RBI for Offshore Pipelines – Challenges in Theory and ... - Subsea UK

RBI for Offshore Pipelines – Challenges in Theory and
Practice
Dr. Gundula Stadie-Frohbös / Dr. Felix Weise
www.futureship.net

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. 2

GL is global service provider in maritime and energy
market (oil & gas, renewables)
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
6,800 Employees in 80 Countries
GL offices
Employees
Americas
1.050
Europe
3.300
Africa
100
Strong growth accelerated by acquisitions
[EURm]
Middle
East
550
Asia
1.450
Australia,
Pacific
350
800
Renewables (GL Garrad Hassan)
Certification
Engineering Consulting
Marine Operations
Measurements
Software Products
Training
184
Industrial 35
Maritime 149
2000
205
43
162
2001
208
43
165
2002
222
50
172
2003
270
56
214
2004
327
72
255
2005
370
89
281
2006
429
128
301
2007
567
231
336
2008
430
370
2009E
RBI for Offshore Pipelines – Challenges in Theory and Practice | 2011-12-01 | No. 3

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

Reasons for leakage
Nat. Hazard
0%
Material - steel
defect
8%
Material - weld
defects
6%
Structural
0%
Other
14%
Corrosion
38%
Anchor
16%
Impact
18%
RBI for Offshore Pipelines – Challenges in Theory and Practice | 2011-12-01 | No. 5

Introduction: What is risk?
Risk - understanding
What goes
wrong?
How often?
What are the
consequences?
Scenario
(e.g. fire, oil spill,
collision, etc.)
Probability
(e.g. 1 in 1000 years,
1 in 100 years, etc.)
Measure of damages
(e.g. €1M damage,
3 injuries, etc.)
Risk = probability of failure x consequence of failure
RBI for Offshore Pipelines – Challenges in Theory and Practice | 2011-12-01 | No. 6

Risk management - covering life cycle of the asset
Conceptual design
Detailed design
Construction
Commissioning
Operation & Maintenance
Life time extension
Decommissioning
RBI for Offshore Pipelines – Challenges in Theory and Practice | 2011-12-01 | No. 7

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

GALIOM for Pipelines
Risk = PoF ×
Design Index
Corrosion Index
CoF
Probability
of failure
PoF Index
Third Party Index
Operation Index
Probability of
failure (PoF) can
often be estimated!
Main technical
aspects are
considered within
GALIOM.
Operation
Pressure
Location
Class
Contents
type
Economical
consequence
Human safety
Consequence
of failure
Spill volume
Consequence of a
failure (CoF) shall
be assessed
carefully!
Risk is the
combination of
PoF and CoF
Environmental
impact
Reputation
and political
consequence
RBI for Offshore Pipelines – Challenges in Theory and Practice | 2011-12-01 | No. 9

Probability of failure | Two track concept
Semi - quantitative approach
Index procedure leads to
an overview of the current
status of the pipeline
Probability of Failure
Remaining life time
is directly related to
time dependent effects
Corrosion
Design
Remaining Life Time
Design...
Operation
Index Procedure
Third Party
Crossing
Fatigue
Pressure
Corrosion
...
RBI for Offshore Pipelines – Challenges in Theory and Practice | 2011-12-01 | No. 10
Free Span
PoF obtained by worst case result of both assessment methods

Risk matrix & Inspection intervals
Results used to
generate inspection
strategy which
considers cost
and safety aspects.
increasing
decreasing
RBI for Offshore Pipelines – Challenges in Theory and Practice | 2011-12-01 | No. 11
Fixed inspection intervals (e.g. by
owner or authority requirements)
can be considered as well
according to experience of
measurements.

Case Study – Two flaws, same flaw geometry and
different consequences
Production Platform
Probability of Failure
Flaw A
Consequence
Flaw B
Risk development for two
equivalent corrosion flaws,
with same corrosion growth,
however, different consequence
levels
Consequence
Negligible
Low
Medium
High
Serious
B
Negligible
A
Low
Medium
B
A
High
B
A
Serious
B
A
Pipeline with different consequence areas
a/t
1
0.8
0.6
0.4
0.2
2008
2004
2000
2012
0
0 0.2 0.4 0.6 0.8 1
c/D
Flaw assessment according to RSTRENG
Flaw B
Flaw A
RBI for Offshore Pipelines – Challenges in Theory and Practice | 2011-12-01 | No. 12

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

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. 14

Evaluation of design index
100
80
60
40
20
0
More precise information
about the influences of
different topics on the
individual phases of the
“life cycle”, here: “Design”
with respect to failure
probability.
Pressure
Manufacturing
Global checks
Local checks
Soil
On-bottom Stability
Free Span
Fatigue
RBI for Offshore Pipelines – Challenges in Theory and Practice | 2011-12-01 | No. 15

Assessment of remaining life time - example
Remaining life time [years]
80.00
70.00
60.00
50.00
40.00
30.00
20.00
10.00
0.00
Fatigue Corrosion Design
Overview of current life time considering different influence factors
RBI for Offshore Pipelines – Challenges in Theory and Practice | 2011-12-01 | No. 16

Displaying risk in GALIOM
Risk
Risk displayed in a
5 x 5 risk matrix
What Facility, Group or
Equipment has the Highest Risk
Cons
eque
nce
Negligi
ble
Low
Failure Probability
Mediu
m
High
Serious
Negli
gible
Low
Medi
um
1
High
2
Serio
us
Risk for different pipeline segement
RBI for Offshore Pipelines – Challenges in Theory and Practice | 2011-12-01 | No. 17

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. 18

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

Thanks for your attention!
Contact details:
Dr. Gundula Stadie-Frohbös
Tel. : 0049 40 36149 991
Email: gsf@gl-group.com
www.futureship.net