Structural Integrity Management and Risk Based Inspection – Recent Developments

G. Abdel Ghoneim, Ph.D., P.E.08 December 2009

Structural Integrity Management and Risk Based Inspection Recent DevelopmentsSNAME Texas Section Meeting

Det Norske Veritas AS. All rights reserved.

SIM and RBI Recent Developments

SNAME Texas Section Meeting, 08 December 2009

2

Agenda

Introduction Gulf of Mexico Activity SIM and RBI Fundamentals Recent Standards Challenges Summary




309 December 2009

GOM Platform Activity

Source: MMS0

100

200

300

400

500

600

700

800

900

400

WaterDepth(ft)

N

o

.

o

f

S

t

r

u

c

t

u

r

e

s

19451972

19731982

19832009

Source: MMS, B.J. Kruse, III




4

GOM Platform Decommissioning

GoM Platform Vintage (Years)

15%

25%

30%

30%

30

Total ~ 3,900 Platforms

Average Removal Age ~ 16 years

Source: MMS, B.J. Kruse, III, K. S. Patterson, WISTA Oct 2008




5

The Issues

Source: O'Connor, BP, M. Lalani, June 2007




6

API RPs and Guidelines API 2A-WSD, Recommended Practice for Planning Designing and Constructing Fixed

Offshore Platforms Working Stress Design.

API 2A-LRFD, Recommended Practice for Planning Designing and Constructing Fixed Offshore Platforms Load and Resistance Factor Design.

API Bulletin 2TD, Guidelines for Tie-downs on Offshore Production Structures for Hurricane Season.

API 2T, Recommended Practice for Planning Designing and Constructing Tension Leg Platforms.

API 2FPS, Recommended Practice for Planning Designing and Constructing Floating Production Systems.

API 2SK, Recommended Practice Design and Analysis of Stationkeeping Systems for Floating Structures.

API 2RD, Recommended Practice Design of Risers for Floating Production Systems (FPSs) and Tension-Leg Platforms (TLPs).

API 2I, Recommended Practice In-Service Inspection of Mooring Hardware for Floating Drilling Units.




7

API 2HINS Inspection Initiator Process




8

Destroyed GoM Platforms

2 3

148

3 2 3 3

40

7 7

47

69

2

60

0

10

20

30

40

50

60

70

80

1948 1961 1964 1965 1969 1974 1979 1985 1992 2002 2004 2005 2005 2008 2008

Year

N

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m

b

e

r

o

f

P

l

a

t

f

o

r

m

s

D

e

s

t

r

o

y

e

d

2.00E-04

1.00E-03

5.00E-04

1.00E-03

5.00E-044.00E-04

1.00E-050.00E+00

2.00E-04

4.00E-04

6.00E-04

8.00E-04

1.00E-03

1.20E-03

Stiff, 2009 Stiff, 2009 Stahl, et.al.,2000

THIC, 1992 Stahl, 1986 ISO 19901-2,2004

ISO 19902,2008

Source

A

n

n

u

a

l

F

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P

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a

b

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y

SRRSR =

100SRRSR =



SNAME Texas Section Meeting, 08 December 2009 9

Platform Structural AnalysisLoad exposure




10

Safety format (LRFD vs. WSD)

FactorResistance

Load and Resistance

P

r

o

b

a

b

i

l

i

t

y

D

e

n

s

i

t

y

MeanLoad

MeanResistance

FactorLoad

CharacteristicResistanceLoad

Characteristic

Requirement Rd




11

SIM Process

Management of Change

CompanyPolicy

Reporting and Communication

InformationManagement

Organization andPersonnel

Audits andReviews

ContingencyPlans

SIM Process

Develop Integrity Management Plan (IMP) forStructure / System

Implement IMP for theStructure / System

Learning and Improvement

Hazard Evaluation andRisk Assessment



SNAME Texas Section Meeting, 08 December 2009 Slide 12

Principles of Asset Integrity Management Integrity management life cycle activities

Evaluate Risk

Maintain

Inspect

Monitor Integrity

Plan survey

InspectRecordfindings

Evaluate findings

Filter findings

Assess risk(incl. SRS)

Update risk status Update overall

inspection plan

Plan follow upactions

Do follow-up actions

Integrity

FindingsActions

Inspection plan

12




13WCT

Seminar April 26,

Why SIM - Ageing Problem? The contribution of structural failure to the total number of historic

accidents is less than 10% based on worldwide data (Kvitrud, et. al., 2001).

