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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)
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
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
s Hull Selection Issues (conversion)Hull Selection Issues (conversion)�� Vessel age, condition and service historyVessel age, condition and service history
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)
Tanker Conversions to FPSOs - Rob Potthurst, Lloyd’s Register ()
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
Tanker Conversions to FPSOs - Rob Potthurst, Lloyd’s Register ()
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
Tanker Conversions to FPSOs - Rob Potthurst, Lloyd’s Register ()
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
Tanker Conversions to FPSOs - Rob Potthurst, Lloyd’s Register ()
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
Tanker Conversions to FPSOs - Rob Potthurst, Lloyd’s Register ()
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
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)
Tanker Conversions to FPSOs - Rob Potthurst, Lloyd’s Register ()
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
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
Tanker Conversions to FPSOs - Rob Potthurst, Lloyd’s Register ()
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
Tanker Conversions to FPSOs - Rob Potthurst, Lloyd’s Register ()
�� 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
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