Tanker Conversions to FPSO

International Association of Oil & Gas Producers

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OGP Marine Risks Workshop Proceedings

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Tanker Conversions to FPSOsRob Potthurst, Lloyd’s Register

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Presentation onPresentation on

Tanker ConversionsTanker Conversionstoto FPSOsFPSOs

RobRob PotthurstPotthurstOffshore Floating UnitsOffshore Floating Units

Oil and GasOil and Gas

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OverviewOverview�� Market summaryMarket summary�� LR ExperienceLR Experience�� Key issuesKey issues�� Rules and RegulationsRules and Regulations�� Hull strength and fatigueHull strength and fatigue�� Some lessons learnt (hopefully)Some lessons learnt (hopefully)


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FPSO / FSOMarket

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Total 70+ units worldwideTotal 70+ units worldwide

NewbuildNewbuild(30%)(30%)

ConversionConversion(70%)(70%)

ShipShip--type Floating type Floating Production UnitsProduction Units

Tanker Conversions to FPSOs - Rob Potthurst, Lloyd’s Register ()


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s Future Floating Offshore Future Floating Offshore Installation ProjectsInstallation Projects

Analysis of asset types identified under the Analysis of asset types identified under the most likely development solutionmost likely development solution

TLPTLP(11%)(11%)

FSOFSO(8%)(8%) SemiSemi

(3%)(3%)

SPARSPAR(18%)(18%)

FPSOFPSO(60%)(60%)

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F(P)SO CapabilitiesF(P)SO CapabilitiesTypical RequirementsTypical Requirements� Storage 200,000 - 2,000,000 barrels� Production 30,000 - 300,000 bopd� Vessel 100,000 - 350,000 tonnes� Water depth 70 - 1500 metres� Topsides 2000 - 33000 tonnes� Risers 1 - > 30� Wave height benign - > 30 metres� Air temp -20oC - > 30oC



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LR Experience

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s LR ExperienceLR Experience

� FPSO and FSO Units� Steel Fixed Platforms ~ 800� Buoys� Pipelines� Jack-ups� Semi-submersibles� Concrete Structures

~ 40

~ 15~ 70~ 50~ 75~ 30



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s Floating Production Installations - LR Worldwide Experience

BraziBrazill33

CanadaCanada33

NorthNorthSeaSea1919

MediterraneaMediterraneann44

VietnaVietnamm22

AustraliaAustralia55

PhilippinePhilippiness22

NewNewZealandZealand

11

West of West of ShetlandsShetlands

11

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s Recent Conversion ExperienceRecent Conversion Experience�� Amerada Hess TritonAmerada Hess Triton

�� Amerada Hess FifeAmerada Hess Fife

�� Amerada HessAmerada Hess BluewaterBluewater DurwardDurward/Dauntless/Dauntless

�� BluewaterBluewater BleoBleo HolmHolm

�� ExproExpro EfiatEfiat AbanaAbana

�� MAS CurlewMAS Curlew

�� PetechimPetechim VietsovpetroVietsovpetro DragonDragon

�� PetrobrasPetrobras RoncadorRoncador

�� PetrobrasPetrobras Barracuda (ex Barracuda (ex PP.MoraesPP.Moraes))

�� Reading & Bates Reading & Bates SeallionSeallion

�� Shell Todd Maui BShell Todd Maui B

�� SLP/SLP/MaerskMaersk ConocoConoco MacCullochMacCulloch

�� ShellShell soreenasoreena



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s Example of ConversionExample of Conversion

ConocoConoco MacCullochMacCullochNorth Sea Producer North Sea Producer -- TeessideTeesside

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s Example of ConversionExample of Conversion

FPSO �Whakaaropai�for Shell Todd Maui B Field

FPSO �FPSO �WhakaaropaiWhakaaropai��for Shell Todd Maui B Fieldfor Shell Todd Maui B Field

Oil Storage Capacity approx. 760,000bbls



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ConversionsKey Issues

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Overall requirementsOverall requirements