The reliability of a structure against environmental loads may become unacceptable in extended lifetime. Subsidence, degradation and changes to the original design may occur at a higher rate in extended platform life.

Lack of data on the structure (e.g. drawings, steel type, welding procedures, inspection results and details about earlier repairs etc.) may result in higher uncertainty.

Using a systematic approach for evaluating whether a structure is safe for use beyond its initial design life, taking the above mentioned issues into account, is the objective of SIMS.

The SIM system has proven invaluable even for relatively newer structures both fixed and floating.

Ersdal, G. Ph.D. Thesis, U of Stavanger, October 2005




14

Ageing & Need for SIM & RBI




15

What is Risk-Based Inspection (RBI)?

Strategic process for lowering risk and lowering cost An integrated, data-based methodology that factors risk into inspection

decision making

Risk analysis includes not only probability of failure (PoF) but also consequence of failure (CoF)

A qualitative and quantitative process for managing structurres/equipment based on risk analysis

A systematic process that establishes and prioritises risk levels for each component in the structure

RBI is an important element in the SIM system.




16

Input data

Condition Evaluation

Action plans

Observations

Events / History

Inspection results

MonitoringAnalyses / (re-)design

Condition evaluations(sections and components)

Activities plan Inspection plan

Inspections

Monitoring results

Operating req. & limits

ORBIT : Main principles




17

Terminology Robustness RSR Push-over/Time-domain Assessment/Re-assesment Risk/Reliability RBI Design Life Standards/Regulations Limit States WSD/ASD and LRFD Design Criteria Joint Flexibility SRS Load Factor

Fatigue/Fracture Failure Safety Category Consequence of Failure Category Strength Hazards Acceptability Criteria Air Gap Wave-in-Deck Probabilistic Methods Bayesian Approach Degradation Fitness-for-purpose SIMS Bias




18

The Two Main Steps of RBI

Expected RISK Cost

0

1

2

3

4

5

6

1.0E-04 1.0E-03 1.0E-02 1.0E-01Target Failure Probability Level

N

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E

x

p

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C

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Expected Inspection CostExpected Failure Cost

Expected Repair CostTotal Expected Risk Cost




19

Key Concepts

The Key Concepts of RBI

RISK = Probability of Failure XConsequence of

FailureGFF Item DFX

Age

Damagetype/rate

Insp.effective.

Damage areaItem repair

Other repairsInjury

Business int.Env. clean up




20

Consequence models estimate:- Heat radiation levels from fires- Gas dispersion distances- Durations of fires- Explosion pressures- Number of fatalities per accident- Environmental effect




21

Reducing Risk

Inspection frequencies Inspection scope / thoroughness Inspection tools / techniques Inspection practices (internal vs. external) Building more Redundancies Maintenance Proper use/understanding the limitations Emergency response Trained crew Effective communication lines Local knowledge




22

Marine Safety Regulations

Classification Societies

Rules

Rules

Classification of Mobile Offshore Units

Formal Safety Assessment

Step 1 HazardIdentification

Step 2Risk

Assessment

Step 5Decision Making

Recommendations

Step 3Risk Control Options

Step 4Cost Benefit Assessment

International Maritime

Organization

MODU Code




23

Risk Assessment Hazard review

Hazard checklist

HAZOP (hazard and operability study)

FMECA (failure modes, effects and criticality analysis)

SWIFT (structured what-if analysis)

