1. Risk Based Inspection (RBI) - A Transparent Process?
Presented by: Cheryl Frolish
MACAW Engineering Ltd
Co-Authors: Ian Diggory, Richard Elsdon, Krista McGowan MACAW Engineering Ltd
Richard Jones Talisman Energy (UK) Limited 1

2. RBI & Operators Integrity Management Strategy RBI Concept & Schemes
Introduction
Topsides & Pipelines
RBI & Operators Integrity Management Strategy
RBI Concept & Schemes
Talisman RBI Process – MACAW Experience
Conclusions
Questions 2

3. Introduction Optimise Inspection Ensure Safe Operation
Why RBI?
Prioritise Inspection based on the Assessment of Risk
RBI Applications
Oil and Gas Industry
Topside Processes
Onshore Terminals
Pipeline Networks
Nuclear and Aviation Applications
Core Criteria
Optimise Inspection
Ensure Safe Operation
Provide an Audit Trail 3

4. Introduction 4 UK Regulations: Identify Hazards Prevent Detect Control
Mitigate
Reduce risk as low as reasonably practicable (ALARP)
HSE Guidance:
Best Practice for Risk Based Inspection as part of Plant Integrity Management
“Focuses on the form and management of RBI process rather than specific techniques or approaches” 4

5. Internal corrosion risks
Topsides & Pipelines
Topsides RBI and subsea risk assessments share many areas of commonality, in particular:
Internal corrosion risks
Topside Processing can be the CAUSE of corrosion issues in your pipeline:
For Example:
Water Carryover
Microbial Contamination
Condensation from Gas Phase
Process Upsets 5

6. Internal corrosion risks
Topsides & Pipelines
Topsides RBI and subsea risk assessments share many areas of commonality, in particular:
Internal corrosion risks
Topside Processing can be the SOLUTION to corrosion issues in your pipeline:
For Example:
Improved Separation Processes
Inhibitor Efficiency
Dew Point Control
Improve Process Reliability 6

7. Pipework and Vessel Inspections
Topsides & Pipelines
Knowledge of topside condition can give an early indication of potential pipeline integrity issues:
Pipework and Vessel Inspections
Condition
Other indications such as sand in the separators
Microbiological Surveys
Corrosion Coupons 7

8. Topsides and Pipelines - Example
Offshore Processing
Onshore Processing
Gas Pipeline
Oil Pipeline
Corrosion Coupon
Water Processing
Reservoir 8

9. Topsides and Pipelines - Example
The pipeline has just been re-inspected and a significant increase in corrosion activity has been noted. The pattern of corrosion is typical of water carryover into the pipeline (corrosion at the start of the line at the 6 o’clock position) caused by poor separation. Solution: increase residence time in the separators. BUT, why did the corrosion coupons not detect the corrosion….
Corrosion Coupon
Possible Causes:
Poor separation allowing for water carryover
Inhibitor partitioning time
Process Upsets
MIC 9

10. Topsides and Pipelines - Example
The corrosion coupons have not been showing any evidence of corrosion growth. WHY?
Gas Pipeline
Oil Pipeline
Position in the pipe
Location?
Ref for coupon pic: NACE Technical Committee Report. 1D199 Internal corrosion monitoring of subsea production and injection systems
Corrosion Coupon
Water Processing
Reservoir
RBI will identify HIGH risk areas. Interaction between topside and subsea assurance teams to determine location that best represents conditions in the pipeline. 10

11. RBI & Operators Integrity Management Strategy
Activities
Integrity Schemes
Corrosion Control Strategy
Monitoring and Mitigation
CRA, FFP & CGA (Pipeline)
RBI (Topsides)
Topside Inspection
Pipeline Inspection 11

12. RBI Concept 12

13. Internal Threats Internal Corrosion Sweet Corrosion
Sour Corrosion / Cracking Mechanisms
MIC (Microbiologically Induced Corrosion)
Oxygen Corrosion
Other potential mechanisms?
E.g. Acetic Acid weld degradation
Ref: MACAW Defect Atlas, Dr. Colin Argent 13

