design appraisal for offshore structures

Lloyd’s Register services to the energy industry

November 11-14, 2012 Adipec

Yeramilli Srinivas

Lead structural engineer

Design Appraisal for Offshore Structures



Design Appraisal Methods

• Design Appraisal by review of client design reports

• Design Appraisal by Independent analysis



Design appraisal types

• VERIFICATION WITHIN A REGULATORTY FRAME WORK

• THIRD PARTY COMPLIANCE REVIEW

• CERTIFICATE OF FITNESS (COP)



VERIFICATION

• Purpose: to safeguard personnel by avoiding major accidents

• Scheme operated by Duty Holder

• Safety Case

• SCE’s

• Performance Requirements/standards

• Verification/suitability Statement



3rd Party Compliance Review

• Purpose: to undertake an agreed scope of design review.

• Scope defined by Client

• Assessed to client specification

• LR DAD or Report.



Certificate of Fitness (CoF)

• Purpose: to ensure the integrity of the installation

• Scheme operated by LR on behalf of Regulator

• Standards and Regulatory requirements

• Design Review + Offshore Survey

• Certificate of Fitness



Design appraisal of the following structures

• Fixed offshore jacket

• Topside structures

• Tripod systems and bridges

• Near shore structures such as jetties



Design appraisal for inplace conditions for verification

• Inplace Analysis

• Fatigue Analysis

• Earthquake Analysis

• Boat Impact analysis

• Blast Analysis

• Push over analysis



Software's used for independent analysis

• SACS – Structural analysis computer system

• STAAD PRO – Structural analysis software

• USFOS – for non-linear Analysis



Design appraisal for installation conditions for third party review jobs• Loadout

• Sea Transportation

• Lift

• Upend

• On-bottom stability

• Docking



Design Appraisal of Life extension of platforms

• Design appraisal by Review of documents

• Design appraisal by independent analysis



Primary Documents required for Review

• Up to date weight control report

• Up to date metocean report

• Geotechnical report

• Up to date inspection reports of platforms for scour depths , member damage , corrosion , marine growth and fatigue cracks , CP measurements.



Primary Analysis required for review for life extension

• Inplace analysis

• Fatigue analysis

• Ship Impact analysis

• Redundancy analysis

• Push over anlysis



Design appraisal flow chart

Documents/Drawings, asidentified by LR, issued at AFDand submitted by Designers

LR comments/approval,including status, submitted ona Comment Response Sheet

(CRS)

Designer accepts or providesadditional comments

Designer responds on CRSLR closes out CRS or reviews

additional comments

New CRS cycle if required

Closed-out CRS passed to SiteSurveyor to check that any

changes have beenincorporated in Site Drawings

LR Design Team reviewdocuments

CRS Closed outApprovedComment

design appraisal for offshore structures

Technology