�� Shallow/DeepwaterShallow/Deepwater�� Turret/Spread mooring Turret/Spread mooring

arrangementsarrangements�� Permanent / Permanent / DisconnectableDisconnectable

mooringsmoorings�� Small/Large displacement hullsSmall/Large displacement hulls�� Benign/Harsh environmentsBenign/Harsh environments�� Project management requiredProject management required



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What makes an FPSO different What makes an FPSO different from a trading tanker?from a trading tanker?�� Operations and safety requirementsOperations and safety requirements�� Layout and arrangementLayout and arrangement�� Specified service/locationSpecified service/location�� Rules and regulationsRules and regulations�� Design/construction/commissioningDesign/construction/commissioning�� InIn--situ inspection/maintenancesitu inspection/maintenance

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s Key Choice DriversKey Choice Drivers�� Project and client requirementsProject and client requirements

�� time to first oiltime to first oil�� location/environmentlocation/environment�� functionfunction�� life cycle costslife cycle costs

�� Statutory and National Authority requirementsStatutory and National Authority requirements�� Ship Yard scheduleShip Yard schedule

�� availability / capability / priceavailability / capability / price�� locationlocation

�� Availability of suitable tonnageAvailability of suitable tonnage�� capacitycapacity�� condition, agecondition, age�� upgrading scopeupgrading scope

�� New build: 2 to 3 years; Conversion: 1 to 2 yearsNew build: 2 to 3 years; Conversion: 1 to 2 years



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s Hull Selection Issues (conversion)Hull Selection Issues (conversion)�� Vessel age, condition and service historyVessel age, condition and service history

�� hull global strengthhull global strength�� remaining corrosion marginsremaining corrosion margins�� remaining fatigue liferemaining fatigue life�� structural steelwork replacementstructural steelwork replacement

�� Mooring structureMooring structure�� internal or external modificationsinternal or external modifications�� structural reinforcementstructural reinforcement

�� Topside integrationTopside integration�� structural reinforcementstructural reinforcement

�� UpgradesUpgrades�� equipment / systemsequipment / systems�� coatings / corrosion controlcoatings / corrosion control�� machinerymachinery�� accommodationaccommodation

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s ConversionConversion -- Major WorksMajor WorksExisting HullExisting Hull�� Removals/modificationsRemovals/modifications

�� hull steelwork, coatings etc.hull steelwork, coatings etc.�� propulsion and other machinerypropulsion and other machinery�� rudder/steering gearrudder/steering gear�� accommodation, deckhouses andaccommodation, deckhouses and helideckhelideck�� piping systemspiping systems

�� UpgradesUpgrades�� marine and topsides control system integration marine and topsides control system integration �� fire protection systems and their integrationfire protection systems and their integration�� power generation systems and their integrationpower generation systems and their integration�� cargo tank venting arrangement cargo tank venting arrangement �� ballast and cargo oil pumps and valvesballast and cargo oil pumps and valves�� inert gas systeminert gas system�� utility systems (utility systems (egeg water, steam, heating)water, steam, heating)



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s ConversionConversion -- Major WorksMajor WorksHull AdditionsHull Additions

�� turret or spread mooring system, equipment, etcturret or spread mooring system, equipment, etc�� riser porches or fluid transfer system and piping riser porches or fluid transfer system and piping �� provision of thrustersprovision of thrusters�� installation of process deck supportsinstallation of process deck supports�� process systems process systems PAUsPAUs, flare and piping, flare and piping�� blast wallsblast walls�� life saving equipmentlife saving equipment�� fire and gas equipment and systemsfire and gas equipment and systems�� evacuation measuresevacuation measures�� bulwark and breakwaterbulwark and breakwater�� lifting equipmentlifting equipment�� loading instrument (computer)loading instrument (computer)�� offloading systemoffloading system

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s Mooring ArrangementsMooring Arrangements

BowBowMooringMooring

InternalInternalTurretTurret

MooringMooring

SpreadSpreadMooringMooring



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s Turret Mooring SystemsTurret Mooring Systems

Large Internal TurretLarge Internal Turret Small Internal TurretSmall Internal Turret Riser Turret MooringRiser Turret Mooring(D)(D)

External Turret MooringExternal Turret MooringSubmerged TurretSubmerged TurretProduction (D)Production (D)

Buoyant TurretBuoyant TurretMooring (D)Mooring (D)

InternalInternal ExternalExternal

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s General arrangementGeneral arrangement

�� Living quarters at the sternLiving quarters at the stern

Living quartersLiving quartersOilOilSep.Sep.