14. External Threats External Corrosion Atmospheric Corrosion
CUI (Corrosion Under Insulation)
Chloride pitting of stainless steels
Galvanic corrosion
Other potential mechanisms?
Ref: HSE Offshore External Corrosion Guide 14

15. Mitigation Internal External Linings Inhibitors Biocides
H2S Scavengers
O2 Scavengers
Gas dehydration – glycol towers and mol sieves
Dew Point Control
Material type
External
Coatings
Effective maintenance strategy (paint coatings and insulation cladding) 15

16. Consequences of Failure
Manning Levels
Fluid Type
Toxicity
Temperature and Pressure
Toxicity
Flammability
Safety
Environment
Location
Failure Mode
Size of Release
Flammability
Fluid Type
Temperature
Production
Commercial Criticality
Loss of Production
Back up systems? 16

17. RBI Concept 17

18. Inspection History IP 12 &13 Model Code of Safe Practice
API RP 570 & 510
Quantitative
Qualitative
Calculate time to failure based on wall thickness measurements.
Maximum inspection interval = ½ remaining service life
Effectiveness and results of inspections are graded. IP guidelines set out recommended maximum intervals based on inspection grade 18

19. Outcome of an RBI? Types of damage expected
Appropriate Inspection Technique
Inspection Frequency
Hotspot locations 19

20. RBI Schemes In 2002 HSE funded a study to compare several RBI schemes
Quantitative vs Qualitative
‘Black box’ approach
Varying levels of detail
HSE study identified the need for:
A TRANSPARENT process
A balance between quantitative and qualitative methods
A balance between theory, inspection and engineering judgement 20
Ref: Risk Based Inspection – A Case Study Evaluation of Onshore Process Plant, W Geary, 2002.

21. Talisman Assets North Sea Operator
11 Platforms
1 FPSO
2 Onshore Terminals
Network of over 3000 km of subsea pipelines
Ageing assets, near or past design life
Previous owners and inspection companies
Incomplete data set
Historical data often stored in hard copy only
Some existing RBI schemes but varied in type and complexity
A unified approach was required 21

22. A common feature of quantitative models
Talisman RBI Scheme
Initial Approach
Talisman had adopted an RBI program
Based on API half-remaining life approach
MACAW’s initial role to populate and run this program
Problem
Information was limited or just not available
Program required complete data set to operate successfully
A common feature of quantitative models
Gaps in inspection history and lack of confidence in results meant that API approach was not appropriate 22

23. MACAW and Talisman collaborated in development of a more robust scheme
Talisman RBI Scheme
MACAW and Talisman collaborated in development of a more robust scheme
MACAW applied the concept of ‘transparency’ to Talisman RBI scheme
Moved away from API approach to IP grading method
Top down approach, prioritised safety critical systems 23

24. Phase 1 - Safety Critical Systems Phases 2 & 3 – Less Critical Systems
Talisman Assets
Scale of the project:
11 platforms, 1 FPSO and 2 onshore terminals
Typical platform:
350 vessels (inc. heat exchangers, filters and air accumulators)
3000 items of pipework (grouped into ~120 streams)
For all of Talisman’s assets, this equates to approximately:
2500 Vessel RBIs
1700 Stream RBIs
The project was split into three phases
Phase 1 - Safety Critical Systems
Phases 2 & 3 – Less Critical Systems
Of 350 vessel approx 150 will be air accumulators. 24

25. RBI – The Key Steps MACAW Team Stakeholders Define Systems and Streams
Effective Communications
RBI – The Key Steps
MACAW Team
Stakeholders
Define Systems and Streams
Data Collection
Assess Corrosion Threats and Consequences
Assess Inspection History
Review Process
Documentation and Handover
Training and Technical Support
Implementing RBI
Updating RBI’s
Reviewing RBI’s
Define Scope
Transparent Decisions
Audit & Handover
Implementation
Live System 25