Risk matrices

Risk ranking

Structured judgement




24

Risk Assessment

Major accident

Controls

THREATS CONSEQUENCES

Accident Scenario

Management System

Fault trees

Event trees

Bow tie diagrams

Rules and standards

Engineering judgement

Risk criteria

Cost-benefit analysis

Company values

Unacceptableregion

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Tolerableregion

Broadly acceptableregion




25

Quantitative Methods

Weather Outcome

Severe 50% fatalities0.01

Rough 30% fatalities0.09

Evacuation1.0E-04 Moderate 10% fatalitiesper year 0.4

Calm 5% fatalities0.5

Severe5%

Rough28%

Moderate41%

Calm26%

Historical data analysis

Fault tree analysis

Event tree analysis

Consequence modelling

Evacuation modelling

Risks and uncertainties




26

Influences on Technique Selection

Decision context

Lifecycle stage

Major hazard potential

Novelty/non-standard

Uncertainty

Views/perceptions

Techniques

Practicality

Strengths and weaknesses

Good practice

Efficiency




27

Traditional Inspection Planning vs. RBI Planning

Traditional

Inspection based on experience (usually by previous failures/breakdowns)

Inspection effort driven by likelihood of failure

Reactive fire fighting, running behind the ball

Use of appropriate / Inappropriate NDT techniques

RBI

Inspection based on experience andsystematic (risk) review

Inspection effort driven by risk, i.e. likelihood of failure and consequences of failure

Pro-active planning and execution of inspections

Systematic identification of appropriate NDT techniques




28

Suitable and Sufficient Inspection Planning

Suitable techniques appropriate for the assessment being made

Sufficient adequate to show the risks are ALARP, without requiring further elaboration

S in g le co m p o n e n t co n sid d e re d ; D e sig n l ive = 20 y r

1 .0E-06

1 .0E-05

1 .0E-04

1 .0E-03

1 .0E-02

0 2 4 6 8 10 12 14 16 18 20S e rv ic e tim e in y e a rs

F

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29

RBI Investment and Savings

$400,000

$65,000$85,000$50,000

$500,000

$675,000

$250,000

$550,000$600,000

$0$100,000$200,000$300,000$400,000$500,000$600,000$700,000$800,000

Total $ Savings = $1.1MROI = 22:1

RBIStudyInvest

Inspect& MaintSavings

ProdCost

Savings

RBIStudyInvest


ProdCost

Savings

RBIStudyInvest


ProdCost

Savings

Total $ Savings = $650,000ROI = 8:1


Chemical Plant Chemical Plant -- 200200Pressure VesselsPressure Vessels

Refinery Refinery -- 3535Pressure VesselsPressure Vessels





30

$100,000$200,000$300,000$400,000$500,000$600,000$700,000$800,000

$65,000$50,000

$500,000

$675,000

$75,000

$550,000$600,000

$0


RBIStudyInvest


ProdCost

Savings

RBIStudyInvest


ProdCost

Savings

RBIStudyInvest


ProdCost

Savings



Chemical Plant Chemical Plant -- 200200Pressure VesselsPressure Vessels

Offshore InstallationOffshore InstallationPiping & VesselsPiping & Vessels


$1,520,000

rbi invesment & savings

Typical ROI = 8:1




31

ORBIT Structure




32

RBI Detailed Assessment




33

RBI Detailed Assessment




34

Inspection PlanningChallenges: No general standard, guideline or common industry practice available

for inspection planning for structures

SIMS

RBI analysis

ORBIT/Profast

RBI analysis report

Member condition Inspection history

Updated Master RBI Table- RBI Input and results

Inspection plan (FIPs)

RBI Analysis Process

SIMS FIPs Upload

Orbit Workflow ManagerOrbit Workflow Manager

New fatigue analysis results

Updated FIPs

(input and results)

Master RBI Table (2004)- Fatigue point identification - fatigue damage rates - Analysis Method Fatigue- Analysis Method Collapse- consequence of member failure- preferred inspection method- etc.

