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Risk based Asset Integrity Management (RAIM)
1. Risk based Asset Integrity Management (RAIM) - Overview2. What is Risk based Asset Integrity Management
3. Risk Based Integrity Management procedure
4. Risk-Ranking of Structure Qualitative
5. Probability of Failure Categorisation
6. Consequence of Failure Categorisation
7. Risk Ranking Quantitative8. Risk based design
9. Risk based inspection
10. Risk based repair -- Cost-Benefit Analysis
11. Analysis Types
12. Structural Failure Probability Calculation for Storm Case13. General Structural Failure Probability Calculation
14. Progressive Collapse Analysis
15. Ship Impact Analysis
16. Typical FE analysis For a Semi sub Global Model
17. Fine mesh FE model for the critical central K node
18. Fine mesh FE model for Pontoon column intersection19. Solid FE model of tubular joint
20. Corrosion/Strength: Probabilistic Methods
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Risk based Asset Integrity Management (RAIM) -
Overview
Risk based Asset Integrity Management (RAIM) -
Overview
Asset Integrity
Management
Risk Based
Design
Condition
Assessment
Inspection Planning
Asset
Replacement
Planning
Remnant Life
Fitness for Purpose
Extended Life
On-line Monitoring
Strong Vibration
Risk Based Inspection Planning
Inspection Scheduling
Risk centered
maintenance
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What is Risk based Asset Integrity
Management An integrated service that considers all facets of a facility or
installation to establish, manage and optimize the through liferisk profile.
Risk based design
Risk based inspection
Risk based repair
Risk centered maintenance
Benefit
Optimise total cost of maintenance
Quantification of risk levels
Reduce disruption to operations
Supports Asset change of use / life extension / resale
Long term reliability, safety and reduced operating cost
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Risk Based Integrity Management
procedure
Reliability
Prediction
Statistical
Analysis
Inspection/FR
Data
FE Analysis
Fracture/Fatigue
Assessment
Risk Ranking
Mitigation
Analysis
System/Design
Modelling
Hazard I.D. & Analysis
FTA/FMEA/CCA
HAZOP/FFA
Definitions
Severity
Categories
Likelihood Categories
Safety
Criteria/Req/Rules
Inspection, Replacement, Corrosion
Management Schemes Operation controls, Redesign
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Determine Consequenceof FailureDetermine Likelihood ofStructural Failure
Structure
Consequence
Likelihood
of
failure
Risk-Ranking of Structure - QualitativeRisk-Ranking of Structure - Qualitative
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Probability of Failure Categorisation
Cat Annual Probability Description
Quantitative Event Team Experience
5 >10-2 Almost certain The event could
occur at some time
The team know several
occurrence in recent
months
4 10-3 to 10-2 probable The event could
occur at some time
It is a occurrence in the
industry in the last year.
3 10-4 to 10-3 Possible The event could
occur at some time
The team know a few
occurrence but not in the
last few years
2 10-5 to 10-4 Unlikely The event could
occur at some time
Only few occurrence are
known of in the experiences
of the team
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Consequence of Failure Categorisation
Consequence of
FailureMember
characteristicsAsset loss
Business
interruptionSafety
Environment damage
Cat Qualitative General
5 catastrophe
Essential members
to the integrity of the
system
Extensive damage
>100 million USD100 days
Multiple fatality (or
permanent total
disabilities)
Massive effect, large scale (10
100 mile2) long term impact
4 Major
Essential members
to the operational
performance of the
system
Major damage 10
-100 million USD10 days
1 fatality (or
permanent total
disability)
major effect, medium scale (1 10
mile2) medium term impact (years)
3 Considerable
Non-Essential
members but failure
can impede theperformance of the
system.
Local damage 1-
10 million USD 3 days
Major injury /illness,
permanent partial
disability or lost time
injury (>4 days)
Local effect, medium scale (1 10
mile2) medium term impact(months),
2 significantRedundant member
through mitigation
Minor damage 0.1
- 1 million USD1 day
Minor injury/illness,
restricted duties or lost
time injury (
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Risk Ranking Quantitative
Consequence of failure
Probabilistic fracture mechanics includingfatigue, corrosion, POD, etc.