P.G.P.G.

GasGasComp.Comp.

MeteringMetering

Flare TowerFlare Tower

TurretTurret

Living quartersLiving quarters

P.G.P.G.

OilOilSep.Sep.

GasGasComp.Comp.

MeteringMetering

Flare TowerFlare Tower

TurretTurret

�� Living quarters at the bowLiving quarters at the bow



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FPSORules and Regulations

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s Governing RegulationsGoverning Regulations

�� Local National AuthorityLocal National Authority

�� Class Rules for FPSO InstallationsClass Rules for FPSO Installations

�� Flag StateFlag StateInternational ConventionsInternational ConventionsSOLAS, MARPOL, LOADLINE, SOLAS, MARPOL, LOADLINE, TONNAGETONNAGE



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s National RegulationsNational Regulations

�� U.K.U.K. �� HSE safety case and verificationHSE safety case and verification

�� Canada(NS)Canada(NS) �� CNOPB, TC(flag) ,RQF, classCNOPB, TC(flag) ,RQF, class

�� BrazilBrazil �� (BNW), class, flag(BNW), class, flag�� NigeriaNigeria �� Marine Notice, class, flag(N)Marine Notice, class, flag(N)�� Gulf of Mexico Gulf of Mexico �� Follows�Follows�

__________________________________________________________International ConventionsInternational ConventionsSOLAS, MARPOL, LOADLINE, SOLAS, MARPOL, LOADLINE, TONNAGE�TONNAGE�

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s DefinitionsDefinitions

�� ClassClass�� Rules Based / Risk BasedRules Based / Risk Based

�� CertificationCertification�� To Regulations and CodesTo Regulations and Codes

�� VerificationVerification�� To Performance CriteriaTo Performance Criteria

�� ClassClass\\CertificationCertification\\VerificationVerificationoften combinedoften combined



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s Rules for a Floating Offshore Rules for a Floating Offshore Installation at Fixed LocationInstallation at Fixed Location

Rules andRegulations

Part 4


Part 4


Part 4


Part 4


Part 5


��

Part 4Rules andRegulations

��



Part 1ARules andRegulations

Part 1

Parts 2 to 9

Technical Regulations

Parts 2 to 9Parts 2 to 9

Technical RegulationsTechnical Regulations

Part 1APart 1A

Risk Based ApproachRisk Based Approach

Part 1Part 1

RegulationsRegulations

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s Scope of LR FPSO RulesScope of LR FPSO Rules

�� LR Rules cover the following LR Rules cover the following aspects :aspects :

�� Hull and Marine SystemsHull and Marine Systems

�� Mooring SystemsMooring Systems

�� Risers (optional)Risers (optional)

�� Process plant (optional)Process plant (optional)

�� Drilling plant (optional)Drilling plant (optional)



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s LR ClassificationLR Classification

�� AlternativesAlternatives�� Prescriptive Rules Prescriptive Rules -- business as usualbusiness as usual

�� Flexibility of Risk Based optionsFlexibility of Risk Based options

�� Risk Based SolutionsRisk Based Solutions�� Applicable to Design of both hull and Applicable to Design of both hull and

topsides, although generally hull topsides, although generally hull adopts prescriptive approachadopts prescriptive approach

�� Applicable to Periodic Inspection Applicable to Periodic Inspection (draft LR guidance available)(draft LR guidance available)

