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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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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