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RBI Methodology

RBI Methodology. Risk Based Inspection. API 580 – 581. Introduction.

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RBI Methodology

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  1. RBI Methodology Risk Based Inspection API 580 – 581 Donegani Anticorrosione S.r.l

  2. Introduction Although the term ‘RBI’ has been adopted relatively recently, the practice of planning plant inspection based on the risk of failure is not new. Most operators base the scope and depth of their inspection plans on the rate of in-service damage and the consequence of failure, within a traditional time-based inspection programme. (Same operators can rightly claim that their plant inspections have always been risk-based). The term ‘RBI’ refers to a structured, team-based assessment process with the aim of targeting inspection by considering the Risk of Failure (RoF), which is a combination of the Likelihood of Failure (LoF) and Consequence of Failure (CoF). Donegani Anticorrosione S.r.l

  3. RBI – Risk Based Inspection • Is based on the norms API 581 & RP 580 • Developed by API (American Petroleum Institute) in collaboration with: - DOW - SHELL - FINA - TEXACO - EXXON - …………. Donegani Anticorrosione S.r.l

  4. Objective of RBI Methodology • Increase safety • Increase the productivity of inspection • Decrease the losses of production • Reduce the direct costs of inspection • Change the frequencies of inspections in base to the risk • Prevent catastrophic damages Donegani Anticorrosione S.r.l

  5. RISK Definition of the Risk: Risk (RoF) = Likelihood of Failure (LoF) x Consequence of Failure (CoF) Donegani Anticorrosione S.r.l

  6. Risk Based Inspection Consent of: • Define the critical state for every single ITEM • Create a priority for the Inspections basing on the critical state • Focus the attention on the expected damages Donegani Anticorrosione S.r.l

  7. RBI Methodology RBI Methodology developed by different companies, varied in the details, but it is founded however on fundamental step: • Background to RBI • Assessment Personnel • Damage Mechanism Assessment • Risk Assessment • Inspection Planning and Risk Mitigation • Updating RBI Assessment Donegani Anticorrosione S.r.l

  8. Step 1. Background to RBI Step 2. Assessment Personnel Step 3. Damage Mechanism Assessment Step 4.1. Likelihood of failure-LoF Step 4.2. Consequence of failure-CoF Step 4.3 Risk Assessment Step 5. Inspection Planning Step 6. Updating RBI Assessment RBI Methodology Donegani Anticorrosione S.r.l

  9. Background to RBI RBI study is designed around the systematic, inductive assessment process of identifying historical, active or potential damage mechanism in each equipment. The process is a ‘bottom up’ procedure where one damage mechanism id considered at a time. Once the feasible damage mechanisms have been identified, their probabilities (likelihood) of leading to component failure are determined and their effects on the components are recorder and analysed to yield a calculated failure consequence. Donegani Anticorrosione S.r.l

  10. Assessment Personnel All RBI systems have the following common elements: • Assessment preparation • Information Gathering • Damage Mechanism Review • Risk Assessment • Inspection Plans • Inspection Review. Donegani Anticorrosione S.r.l

  11. Assessment preparation Since RBI is a team-based approach, the first step in the introduction of an RBI programme is to identify and assemble a competent Study Team. The RBI team should include staff with knowledge of plant operation, process hazards, risk assessment and inspection techniques. Donegani Anticorrosione S.r.l

  12. Typical RBI team • Inspection engineer(s); • Material and corrosion engineer(s); • Maintenance engineer(s); • Process engineer(s); • Operations engineer(s); • Safety engineer(s); • Team leader, typically a RBI specialist(s). Donegani Anticorrosione S.r.l

  13. Information Gathering Are necessary the following information: • Operational manual • P&ID • Sketches of project of the equipment • Pipe class • Property of the fluids • Design and operating conditions • Special instructions and History inspection • …………… Donegani Anticorrosione S.r.l

  14. Damage Mechanism Assessment The Study Team will need to review the historical and generic date relevant to each item of equipment. This will include consideration of previous inspection reports (if available) to determine the known or expected damage mechanisms. The review should consider damage mechanisms which may lead to failure, their expected rates of deterioration and the general location where damage may arise. Wherever quantitative rates of damage are not available, an element of expert judgement will need to be exercised by the Study Team. Donegani Anticorrosione S.r.l

  15. Risk Assessment The failure likelihood and the failure consequence are calculated on the basis of quantitative Likelihood Factors (LF) and Consequence Factors (CF). Donegani Anticorrosione S.r.l

