RBI for Offshore Pipelines – Challenges in Theory and · PDF file RBI for Offshore Pipelines – Challenges in Theory and Practice Dr. Gundula Stadie-Frohbös / Dr. Felix Weise

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RBI for Offshore Pipelines – Challenges in Theory and PracticeDr. Gundula Stadie-Frohbös / Dr. Felix Weise

RBI for Offshore Pipelines – Challenges in Theory and Practice | 2011-12-01 | No. 2

RBI for Offshore Pipelines – Challenges in Theory and Practice

•Short Presentation of GL

• Introduction / Basics

•Risk based method

•Example: Offshore pipeline

RBI for Offshore Pipelines – Challenges in Theory and Practice | 2011-12-01 | No. 3

Employees

GL offices350

Australia,Pacific

1.450

Asia

550

MiddleEast

100

Africa1.050

Americas

3.300

Europe

6,800 Employees in 80 Countries

Strong growth accelerated by acquisitions

[EURm]

Maritime

� Classification of 6,800 ships in service

� Plan approval and new build supervision

of 500 ships p.a.

� Maritime Systems & Components

� Maritime Solutions

Oil & Gas (GL Noble Denton)

� Technical Assurance

� Engineering Consulting

� Asset Performance & Maintenance

� Marine Operations & Consulting

� Project Execution

� Software Products

Renewables (GL Garrad Hassan)

� Certification

� Engineering Consulting

� Marine Operations

� Measurements

� Software Products

� Training

GL is global service provider in maritime and energy market (oil & gas, renewables)

89

149

184

2000

43

162

205

2001

43

165

208

2002

50

172

222

2003

214

270

2004

7256

327

2005

28135255

370

2006

128

301

429

2007

231

336

567

2008

430

370

800

2009E

Industrial

Maritime

RBI for Offshore Pipelines – Challenges in Theory and Practice | 2011-12-01 | No. 4

Introduction / Basics

RBI for Offshore Pipelines – Challenges in Theory and Practice | 2011-12-01 | No. 5

Reasons for leakage

Anchor

16%

Impact

18%

Corrosion38%

Structural

0%

Material - weld

defects

6%

Material - steel

defect

8%

Nat. Hazard

0%

Other

14%

RBI for Offshore Pipelines – Challenges in Theory and Practice | 2011-12-01 | No. 6

Introduction: What is risk?

Risk = probability of failure x consequence of failure

Risk - understandingRisk Risk -- understandingunderstanding

How often?How often?What goes wrong?

What goes wrong?

What are the consequences?

What are the consequences?

Scenario(e.g. fire, oil spill,

collision, etc.)

Measure of damages(e.g. €1M damage,

3 injuries, etc.)

Probability(e.g. 1 in 1000 years,1 in 100 years, etc.)

RBI for Offshore Pipelines – Challenges in Theory and Practice | 2011-12-01 | No. 7

Risk management - covering life cycle of the asset

Conceptual design

Detailed design

Commissioning

Operation & Maintenance

Life time extension

Decommissioning

Construction

RBI for Offshore Pipelines – Challenges in Theory and Practice | 2011-12-01 | No. 8

Risk method – Example

RBI for Offshore Pipelines – Challenges in Theory and Practice | 2011-12-01 | No. 9

Risk = PoF × CoF

Probability of failure

PoFIndex

Corrosion Index Operation Index

Third Party Index

Probability of failure

PoFIndex

Corrosion Index Operation Index

Third Party IndexDesign Index

Environmental impact

Reputation

and politicalconsequence

Human safety

Economicalconsequence

Consequenceof failure

Environmental impact

Reputation

and politicalconsequence

Human safety

Economicalconsequence

Consequenceof failureLocation

Class

Operation

Pressure

Spill volumeContents

type

Location

Class

Operation

Pressure

Spill volumeContents

type

GALIOM for Pipelines

Probability of

failure (PoF) can

often be estimated!

Main technical

aspects are

considered within

GALIOM.

Consequence of a

failure (CoF) shall

be assessed

carefully!

Risk is the

combination of

PoF and CoF

RBI for Offshore Pipelines – Challenges in Theory and Practice | 2011-12-01 | No. 10

Probability of failure | Two track conceptSemi - quantitative approach

Index Procedure

Remaining Life Time

Probability of Failure

DesignDesign

Corrosion

Fatigue

Operation Third PartyPressure

Free Span

Crossing

...