26. MACAW Team Project Manager (1) Senior Corrosion Engineers (2)
Project Supervisors (3)
Technical Assistants (6)
Team is set up to work on 6 RBI projects at a time
Data intensive process
Engineering assessment required on missing data
Organogram or list? 26

27. Stakeholders Talisman Inspection Company Assurance Engineer
Focal Point Engineer
Process Engineer
Chemist
Offshore Inspection Engineer
Inspection Company
Inspection Engineer
Corrosion Engineer 27

28. Systems and Streams
Systems are defined by their fluid and function, e.g.
Produced Oil & Oil Export
Gas Compression and Export
Fuel Gas
Systems determine equipment to be assessed, such as:
Separation vessels
Heat exchangers
Streams
Streams are used to define sections of pipework operating under similar parameters, such as:
Pressure
Temperature
Material
Fluid composition
Added chemicals (e.g. Corrosion Inhibitor injection) 28

29. Systems and Streams Process Flow Diagram extract Before stream mark upH I J K 29

30. Systems and Streams Process Flow Diagram extract After stream mark up12 30

31. Design and Operating Temperature Design and Operating Pressure
Data Collection
Fluid data
Design and operating details
Inspection history
Water Cut
Sand Content
CO2
H2S
Bug Count and Type pH O2
Corrosion Allowance
Design and Operating Temperature
Material
Design and Operating Pressure
Wall Thickness
Internal Lining
Inspection Type
Results and Conclusions 31

32. Assess Corrosion Threats and Consequences
Internal Corrosion Mechanisms
Susceptibility
Likelihood of Failure
Mitigation
External Corrosion Mechanisms
Susceptibility
Likelihood of Failure
Mitigation 32

33. Assess Inspection History
Inspection history and grading
IP 12 and 13 Inspection Grading method
Modified to incorporate risk
Example Pressure vessel inspections – next slide 33

34. Assess Inspection History
IP recommended maximum interval
Equipment
Grade 0
Grade 1
Grade 2
Grade 3
Process Pressure vessels and heat exchangers 36 48 84
144
RBI recommended maximum interval
Internal Inspection Intervals for Vessels and Heat Exchangers (Months)
Internal Risk
Grade 0
Grade 1
Grade 2
Grade 3
High 24 36 72 84
Medium 48
144
Low
NB: Hydrocarbon Systems will always fall into High and Medium Risk Categories due to the consequence of failure associated with these systems 34

35. Review Process Staged Review Process
Level 1: Peer Review of each system
Level 2: Integrity Review covering all systems within each phase
Representatives required from the following areas:
Assurance
Inspection
Process Engineering
Production Chemist
Operations
Site personnel
Safety and Environment 35

36. Documentation and Handover
Documentation of
Assumptions
Issues
Key decisions
Marked up PFD’s and P&ID’s
PFD’s hyperlinked to RBI’s
References for Data Sources
RBI’s in spreadsheet format
Change logging
Live summary sheet 36

37. Linked PFD and RBI Front Sheet37

38. Risk Assessment and Data Sources

39. Change Log and Prompts 39

40. Live Summary Sheet A B C D 40

41. Training and Technical Support
Helpdesk set up for ongoing technical support 41

42. Subsea Integrity Contractors Operating the Scheme
Once handed over the RBI becomes the responsibility of the client
Quality Controls
Allocated users
Permissions should be set up so that only persons who have attended training sessions may edit the RBI’s
Procedures for Updating and Reviewing Internally
Procedures for sharing RBI information with other interested parties
Subsea Integrity
Contractors 42

43. Conclusions Involve all stakeholders from the beginning of the process
Develop a system that can cope with variability of data
Decisions and criteria should be transparent
RBI is an ongoing process
The output from the RBI should carry through into pipeline integrity assessments 43

44. Thank you for your time, any questions?44