Technical Standards and Legislation: Risk Based Inspection Presenter: Pierre Swart
Agenda Change in Legislation. Where RBI fits in. Application to implement RBI. RBI concepts. Elements of an RBI analysis. Keeping RBI evergreen.
Change in Legislation With change from VUP regulation to PER in 2009, RBI is mandatory for vessels in corrosive service where inspection intervals above 36 months are required.
Pressure Equipment Regulation Pressure Equipment Regulation PRESCRIPTIVE =<36 months SELF REGULATING >36 months RBI QA MANUAL DEFINING RBI SCHEME. Management System AUDIT/APPROVE RBI SCHEME- Certification Body approved by SANAS
Application to implement RBI Formal application to DOL which includes: Copy of RBI management system. Name of chief RBI specialist and qualifications. RBI team competency and qualifications. Technical standard to be used. Name of Certification Body. Name of AIA. Letter of recommendation from AIA to implement RBI.
Basic Concepts What is RBI? Risk-Based Inspection (API 580) Method using RISK as a basis for prioritising and managing of inspection programs 1 2 3 3 2 4 3 2 5 4 3 3 2 Consequence 1 High 1 Medium Low
Basic Concepts Risk Based Approach Inspection program based on risk level. High risk items inspected more frequently and more stringently. Utilise the most appropriate inspection technique for the detection of identified degradation mechanisms. Understanding what degradation can occur, the most suitable inspection technique can be selected. Consider the likelihood of degradation mechanisms. Inspect only for the degradation mechanisms that have a probability of occurring.
Basic Concepts Material Loss of Containment (Consequence) Contents Degradation Mechanism (Probability/Likelihood) Environment
Basic Concepts What to consider if starting with RBI Deciding on the RBI approach will have a significant impact on resources and information required. Qualitative: less rigorous but also less resources and information. Semi-quantitative: Dependent on level of quantification. Benefit of less data and resources than quantitative but more data and resources than qualitative. Quantitative: Most data and resources required. Should only require this approach in specific cases.
Elements of an RBI analysis Data Collection for RBI Assessment Depends on level of assessment (Qualitative, Semi-quantitative and quantitative). Material of construction, insulation, cladding and design parameters such as pressures, temperatures. Operating parameters such as pressure, temperature and process fluid composition and properties. Population density, distance from water, towns. Mitigation measures such as bunds, shut off valves, fire brigade.
Elements of an RBI analysis Data Collection for RBI Assessment Data quality will influence accuracy of analysis. Sources of data. Code data book. Process flow diagram Mechanical flow diagram Inspection records
Elements of an RBI analysis Determine Consequences of Failure Loss of Containment The consequence is determined as the effect of the fluid loss to the environment. Factors taken into account can be type of fluid, state of fluid, properties of fluid, process variables, mass of fluid, failure mode leak size.
Elements of an RBI analysis Determine Consequences of Failure Categories of consequence effects for loss of containment Safety and health impact (explosion; flash fire; pool fire; toxicity; pressure wave) Environmental impact. (liquid spills; vapour releases; ground water contamination) Business losses due to production loss and maintenance and reconstruction costs Units of measure Quantitative analysis: expressed as numeric value. Qualitative analysis expressed as category, e.g high, medium, low or 1 through 5.
Elements of an RBI analysis Determine Probability of Failure Probability of all deterioration mechanisms must be determined. Thinning: loss of material through corrosion and erosion Cracks: Stress Corrosion Cracking, Sulfide Stress Cracking, Hydrogen Induced Cracking Metallurgical and environmental: High Temperature Hydrogen Attack, Embrittlement, Metal Dusting. Mechanical: Mechanical Fatigue, Brittle Fracture.
Elements of an RBI analysis Determine Probability of Failure Units of measure in the probability of failure analysis Quantitative analysis: expressed as frequency, e.g. fixed interval (one per year, one in ten years) or as events per interval (0.0002 failures per year) Qualitative analysis uses categorisation, e.g high, medium, low or 1 through 5. Determine Probability Of Failure (POF) Identify active and credible deterioration mechanisms. Determine deterioration susceptibility and rate. Quantify effectiveness of inspection and maintenance program Determine probability that with current condition, predicted deterioration will result in failure
Elements of an RBI analysis Risk determination, Assessment and Management Determining risk Risk = Probability X Consequence Quantitative risk = sum of individual risks for each specific consequence, where individual risks or risk of specific consequence = (probability of specific consequence) X (specific consequence). Qualitative risk = (overall probability rating) X (overall consequence rating)
Elements of an RBI analysis Risk determination, Assessment and Management Risk management decisions and acceptable levels of risk. Acceptable levels of risk determined by company. Use of RBI results to determine inspection programme. Risk Presentation. Risk plot or Risk Matrix to help visualise the results of the study.
Elements of an RBI analysis Risk management with inspection activities Managing risk by reducing uncertainty through inspection Where risk is driven by probability of failure, there is potential for risk management through inspection. Use of RBI results to determine what to inspect, how to inspect (technique), and extent of inspection (coverage). Therefore RBI results forms an input to the Equipment Maintenance Strategy (FMEA) of the equipment. In the FMEA specify mitigating actions to be taken if secondary action trigger requirements are met.
Elements of an RBI analysis Other risk mitigation activities. Where inspection activities may not be sufficient, other mitigation activities could include: Equipment repair, replacement or upgrade, Change in operating conditions, Equipment redesign. Therefore the outputs of an RBI session can be integrated with other business processes such as the life cycle management process for updating of renewal plans, and the Integrity Operating Window process to manage production parameters.
Elements of an RBI analysis Re-assessment and updating RBI assessments. RBI is a dynamic tool and should be updated when changes to the equipment or process occur or when new information becomes available as a result of inspection activities. Most damage mechanisms are time dependant and therefore the risk profile of the equipment will change over time.
Keeping RBI evergreen RBI meeting RBI recommendations FMEA CMMS Execution of Inspections Inspection Report External triggers Legislation changes, new settlements close to plant, etc. Internal triggers Request for Delay, changes to equipment design or operating parameters, loss of containment incidents, etc.
References Documents Health and safety standards for RBI as listed in SANS 347 Appendix A: API Recommended Practice 580: Risk-Based Inspection. ASME PCC-3-2007: Inspection Planning Using Risk Based Methods. CWA 15740: Risk-Based Inspection and Maintenance Procedures for European Industry (RIMAP)