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AA6cAA6c

LR Guidance NotesLR Guidance NotesSupporting the RulesSupporting the Rules

� An Overview of Regulatory Issues� Conversion of Tankers for Floating

Production Service

� Ship Type Hull Structural Appraisal andsupplement Additional Structural Aspects

� Positional Mooring Systems and supplement FibreRopes for Offshore Moorings

� Periodic Inspection� Design Appraisal of Semi-Submersible Units



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ConversionsHull strength and fatigue

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s Hull Design ConsiderationsHull Design Considerations

� hull strength, arrangement and materials� 100-year site specific criteria� local connection details and fatigue life (min 20 years)� range of loading conditions� vessel motions and accelerations� mooring system and hull integration � process support structure� slamming and green seas� sloshing� helideck, cranes and cargo offloading system� accommodation� corrosion control � construction tolerances and fabrication quality� philosophy for in-service periodic survey� interfaces



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s Model Testing Model Testing -- supportsupport

�� To support design calculationsTo support design calculations�� Riser & mooring designRiser & mooring design�� Loading, excursions, separation Loading, excursions, separation �� FPSO/shuttle tanker interactionFPSO/shuttle tanker interaction�� Hull motions, slamming, green Hull motions, slamming, green

seasseas

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s Ship Rules Ship Rules -- basic hull strengthbasic hull strength

�� Parametric equations for :Parametric equations for :�� Wave bending moment/shear forceWave bending moment/shear force�� inertiainertia�� Hull modulusHull modulus

�� FEA requirement FEA requirement (strength/fatigue)(strength/fatigue)

�� Local strengthLocal strength�� WW service (limitation options)WW service (limitation options)�� Equivalence through IACSEquivalence through IACS



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s FPSO Hull FPSO Hull -- Global StrengthGlobal Strength�� Minimum class rule standardMinimum class rule standard�� Site specific environmental criteriaSite specific environmental criteria�� Effect of mooring system Effect of mooring system

(+(+weathervaningweathervaning))

�� Process facilitiesProcess facilities�� Long term service (at site)Long term service (at site)�� Range of loading conditions Range of loading conditions

(including inspection and accidental cases)(including inspection and accidental cases)

�� Slamming/green seasSlamming/green seas

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FF2FF2--1g1g

Global Hull Design Global Hull Design �� wave BM & SFwave BM & SF

� Still water loading conditions often more severe for FPSOs

� Class Rules permit review of Rule versus Site specific wave bending moments and shear forces

� Will depend upon site environmental criteria� Harsh environment wave BM and SF are close to and

may exceed Ship Rule requirements� Benign environment are less than Ship Rules but not to

be taken less than 70% of unrestricted service Ship Rulerequirements in general

� Multisite operation may require assessment� Owners requirements, eg corrosion margins� Towing and temporary conditions to be

considered



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s 100 Year Hs / 100 Year Hs / TpTp ContoursContours

2 6 10 14 18 22 26 304

6

8

10

12

14

16

18

2020

4

Hs1 2 i�

Hs2 2 i�

Hs3 2 i�

302 TP1 2 i� TP2 2 i�� TP3 2 i��

West of ShetlandWest of Shetland

Northern North SeaNorthern North Sea

Central North SeaCentral North Sea

Hs

Tp

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s Some typical criteriaSome typical criteria

HsHs TpTpNigeriaNigeria 3.13.1 7.67.6Offshore IranOffshore Iran 5.95.9 10.210.2AustraliaAustralia 7.27.2 11.111.1U.K. CentralU.K. Central 13.013.0 15.215.2West of ShetlandWest of Shetland 17.117.1 16.016.0Nova ScotiaNova Scotia 16.016.0 14/1814/18



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s Accidental LoadsAccidental Loads

�� Collision due to supply boat / Collision due to supply boat / shuttle tanker / icebergshuttle tanker / iceberg

�� Dropped objectDropped object�� Explosion / blastExplosion / blast�� Ultimate strength criteriaUltimate strength criteria