Only done ones

New RBI Analysis results (Profast jnl files & database

New fatigue analysis

Fatigue Master Table




35

Relevant DNV Publications RP-F107 Pipeline Risk Assessment RP-G101 RBI of Topsides Equipment OS-E304 Offshore Mooring Steel Wire Ropes OSS-121 Class base on Risk Assessment OSS-303 Risk Based Verification OSS-304 Risk Based Verification of Offshore Structures

Available online: webshop.dnv.com




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DNV RP-F107 Pipeline Risk AssessmentCost Benefit Analysis Risk Matrix




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DNV RP-G101 RBI of Topsides Equipment

Maintenance Management System




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ISO 17776 (2000)




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Push-over Analysis




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SIM System




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Decision Time




43

To document safe use until end of production Date for change in platform operation(from manned to unmanned)

Cost and scheduling of structural mitigation

Objective Reassessment of Jacket Platforms:

Structural Operational Challenges

To document safe use until end of production Date for change in platform operation(from manned to unmanned)

Establish evacuation criteria Cost and scheduling of structural mitigation Inspection planning

Objective Reassessment of Jacket Platforms:

Wave diffraction Earthquake / Accidental Loads

COG

Structural modifications/ Weight Management

Subsidence of seabed/Possible WiD

Foundationcapacity

DeckStrength

Platform strength

New Env.Criteria

Fatigue strength &Inspection planning

Large amount of

information




44

Some Challenges

Wave-in-deck-load (WiD) and load on jacket (WoJ) and variation with time

-30

-20

-10

0

10

20

30

40

50

60

70

80

90

2.2 2.7 3.2 3.7 4.2 4.7 5.2 5.7 6.2 6.7 7.2 7.7 8.2 8.7 9.2 9.7

Time (sec)

F

x

(

M

N

)

-30

-20

-10

0

10

20

30

40

50

60

70

80

90

F

z

(

M

N

)

Fx - Total (inc. "jet" effect)Fx - WoJ (incl. "jet" effect)Fx - WoJ (without "jet" effect)Fx - WiD (Comflow)Fz - WoJ Fz - WiD (Comflow)




45

Challenges (contd)

Determination of failure criteria P

delta

Excessive deformation

P

Axial joint deformation, delta

Elasticflexibility

Dynamic behavior- Rise time for wave-in-deck load coincide with one quarter of platform

lowest eigenperiod




46

New vs. Old




47

NORSOK STANDARD N-006, March 2009




48

NORSOK Assessment Principles Requirements to in-service inspection planning and structural integrity management

of jacket structures in general may be found in ISO 19902, Clause 23.

Requirements to inspection and condition monitoring are given in ISO 19903, Chapter 14.

Requirements to in-service inspection, monitoring and maintenance are given in ISO 19904-1, Chapter 18.

Shut-down and unmanning procedure shall be implemented in order to ensure that there is less than 5x10-4 annual probability of the facility being exposed to environmental actions exceeding the structural capacity determined according to the ALS, with personnel onboard.

In cases of pollution risk or main safety function impairment it should be shown that the combined probability of a structural failure and leakage that could lead to significant pollution is less than 1x10-4 per year.




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API RP 2SIM (Draft) ToC




50

API RP 2SIM (Draft)

Data Evaluation Strategy Program

Managed systemfor archive andretrieval of SIMdata and other

pertinent records

Evaluation ofstructural integrity

and fitness forpurpose;

development ofremedial actions

Overall inspectionphilosophy &strategy andcriteria for in-

service inspection

Detailed workscopes forinspection

activities andoffshore execution

to obtain qualitydata

SIM Process and Document Organization

Data Evaluation Strategy ProgramInitiatorTriggered

Assessment

Yes

No

Source: Draft API RP 2SIM




51

API RP 2SIM (Draft) RBI Intervals

RiskCategory Inspection Interval Ranges

High 3-years to 5-years

Medium 6-years to 10-years

Low 11-years or greater

Notes:a) The timing for the first underwater periodic inspection should be determined

from the date of platform installation or when the baseline inspection was completed.

b) Risk-based intervals should be adjusted to verify uninterrupted cathodic protection of the platform. This should be based on data evaluation from prior inspections.

