelines

arestretched.

Topreventthebreakingofthehose(s)andacertainspillageoftheproductintothesea,automatic,mechanical

break-awaycouplingscanbeinstalledineachofthefloatinghosestrings.Thesecouplingswillfunctionwhena

pre-settensionforceinthecouplingisexceeded.Thecouplingwillsplitandtheopenendsofthecouplingwill

closeoffveryfast,limitingthespillagetoanabsoluteminimum.

5.11 Doublecarcasshoses

Duringtheoperationofthebuoysystem,thefloatinghosesaresubjecttowearandtear.Thiswearandtear

canbeontheinsidefromerosionofparticlesintheproductfluidsandontheoutsidefromUVlight,seawater

andfrommechanicaldamage.Thedoublecarcasshoseshaveadoubleskin,whichlaylooseovereachother.

Whetherthedamageiscomingfromtheinsideortheoutside,onceoneoftheskinsispenetratedandleaking,

thehosescanstillbeusedforcompletionoftheongoingloadingoperation.Thispreventsdemurragecostsof

thetankerincasehosereplacementcannotbepostponed.

27

6 RequirementstostartanSPMproject

6.1 Introduction

Theneedforamarineterminalisalwayssubsequenttodecisionsonmuchlargerprojectsliketheerectionofa

refinery,powerplantorstoragefacility.Oncetheneedforamarineterminalhasbeendefinedandthetypeof

terminalisdetermined,consultantsarecontractedtopreparearecommendation.Itisofteninthisphasethat

Bluewateriscontactedbyeitheraconsultantorbytheclientdirectlyforinformationandadviceregardingthe

applicationofanSPMsystem.Bluewaterhasalwaystakenanactiveapproachininformingclientsonthepossibili-

tiesofSPMsystems,whichmostlyconcernsSPMbuoysystems.Mostimportantinthisprocessistoexplainthe

functioningofanSPMbuoysystemandtoprovideinformationonwhatistechnicallypossibleandwhatshould

beincludedinthefunctionalspecificationforsuchanSPMbuoysystem.

6.2 Informationrequired

Inordertobeofassistanceintheselectionprocessandtocometoasatisfactory,costefficient(pre-)designfor

anewSPMbuoysystem,twokindsofinformationarerequired:

- Environmentalinformation

- Functionalinformation

TheClienthastomakeavailableencompassonthefollowingenvironmentalinformation:

- Geographicalinformation(whereistheproject)

- Meteorologicalinformation(weatherconditions)

- Nauticalinformation(waveconditions,current,temperature)

- Bathometricinformation(seabedcondition)

- Soilsurveyreport.

IfcertaininformationisnotavailablewiththeClient,Bluewatercanassistinobtainingthisinformationfromexpert

companies.

28

ThefunctionalinformationprovidedbytheClientshouldinclude:

- Siteinformation: - Detailedsitemap

- Lay-outoftheprojectfacilities

- Productdata: - Productstobeimportedorexported

- Compositionofproduct(s)

- Temperature

- Viscosity

- Gravity

- Tankerdata: - Size(orrangeofsizes)

- Frequencyloadingoperations

- Max.operatingconditions: - Significantwaveheight

- Waveperiodrange

- Current

- Wind

- Tidalrange

- Waterdepth

- Pipingrequirements: - Flowrate

- Piggingrequirements

- Designpressure

- Subseapipelinediameter(s)

DependentontheexperienceofClientwithsimilarterminaloperations,Bluewateradvisestomutuallydevelop

thefunctionalrequirementspriortothestartofanybudgetorpricingexercise.Bluewaterhasavastexperience

withdesigningandbuildingSPMsystemsallovertheworld.Thisexperiencemightpreventthedefinitionof

insufficientorexuberantrequirements,whatmayresultinanunsatisfactoryperformanceoftheSPMfacilityor

intoohighprojectcosts.

6.3Contractingstrategy

The marine part of an SPM buoy terminal includes two main components: the SPM buoy system and the

pipeline(s)connectingthissystemwiththefacilitiesonshore.Forthedesign,constructionandinstallationof

theSPMandthepipeline,twoexpertcontractorsareinvolved,beingtheSPMdesigner/supplier,likeBluewater

andthepipelinedesigner,supplierandinstallationcontractor.Thissecondpartyisgenerallyalsoinvolvedinthe

installationoftheSPMsystem.

TheClienthastheoptionstoeithersubcontracteachportionofthemarineterminaldirectlytoaspecialized

29

companyortosubcontractthecompletemarinepartoftheterminaltooneEPCIcontractor.Inthefirstcase,Client

hastomanagethetwocontracts,theinterfacebetweenthetwocontractsandtheinterfacewiththeconnection

totheonshoreplant.Inthesecondcase,Clienthastomanageonlyonecontractandoneinterface(atthecon-

nectiontotheshoreplant).

BluewaterofferstoexecutethecompletemarinepartoftheterminalasanEPICcontractor.Dependentonthe

situationandtheextentofeachofthescopeparts,Bluewaterofferstoexecutetheprojectasamaincontractor

orasaconsortiumwithapipelinecontractor.

PhotoReportofaBluewaterTurretBuoy

InthissectionaphotoreportisenclosedshowingavarietyofbuoyprojectsBluewaterhasexecutedintherecent

years.ThephotosprovideafurtherimpressionoftheTurretBuoydesignandtheadvantagesofthisdesignas

highlightedinthisbooklet.

Ocensa,Colombia,TLU-2,TurretBuoywithworkboatmooredtoboatlanding

30

ApacheStagField,Australia,TurretBuoyduringinstallation

Apache,StagField,Australia,FSOmooredtoTurretBuoy

31

Ocenca,Colombia,TLU-2Terminal,InteriordeckhousewithBluewaterswivel

Figure1LargeandEasyAccessBoatlanding

32

Ocensa,Colombia,TLU-2Terminal;PipingforSurgeReliefSysteminsidedeckhouse

Woodside,LegendreFieldAustralia;

Overboardpipingsolidconnectedtobuoyandwellprotected

The Netherlands

Bluewater Energy Services B.V.

Marsstraat 33

2132 HR Hoofddorp

The Netherlands

Tel +31 (0)23 568 2800

Fax +31 (0)23 565 2053

United Kingdom

Bluewater Services (U.K.) Ltd.

Bluewater House, Badentoy Crescent Portlethen

Aberdeen AB12 4YD

United Kingdom

Tel +44 (0)1224 403 300

Fax +44 (0)1224 403 340

Angola

Bluewater International B.V. “Sucursal”

Trav. Do Teatro de Providencia

No. 9, 3 Andar-Apto 1, Coqueiros

Ingombotas, Zona 4

Luanda, Angola

Tel/Fax +244 (0)222 330 573

www.bluewater.com January 2011