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s Steel GradesSteel Grades

�� Class rules for shipsClass rules for ships�� New requirements for low New requirements for low

temperature operationtemperature operation�� Structural categoriesStructural categories�� ThicknessThickness�� LocationLocation



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s Hull Strength/Fatigue FEAHull Strength/Fatigue FEA�� Cargo / ballast tank areaCargo / ballast tank area�� Hopper knuckle connectionHopper knuckle connection�� Mooring structure and hull integrationMooring structure and hull integration�� Riser porches and supporting structureRiser porches and supporting structure�� Topsides support structure and hull integrationTopsides support structure and hull integration�� Flare tower support structureFlare tower support structure�� Access tower support structureAccess tower support structure�� Offloading station support structureOffloading station support structure�� Main crane pedestals and support structureMain crane pedestals and support structure�� HelideckHelideck structurestructure�� Additional locations depending on vessel Additional locations depending on vessel

function and owners requirementsfunction and owners requirements

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s Fatigue LifeFatigue LifeFactors of SafetyFactors of Safety

Substantial consequences of failure are defined as loss of life, uncontrolled outflow of hazardous products, collision orsinking and should include for progressive failure scenarios.

Note 1 Note 1 : includes external components which can be dry inspected / repa: includes external components which can be dry inspected / repaired.ired.Note 2 Note 2 : includes external components below the minimum operating draft: includes external components below the minimum operating draftwhich can only be inspected in water , but dry repairs could be which can only be inspected in water , but dry repairs could be carried out.carried out.

Inspectable/Repairable

Fatigue Life FactorConsequence of Failure

Non-substantial SubstantialYes, dry

(see note 1)1 2

Yes, wet(see note 2)

2 4

No 3 10



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s Typical Critical AreasTypical Critical Areas

Process SupportsProcess Supports

Stress ConcentrationStress Concentration

MisalignmentMisalignment

WeldingWelding

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s FPSO Fatigue Enhancement FPSO Fatigue Enhancement Details (conversion)Details (conversion)Examples of modification to hull longitudinal connection detailsExamples of modification to hull longitudinal connection details

Additional lugAdditional lug

Longitudinal/Transverse frameLongitudinal/Transverse frameconnectionconnection

AdditionalAdditionalbracketbracket

LongitudinalLongitudinal

Transverse frameTransverse frame

Shell plateShell plate

AdditionAdditionalalbracketbracket







AdditionalAdditionalbracketbracket

Within cargo and ballastWithin cargo and ballast

tankstanksItemItem

ExtenExten

ttBottom and side shell (up to Bottom and side shell (up to limit of wetted area)limit of wetted area)Bilge areaBilge area andand side shell side shell (up to limit of wetted (up to limit of wetted

Additional LugsAdditional Lugs

AdditionalAdditional BktsBkts

area)area)



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s Green SeasGreen Seas

�� RuleRulerequirementsrequirements

�� Model testingModel testing�� PressuresPressures�� BreakwaterBreakwater�� DrainageDrainage

typtyp..

88 -- 14m14m

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s Bottom SlammingBottom Slamming



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s Sloshing in Cargo Oil TanksSloshing in Cargo Oil Tanks

�� Tank SizeTank Size�� Hull formHull form�� EnvironmentEnvironment�� Natural PeriodsNatural Periods�� LR FLUIDSLR FLUIDS

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s Typical Hull Protection SystemTypical Hull Protection System

HighHighperformanceperformance

coatingcoating

High performance coating + High performance coating + cathodiccathodic protection systemprotection system

WaterWaterballastballastMax. W.L.Max. W.L.

Min. W.L.Min. W.L.

