Damien Thiery
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Transcript of Damien Thiery
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Converted tankers into FPSO:Life extensions structural challenges
Damien THIERYOffshore Project Engineer
Bureau Veritas HO [email protected]
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2MCE Deepwater Development 2014 - Madrid
Introduction: converted tankers into FPSO
In 2014: Conversions represent approximately 70%of the F(P)SO units
Forecast of F(P)SO orders over the next period (2014-2018):
Conversion 55% New built 25%
Redeployment 20 %
2 phases should be taken into account:
Life extension: when the asset exceeds its design life
Tanker Service
FP(S)O Service
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3MCE Deepwater Development 2014 - Madrid
Contents
1. Hull structure challenges
2. Structural analysis
Strength assessment
Fatigue assessment
3. Integrity management System
4. Conclusion
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4MCE Deepwater Development 2014 - Madrid
Hull structural challenges
Previous history: as trading services and during the transit
RAO Roll RAO Pitch
RAO Roll
RAO Pitch
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5MCE Deepwater Development 2014 - Madrid
Hull structural challenges: Tanker service
What are the main hull degradation processes of a tanker ?
Corrosion
Fatigue cracks / fatigue accumulated damage
What is the current hull condition ?
Is the operating history (log book) fully known ?
Are previous inspection / repair reports available ?
Which is the outcome from the condition assessment survey (corrosion) ?
How site environmental conditions compare with tanker class notation ?
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6MCE Deepwater Development 2014 - Madrid
Hull structural challenges: FPSO Service
How to ensure the hull is eligible to be converted ?
Which are the results of feasibility study and in terms of strength and fatigue ?
Design conversion verification by structural assessment: forecast futurecondition and expected end of life.
What are the necessary repairs to face the FPSO service life ? IMR strategy to be defined in order to ensure the operational continuity
Is there an Asset Integrity Management System planed ?
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7MCE Deepwater Development 2014 - Madrid
Structural Analysis
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8MCE Deepwater Development 2014 - Madrid
Structural Analysis
Input for the structural analyses :
Key structure drawings
Capacity plan
Trim & stability booklet
Weight distribution
Tanker speed and trading routes history
Towing/transit speed and route
Repair history, detected failures, damages, particular findings:cracks, indents, impacts, pitting,
Corrosion as is condition or reassessed scantlings
FPSO operational Loading conditions, Loading/Unloading
sequence Site metocean conditions
Hydrodynamics & heading analysis results
Mooring analysis results (mooring loads at hull interface)
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9MCE Deepwater Development 2014 - Madrid
Structural Analysis: Strength analysis
FINDINGS
Strength analysis
Design waves applied on the model to maximize loadparameters.
Yielding verification Buckling verification
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10MCE Deepwater Development 2014 - Madrid
Structural Analysis: Fatigue analysis
Fatigue analysis
Operational loading condition + transit condition
Assessment of typical locations (determined by experience & fatigue scan)
Analysis of previously detected cracks on board Assessment of repair solutions
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11MCE Deepwater Development 2014 - Madrid
Structural Analysis: Particular areas
Turret-Hull Interface
Crane Pedestals
Topsides stools
Hopper knuckle
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12MCE Deepwater Development 2014 - Madrid
Structural Analysis
Outputs of structural analysis
Remaining life assessment
Inspection plan definition based on hot spot maps
Determination of repair/modification solution To avoid further cracking
To insure sufficient corrosion margin
To avoid integrity issues resulting in production down time
To avoid hot work or dry dock
Area 1
Area 3Area 2
Area 4
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13MCE Deepwater Development 2014 - Madrid
Integrity management System
Operator & Partners
ensuring that FPSO inspection plan is carried out and updated with documents
(modifications, inspection findings, corrective actions )
Marine operation
department
Project TeamInspection Plan
Production
department
Contractor
Site inspectors
Safety
department
Maintenance
department
Classification Society
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14MCE Deepwater Development 2014 - Madrid
Conclusion
Corrosion and structural integrity are the main challenges
Finite Elements Analyses and Asset Integrity Systemprovide answers regarding :
The status of the hull structure = condition assessment If the unit is suitable for intended = life extension
How to anticipate / minimize / avoid offshore structural work beforegoing offshore
Follow-up in service (Class surveys, operator inspections)
Tanker service
Trading routes Damages and repairs
Surveys
Structural analysis
FPSO service
Sites conditions Expected service life
Structural analysis
Inspection & Maintenance
CONVERSION