Assessment Initiator(See 4.3.5)

Assessment Category(See 4.3.4.4)

Assessment Information(See 7.3)

InadequateDeck Height?(see 4.3.5.1)

Simple Method(see 7.5)

Design Level Method

(see 7.6)

Ultimate Strength Method

(see 7.7)

Alternative Methods(see 7.8)

YES

Assessment MethodsSection 7

Assessment Criteria

- Design Level- Ultimate Strength- Environmental Load

Assessment CriteriaSections 8, 9

- Assessment Type- Assessment Category

- Assessment Criteria- Load Approach

RSR Criteria

- Assessment Category

- Minimum RSR

Pass Assessment? Mitigation and Risk Reduction Section 9

Document(see 4.2)

Consequence of Platform Failure (see 4.3.4)

MitigationAnd Risk

Assessment

AssessmentMethod

Assessment Category

and Assessment Information

Source: Draft API RP 2SIM




52

API 2A 20th and 21st Ed. RSRs

Assessment Category Reserve Strength Ratio (RSR)

A-1 High 1.21

A-2 Medium 0.8

A-3 Low 0.62

1. This RSR is applicable only for continued use of the platform for its present purpose. Not applicable for Change-of Use conditions.

2. Not to be used for water depth greater than 400 ft.


API RP2A 19th Edition and

Earlier

API RP2A 20th Edition and Later

A-1 High 1.6 2.0


GoM L-1 (High) 1.6 for Central Region11.2 for Other Regions

GoM L-2 (Medium) 1.2

GoM L-3 (Low) 1.0

Other U.S. Offshore Areas

2.0

1. Includes platforms located in the associated Transition Regions. The 100-year return period metocean conditions as defined in API RP2 MET should be used to compute the RSR.

20th Ed. GOM

20th Ed. Other U.S. Offshore Areas

21st Ed. GOM




53

Summary

Structural Integrity Management (SIM) and Risk based inspection planning (RBI) are tools employed to develop bases for asset management and in-service inspection in order to extend the useful life of the structure and increase its reliability level.

SIM is geared towards managing the asset data and communicating status to corporate management in a systematic manner.

RBI entails: - A risk screening process in order to identify critical areas and summarize the failure

modes. - The consequences of possible failures and repair strategy are established in close

co-operation with the operator. - The costs of inspection and repair for failures are established.- Probabilistic progressive collapse analyses are performed for a number of

representative mechanisms in the structures. - A cost optimal inspection strategy is established.

Finally, a user friendly tailor made software is developed to to perform the life cycle management of the Assets.




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Safeguarding life, property and the environment

www.dnv.com

Structural Integrity Management and Risk Based Inspection Recent DevelopmentsAgendaGOM Platform ActivityGOM Platform DecommissioningThe IssuesAPI RPs and GuidelinesAPI 2HINS Inspection Initiator ProcessDestroyed GoM Platforms Platform Structural AnalysisSafety format (LRFD vs. WSD) SIM ProcessPrinciples of Asset Integrity Management Integrity management life cycle activitiesWhy SIM - Ageing Problem?Ageing & Need for SIM & RBIWhat is Risk-Based Inspection (RBI)?Slide Number 16TerminologyThe Two Main Steps of RBIKey ConceptsSlide Number 20Reducing RiskMarine Safety RegulationsRisk AssessmentRisk AssessmentQuantitative MethodsInfluences on Technique SelectionTraditional Inspection Planning vs. RBI PlanningSuitable and Sufficient Inspection PlanningRBI Investment and Savingsrbi invesment & savingsORBIT StructureRBI Detailed Assessment RBI Detailed AssessmentInspection PlanningRelevant DNV PublicationsDNV RP-F107 Pipeline Risk AssessmentDNV RP-G101 RBI of Topsides EquipmentDNV RP-G101 RBI of Topsides EquipmentDNV RP-G101 RBI of Topsides EquipmentPush-over AnalysisSIM SystemDecision TimeSlide Number 43Some ChallengesChallenges (contd)New vs. OldNORSOK STANDARD N-006, March 2009NORSOK Assessment PrinciplesAPI RP 2SIM (Draft) ToCAPI RP 2SIM (Draft)API RP 2SIM (Draft) RBI IntervalsAPI 2A 20th and 21st Ed. RSRsSummarySlide Number 54

Structural Integrity Management and Risk Based Inspection – Recent Developments

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