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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
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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
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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
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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
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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
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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
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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
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Topsides and Pipelines - Example
Offshore Processing Onshore Processing Gas Pipeline Oil Pipeline Corrosion Coupon Water Processing Reservoir 8
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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
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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
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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
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RBI Concept 12
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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
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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
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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
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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
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RBI Concept 17
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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
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Outcome of an RBI? Types of damage expected
Appropriate Inspection Technique Inspection Frequency Hotspot locations 19
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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.
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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
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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
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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
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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
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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
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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
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Stakeholders Talisman Inspection Company Assurance Engineer
Focal Point Engineer Process Engineer Chemist Offshore Inspection Engineer Inspection Company Inspection Engineer Corrosion Engineer 27
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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
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Systems and Streams Process Flow Diagram extract Before stream mark up
H I J K 29
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Systems and Streams Process Flow Diagram extract After stream mark up
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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
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Assess Corrosion Threats and Consequences
Internal Corrosion Mechanisms Susceptibility Likelihood of Failure Mitigation External Corrosion Mechanisms Susceptibility Likelihood of Failure Mitigation 32
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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
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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
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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
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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
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Linked PFD and RBI Front Sheet
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Risk Assessment and Data Sources
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Change Log and Prompts 39
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Live Summary Sheet A B C D 40
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Training and Technical Support
Helpdesk set up for ongoing technical support 41
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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
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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
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Thank you for your time, any questions?
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