  16. Likelihood of Failure (LoF) The answers to the LF questions are assigned a series of values and associated weighting and the combination of all these determines the Likelihood of Failure (LoF), derived for each equipment in turn. The LoF formula is specifically of the following form: LoF = LF2 Σ (LFi) LF2 = Failure likelihood (within a given period of time) LFi = represents several factors that are considered to contribute to the overall Likelihood of Failure. Donegani Anticorrosione S.r.l

  17. LFi Factors • LF1: Current condition • LF2: Failure likelihood • LF3: Inspection Effectiveness • LF4: Shutdown Frequency • LF5: Operational Stability • LF6: Operation in Relation to Design • LF7: Recurring Repairs Donegani Anticorrosione S.r.l

  18. Consequence of Failure (CoF) The answers to the Consequence Factors (CF) questions are assigned a series of values and associated weightings and the combination of these results is the Consequence of Failure (CoF), derived for each item in turn. The CoF formula is specifically of the following form: CoF = (FM x CF1 x CF2) + (CF3 x CF6) + CF4 + (CF5 x CF7) + CF8 + CF9 Donegani Anticorrosione S.r.l

  19. FM Factor In addition to other consequence factors the consequence calculation also consider the failure mode of an assigned damage mechanism. Each damage mechanism knowledge base is assigned one of three failure modes, i.e. ‘Leakage’, ‘Leakage or Rupture’, ‘Rupture’. Donegani Anticorrosione S.r.l

  20. CFi Factors • CF1: Product Loss • CF2: Pressure Factor • CF3: Explosion/Fire Damage Potential • CF4: Toxicity • CF5: Effect of Failure on Production • CF6: Location of Component • CF7: Time Taken to Rectify Failure • CF8: Threat Personnel/Environment • CF9: Engineered Safety Systems Donegani Anticorrosione S.r.l

  21. Weight of Factors Donegani Anticorrosione S.r.l

  22. Risk Matrix The resultant Likelihood of Failure (LoF) is plotted on the vertical axis, and the Consequence of Failure (CoF) is plotted on the horizontal axis, as an assessment point on a dimensionless five-by-five Risk Plot. The Lof axis is grouped into five relative Likelihood Categories, ranging from 1 to 5 (approximately 10-2/yr to 10-7/yr), and the CoF axis is grouped into five relative Consequence Categories, ranging from A to E. In this way, the Risk of Failure (RoF) is considered to increase with increasing LoF and CoF. Donegani Anticorrosione S.r.l

  23. Risk Matrix 5 4 Risk Likelihood 3 2 1 A B C D E Consequence Donegani Anticorrosione S.r.l

  24. Inspection Planning After the risk assessment, the Study Team develops action plan based on all of expected damage mechanisms. The inspection plane consider the inspection interval and the scope of inspection. The proposed inspection plane are designed to provide an assurance that the ‘residual risk’ of the equipment is in accordance with the ‘ALARP’ principle, i.e. the aim of assessing and managing equipment is to reduce the RoF to As Low As is Reasonably Practicable (‘ALARP’). Donegani Anticorrosione S.r.l

  25. Risk Mitigation The RBI methodology systematically leads the Study Team through the process of risk mitigation, by considering several mitigation action. The impact of each mitigation action can be evaluated, for subsequent collective appraisal of the benefits of the proposed action, using the ALARP principle. An appropriate strategy to manage the integrity of each equipment is therefore developed. Donegani Anticorrosione S.r.l

  26. Updating RBI Assessment RBI Study can be used to justify extending the periods between inspections. The RBI process relies on a feedback loop to update the inspection plan, such that it is relevant to the actual condition of the plan. The feedback stage provides continuing confidence that damage dose not exceed expectations and ensures that plan inspections take account of operational experience. Once an inspection plan has been developed during a session, future inspection of the equipment should be carried out to confirm that damage rates are within expectations and to identify any unexpected damage. The inspection should be carried out by competent staff and the results recorded and re-evaluated. Donegani Anticorrosione S.r.l

  27. FeedBack of the Study Plant Operation Plant Operation Shutdown/ Inspection Inspection Plan Rev.0 Inspection Reporting Inspection Plan Rev.1 Start RBI Maintenance Shutdown Base RBI Assessments Review RBI Assessments Maintenance Shutdown Donegani Anticorrosione S.r.l

  28. Risk vs TimeNo Inspection Plan 180 months 120 months 60 months Donegani Anticorrosione S.r.l

  29. Risk vs Time With Inspection Plan 180 months 120 months 60 months Donegani Anticorrosione S.r.l

  30. DONEGANI ANTICORROSIONE SRL VIA G. FAUSER 36/A 28100 NOVARA Tel. 0321677411 Fax. 0321677444 E-mail: segreteria@donegant.it Web: www.donegant.it Donegani Anticorrosione S.r.l

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