Extreme statistics analysis
Final fracture or collapse probability
Failure frequency, QRA, HAZOP
Production lossContractual penalty
Negative publicity
Cost of repairing
Threat to public health, environment
Probability of failure
Probability of failure
Low Moderate High
Consequence
of failure
High
Moderate
Low
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Risk based designRisk based design
Most of current offshore standards set the probability of failure to be
between 10-5 and 10-4
Codes and standards are based on generic cases
Risk based design can be used Probability of failure is based on specific case hence more economic
Develop Safety factors for specific site condition to achieve the same level of risk as in
standards
Calculate the level of risk for investment decisions
Risk reduction --- lower overall risks with the same investment
Cost reduction -- efficient use of resources for the same target risk level
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Risk based inspectionRisk based inspection
Risk Based Inspection (RBI) uses risk techniques to focus inspection
resources, as part of AIMS
The RBI process defines
where to inspect More inspection on higher risk items Less inspection on low risk items
when to inspect Time interval based on risk prediction
how to inspect
It is updateable based upon inspection findings
It is an ongoing process used throughout the life cycle of the facility
RBI Benefit
Risk reduction --- lower overall risks with the same inspection resources Cost reduction -- efficient use of inspection resources for the same target
risk level
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Risk based Repair -- Cost-Benefit Analysis
1. Assessment of differentremediation options to
determine most optimal
action
2. Focused on capital and
revenue protection RemediationCost
Remediation Alternative
Cost
Do nothing Do everything
Total Cost
Failure
Cost
Optimal
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Analysis Types
1. Linear analysis for ULS, FLS code checking
2. Structural failure probability analysis3. Non-linear Progressive Collapse (push over) Analysis
4. Finite Element Analysis
5. Advanced Fatigue Analysis
6. Fracture Mechanics
7. Corrosion Engineering
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Structural Failure Probability Calculation
for Storm Case
- Quantitative
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General Structural Failure Probability
Calculation
Requiring Pushover analysis to
determine failure
Best estimates applied for allquantities
Uncertainties represented
explicitly
FE analysis may be required
Total risk can be reduced through
1. Load Reduction
2. Strengthening
3. Reduction in uncertainties
Failure Probability Calculation
Value
Frequency
Mean Load Mean Resistance
Load Resistance
RRS S
Reserve Strength
Failure
Failure Probability Calculation
Value
Frequency
Mean Load Mean Resistance
Load Resistance
RRS S
Reserve Strength
Failure
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Progressive Collapse Analysis for Design
Against FireNon-linear structural response analysis is
used in fire response analysis to consider
thermal expansion effects, the degradation of
material strength with increased temperature,and the structural progressive collapse under
fire.
The results of advanced fire response analysismay be used to develop an optimised scheme
of passive fire protection for the structure.
Potential savings for a typical offshore
structure are in the range of 50% of theoriginal scope
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Ship Impact Analysis
Conventional single member analyses onlyutilise the energy dissipating capacity of theimpacted member.
The progressive collapse analysis takes intoaccount all the energy dissipation mechanismsand therefore is able to provide a more realistic
estimate of the resistance (or survivability) ofthe platform to ship collision. Thus a moreoptimal design or more realistic risk assessmentcan be achieved.
Utilising advanced analysis, a number of impactscenarios can be analysed quickly. This isespecially useful at the design stage.
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Typical FE analysis For a Semi sub Global
Model
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Fine mesh FE model for the critical central
K node
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Fine mesh FE model for Pontoon column
intersection
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Solid FE model of tubular joint
Tubulars are modelled with solid
brick elements in several layers
across the thickness for accurate
determination of local hot spotstresses
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T y p ic a l L o g - N o r m a l C o r ro s i o n R a t e D is t r i b u t io n
0
2
4
6
8
1 0
1 2
0 .0 0 .1 0 .2 0 .3 0 .4 0 .5 0 .6
C o r r o s i o n R a t e (m m /y e a r )
Probabilit
yDensityFunction
M a x . V a lu e
( 9 5 % o f N o n - Ex c e e d a n c e )
M in . V a l u e
( 5 % o f N o n - Ex c e e d a n c e )
Corrosion/Strength: Probabilistic Methods
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