HPCHPC++

SASA

HPCHPC

CoatingCoating

NB : ImpressedNB : Impressedcurrent system current system not allowed innot allowed inCargo oilCargo oiltankstanksCoatingCoating



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sFabrication Tolerances and WeldingFabrication Tolerances and Welding

� tolerances should be in accordance with good shipbuilding practice, and agreed with LR

� special attention given to fatigue sensitive areas

� enhanced NDE levels will be necessary for identified fatigue sensitive areas

� assumptions used in analytical fatigue assessments to be consistent with construction

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s NDE Testing of Welds NDE Testing of Welds -- generalgeneral

�� Intersection of butts and seams & section weldsIntersection of butts and seams & section welds�� Butt welds in platingButt welds in plating�� Seam welds in platingSeam welds in plating�� Bilge keel buttsBilge keel butts�� Structural items fabricated with full/part penetration Structural items fabricated with full/part penetration

weldingwelding (hopper knuckles, (hopper knuckles, sheerstrake, hatchway coamings)�� Penetrations & attachments to hull Penetrations & attachments to hull (sea inlets, piping, anode (sea inlets, piping, anode

supports)supports)�� MoonpoolMoonpool integration structureintegration structure�� Topside support structure connections to hull structureTopside support structure connections to hull structure�� Additional requirements for low temperature operationsAdditional requirements for low temperature operations



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FPSO some In-service feedback

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FF1FF1--3c3c

Some Design Life IssuesSome Design Life Issues

� Holistic approach for project / good communications

� Design for required service� Compatibility of hull structural, systems and

topsides interfaces� Production equipment for required service� Marine equipment robustness, particularly

cargo/ballast and control/electrical systems� OIWS requirements and corrosion protection� Access arrangements� Provision of spare parts



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s DesignDesign-- Frequent areas of concernFrequent areas of concern� Marine/offshore regulations and practices� Topsides structure supports (alignment, motions)� Hull vibration� Crane specification and integration with hull� Corrosion - general� Access and escape routes compatibility� Hazardous area and classification interfaces� Piping systems (compatibility/flexibility)� Topside equipment / motions / helicopter operations� Marine / Topside system integration� Use of GRP / FRP, pipework etc� Wave impact and green sea loading� Rudder and steering gear� Laydown areas� Effect of exhaust (heli-operations)

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s Design Issues Design Issues -- InterfacesInterfaces�� Interface Management is a critical influence on Interface Management is a critical influence on

project successproject success�� LR Project Manager provides interface between LR Project Manager provides interface between

design and class/certification processesdesign and class/certification processes�� Technical interfaces to be developed include:Technical interfaces to be developed include:

�� Escape and access routingEscape and access routing�� Hazardous area definitionHazardous area definition�� Venting arrangements (clear of hazardous areas and for inspectioVenting arrangements (clear of hazardous areas and for inspectionn

activities)activities)�� Power generation and supply systems, normal and backupPower generation and supply systems, normal and backup�� BundingBunding/prevention of spillage to main deck/prevention of spillage to main deck�� Control System and alarm circuitsControl System and alarm circuits�� Crude oil pumping and piping system between vessel, process and Crude oil pumping and piping system between vessel, process and

offloading systems, including materialsoffloading systems, including materials�� Fire Water, Cooling and Injection Water Fire Water, Cooling and Injection Water �� Heating system, Compressed air supplyHeating system, Compressed air supply�� Topsides structure alignment at integration with deckTopsides structure alignment at integration with deck�� Deck crane integration with hull structureDeck crane integration with hull structure�� Mooring system integration with hull structureMooring system integration with hull structure



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s Structural InspectionStructural Inspection

�� Carried out on locationCarried out on location�� Provides detection / monitoring Provides detection / monitoring

capacitycapacity�� Annual, intermediate & major Annual, intermediate & major

surveyssurveys�� Major survey (5 years or continuous)Major survey (5 years or continuous)�� IWS in lieu of dry dockingIWS in lieu of dry docking�� Internal surveyInternal survey

�� cleaning & gas freeingcleaning & gas freeing�� access arrangements/safetyaccess arrangements/safety�� lighting/ventilationlighting/ventilation�� loading conditionsloading conditions

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s FPSO Incident History ExamplesFPSO Incident History Examples

