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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]