The API 579 Fitness-for-Service Standard The Current State of Technology and a Ten Year Look Ahead

Robert Brown, P.E.

10th Annual IPEIA (formerly NPEC) Conference Banff Centre in Banff Alberta, Canada February 1 3, 2006

Presentation OutlineIntroductionAPI 579 Development BackgroundOverview of API 579New Joint API and ASME FFS StandardPlanned Developments for API/ASME 579Overview of API/ASME 579-2006Future Enhancements Following the 2006 Publication of API/ASME 579Technical Basis and Validation of API/ASME 579 FFS Assessment MethodsUnderstanding of Damage MechanismsIn-Service Inspection Codes and Fitness-For-ServiceFitness-For-Service and RBI - Complementary TechnologiesHarmonizing Pressure Vessel Design and Fitness-For-ServiceSummary

IntroductionThe ASME and API construction codes do not provide rules to evaluate a component containing a flaw or damage that results from operation after initial commissioningFitness-For-Service (FFS) assessments are quantitative engineering evaluations that are performed to demonstrate the structural integrity of an in-service component containing a flaw or damageAPI 579 was developed to evaluate flaws and damage associated with in-service operationAPI 579 assessment procedures were not originally intended to evaluate fabrication flaws; however, these procedures have been used for this purpose by many Owner-Users

IntroductionIf the damage mechanism cannot be identified, then a FFS assessment should not be performed per API 579Identification of damage mechanism is the key component in the FFS assessmentFirm understanding of the damage mechanism is required to evaluate the time-dependence of the damageTime-dependence of damage is required to develop a remaining life and inspection planAPI 579 provides guidance for conducting FFS assessments using methods specifically prepared for equipment in the refining and petrochemical industry; however, this document is currently being used in other industries such as the fossil utility, pulp & paper, food processing, and non-commercial nuclear

API 579 Development Background APIs Definition of Fitness-For-ServiceAn FFS assessment is a multi-disciplinary engineering analysis of equipment to determine whether it is fit for continued service, typically until the next shutdownThe equipment may contain flaws, not met current design standards, or be subjected to more severe operating conditions than current designThe product of a FFS assessment is a decision to run as is, monitor, alter, repair, or replace; guidance on an inspection interval is also providedFFS assessments consist of analytical methods (mainly stress analysis) to assess flaws and damage

API 579 Development Background Need for FFS Standardization Plant safety and Compliance with US OSHA 1910 Process Safety Management (PSM) LegislationOperation of aging facilitiesMaintaining safe, reliable operations with an increase in run-lengths, increase in severity of operations and/or decrease in shut-down periodsRationalizing flaws found by more rigorous in-service inspections than those conducted during original constructionRefining and petrochemical industry is unique due to the wide variety of processes and operating conditions, materials of construction, and damage mechanisms Standardization facilitates acceptance by jurisdictions

API 579 Development Background MPC FFS JIP Program OverviewJoint Industry Project (JIP) started in 1990 under The Materials Properties Council (MPC)Technology development focusBase resource document and computer software developedInformation disseminated to public through technical publications and symposiaTechnology developed provides basis for API 579Continued sponsorship by owner-users and funding support from API indicates high level of interest in FFSMPC FFS JIP continues to develop new FFS technology that is subsequently incorporated into API 579

Overview of API 579GeneralApplicable to pressurized components in pressure vessels, piping, and tankage (principles can also be applied to rotating equipment)Highly structured document with a modular organization based on flaw type/damage condition to facilitate use and updatesMulti-level assessment - higher levels are less conservative but require more detailed analysis/dataLevel 1 - Inspector/Plant EngineerLevel 2 - Plant EngineerLevel 3 - Expert Engineer

Overview of API 579 GeneralIdentifies data requirements, applicability and limitations of assessment procedures, and acceptance criteriaContains flow charts, figures, and example problems to simplify use of the assessment proceduresProvides recommendations for in-service monitoring and/or remediation for difficult situationsProvides recommendations for stress analysis techniques, NDE, and sources for materials propertiesRequires a remaining life to be evaluated; remaining life is the basis for the inspection interval

Overview of API 579 GeneralGeneral FFS assessment procedure used in API 579 for all flaw types is provided in Section 2 that includes the following steps:Step 1 - Flaw & damage mechanism identificationStep 2 - Applicability & limitations of FFS proceduresStep 3 - Data requirementsStep 4 - