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REPAIR, MAINTENANCE&
LIFEEXTENSION SOLUTIONS(RMLES)
FOR OFFSHOREPLATFORMJACKETS
BY ZOEY LIM
Field Life Extension Through Asset Integrity 2013 Asset Integrity Forum
Date : 18thSept 2013
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www.iev-group.com
CONTENTS
1. The Initiators
2. Systematic Approach
3. Structural Assessment
4. Basic Approaches
5. Selection Criteria
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THE INITIATORS
Damaged Structures
Fatigue loads
Vessel collision
Dropped objects
Corrosion
Damage during installation
Welding or fabrication fault
Explosions
Under-design
Common Damages :Dents, bows, cracks, tears,
permanent deformation, holes,
loss of thickness, etc .
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Intact Structures
Change in Platform Operation
Placement of additional equipment
Development of marginal or satellite fields using subsea systems
Enhanced Oil Recovery Program
Recertification of offshore structures Change of Industry Codes
In particular for structures in service beyond its originally designed
service life.
Increased Safety Measures
THE INITIATORS (cont.)
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SYSTEMATIC APPROACH
Initiators of RMLES
Structural Analysis Global
and Refined Local Analysis
SUBSTRUCTUREINSPECTION DATA
OTHER INPUT DATA
Ph. 1 Substructure Survey
Structure OK
Proposed RMLES Scheme &
Methodology
Ph. 3 RMLES Selection
Further Structural Analysis
& 3rdParty Approval
NG
Ph. 2 Structural Analysis
Detailed Engineering and
Preparation
Offshore Installation
Planning
Execution & Documentation
Ph. 4 Design & Preparation
3rdParty Inspection &
Approval
Ph. 5 Execution
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STRUCTURAL ASSESSMENT
Global analysis using updated loading, structural and
environmental conditions including in-place analysis,
push over, unity check of members and nodes
Local analysis of
nodes where defectsare identified
Fatigue analysis
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REDUCE LOADINGS
Removal of redundant equipment from topside
Wave Zone Clean-up Removal of unused/redundant structures in the splash zone area
Marine Growth Removal
Marine Growth Control Technology
(permanent) High pressure water jetting (periodic)
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REPAIR DAMAGES
Dented/Bowed
Member
Non-fatigue
CrackFatigue CrackCorrosion
Tubular
Grouting
Weld doubler
plates over
dent Member
replacement
Weld Patch
Plates
Grouted sleeve
Member
replacement
Anodereplacement if
due to anode
depletion
Splash zone
coating
Weld gussets
Grouted
clamps or
sleeves
Underwaterdry welding
Remedial
Grinding
Underwater
dry welding
Weld gussets
Grouted
clamps orsleeves
Remedial
Grinding
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LOCAL STRENGTHENING
Insufficient Fatigue Life
Weld improvement by modification
Insufficient Structural Capacity Underwater Dry Welding to install doubler plates or sleeves
Clamping methods Tubular grouting
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GLOBAL STRENGTHENING
Create alternate load paths by introducingnew members connected using :
Dry Welding
Clamps
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SELECTION CRITERIA
Life extension requirements for the installation
Technical Performance & Reliability
Costs
Water Depth
Offshore support & Equipment requirements
Timescale of each phase
Availability of local resources
Tolerance acceptability
Existing applications & Knowledge
Environmental & Safety requirements
Post execution inspection requirements
Potential challenges for each phase
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Thank you