...

Corrosion

PoF obtained by worst case result of both assessment methods

Index procedure leads to

an overview of the current

status of the pipeline

Remaining life time

is directly related to

time dependent effects

RBI for Offshore Pipelines – Challenges in Theory and Practice | 2011-12-01 | No. 11

Risk matrix & Inspection intervals

increasing decreasingResults used to

generate inspection

strategy which

considers cost

and safety aspects.

Fixed inspection intervals (e.g. by

owner or authority requirements)

can be considered as well

according to experience of

measurements.

RBI for Offshore Pipelines – Challenges in Theory and Practice | 2011-12-01 | No. 12

Consequence

Production Platform

Consequence

Production Platform

0

0.2

0.4

0.6

0.8

1

0 0.2 0.4 0.6 0.8 1

c/D

a/t

Case Study – Two flaws, same flaw geometry and different consequences

Serious

High

Medium

Low

Negligible

Serious

High

Medium

Low

Negligible

Probability of Failure

Conse-

quence

Serious

High

Medium

Low

Negligible

Serious

High

Medium

Low

Negligible

Probability of Failure

Conse-

quence

Flaw A

Flaw B

B

A

20042000

2008

2012

B

AAA

B B

Flaw A

Flaw B

Flaw assessment according to RSTRENG

Pipeline with different consequence areas

Risk development for two

equivalent corrosion flaws,

with same corrosion growth,

however, different consequence

levels

RBI for Offshore Pipelines – Challenges in Theory and Practice | 2011-12-01 | No. 13

Example: Pipeline

RBI for Offshore Pipelines – Challenges in Theory and Practice | 2011-12-01 | No. 14

Pipeline

Outer diameter Wall thickness Operating pressure Medium Age

32 in 30 mm 200 bar Crude oil 29 Jahre

Changing risk

RBI for Offshore Pipelines – Challenges in Theory and Practice | 2011-12-01 | No. 15

Evaluation of design index

0

20

40

60

80

100

Press

ure

Man

ufac

turin

g

Global

chec

ks

Loca

l che

cks

SoilO

n-bo

ttom

Sta

bility

Free

Span

Fatig

ue

More precise information

about the influences of

different topics on the

individual phases of the

“life cycle”, here: “Design”

with respect to failure

probability.

RBI for Offshore Pipelines – Challenges in Theory and Practice | 2011-12-01 | No. 16

0.00

10.00

20.00

30.00

40.00

50.00

60.00

70.00

80.00

Fatigue Corrosion Design

Rem

aining life tim

e [yea

rs]

Assessment of remaining life time - example

Overview of current life time considering different influence factors

RBI for Offshore Pipelines – Challenges in Theory and Practice | 2011-12-01 | No. 17

Displaying risk in GALIOM

Risk displayed in a

5 x 5 risk matrix

Serio

us

2High

1Medi

um

Low

Negligible

SeriousHighMediu

m

LowNegligi

ble

Failure ProbabilityConseque

nce

Risk for different pipeline segement

Risk

What Facility, Group or

Equipment has the Highest Risk

RBI for Offshore Pipelines – Challenges in Theory and Practice | 2011-12-01 | No. 18

Conclusions

• Support for evaluation of global pipeline integrity

• Shows unknown topics, e.g. missing soil analysis

• Ranking

• Focus on areas with higher failure probability (condition based maintenance) and

higher consequences (risk based maintenance / inspection)

RBI for Offshore Pipelines – Challenges in Theory and Practice | 2011-12-01 | No. 19

What are the Advantages of Performing RBI

• Distinct knowledge of Deterioration Modes and Mechanisms that are affecting

equipment

Look Less – More Focus

• Reduction in Shutdown Inspections in favour of On-Stream Methodologies

Shorter Shutdowns – Greater Availability

• Develop Run to Failure methodologies for Low Consequence Equipment

Reduced Maintenance – Cost Saving

• Reduction in Unforeseen Repairs

Greater Availability

• Ability to identify Risk Mitigation Measures to reduce either the Consequence of

Failure or Probability of Failure

Improved Safety

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Thanks for your attention!

Contact details:

Dr. Gundula Stadie-Frohbös

Tel. : 0049 40 36149 991

Email: [email protected]