� Hull Structure� Shuttle tanker collision� Bow Wave Impact Damage� Tank Overpressurisation� Seawater caisson

preferential Corrosion� Integration of surface and

subsea corrosion protection� Rudder/steering gear

� Marine Equipment� Corrosion in cooling and

heating systems due to poor fluid chemistry control

� Material problems on seawater systems

�� TopsidesTopsides�� Vibration induced failuresVibration induced failures�� Inadequate application of Inadequate application of

PFPPFP�� Gas Turbine problemsGas Turbine problems�� Produced Water Produced Water

CorrosionCorrosion�� Damage due to wave Damage due to wave

impact (green water)impact (green water)�� Cargo Venting System Cargo Venting System

failurefailure�� Pipework and Production Pipework and Production

Train LeakageTrain Leakage�� Riser / turret connectionsRiser / turret connections



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s FPSO Incident HistoryFPSO Incident HistoryStatistics (Reported)Statistics (Reported)

Ref : 22 vessels, approx 10 years of recordsRef : 22 vessels, approx 10 years of recordsSee also See also Quantified Frequency of shuttle tanker collision during offtake Quantified Frequency of shuttle tanker collision during offtake operationsoperations, IMCA, IMCA

VesselSystem

Nature of Incident No. ofIncidents

Hull Structure failure in heavy weather 1Other structural failure 3Collision 6

Topsides Structural failure in heavy weather 3Process equipment failure 2Fire 0

Machinery Engine Room fire 2Engine Room power failure 1Main engine failure 1Rudder / steering gear failure 3

Other Hydrocarbon release 2Explosions 0Loss of anchor(s) 1

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s Vibration Damage Vibration Damage �� flare stackflare stackVortex vibrations @ Beaufort 4 Vortex vibrations @ Beaufort 4 -- 55

View A

View B

View A

View B

Turret Deckhouse

Brace on Port Side -cracked over 180o atconnection to forward chord.

Proposedreinforcements - twolateral braces.



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s Mooring System InstallationMooring System Installation� Problems Experienced

� Handling equipment failures� Wire ropes

�Poor tension control�Loops formed�Bird caging

� Chains�Lack of straightness�Installed with twist�Tangles & breakage

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s Results from a Structural SurveyResults from a Structural Survey

Example of DefectExample of DefectAreaAreashownshown

Cargo/ballast tanksCargo/ballast tanks DefectDefect

B B B B

LocationsLocationson Side Shellon Side Shell

B B B



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s Typical DamageTypical DamageSide shell longitudinal connectionSide shell longitudinal connection

CrackCrack

CrackCrack

ShellShelllongitudinallongitudinal

ShellShellplatingplating

Face barFace bar

Web frameWeb framestiffenerstiffener

Broken weldingBroken welding

Web frameWeb frame

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s Examples of Internal Welded Examples of Internal Welded RepairsRepairs

Side shellSide shell BulkheadBulkheadstiffenerstiffener

Side longitudinalSide longitudinal

FractureFracturelocationslocations

TransverseTransversebulkheadbulkhead

StiffenerStiffener

Side shellSide shell PillarPillarstiffenerstiffener

Additional lugAdditional lug

Backing bracketBacking bracket

Side shellSide shell

SideSidelongitudinlongitudin

alal

NewNewlongitudinallongitudinal

sectionsection

BulkheadBulkheadstiffenerstiffener

Transverse bulkheadTransverse bulkhead

AdditionalAdditionalradius bracketradius bracket

Stiffener withStiffener withsoft toesoft toe



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s Internal Repair Internal Repair -- NonNon--WeldedWelded

Hole drilled at crack Hole drilled at crack terminationtermination

Bolted platesBolted plates

StiffenerStiffener

FrameFrame

LongitudinalLongitudinal FacingFacingplateplate

CrackCracklengthlength

TransverseTransverseweb frameweb frame

CrackCrack

Local weld GrindingLocal weld GrindingSection of hullSection of hullExternal girder External girder

reinforcementreinforcement

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End of LREnd of LRPresentationPresentation


Documents

Tanker Conversions to FPSO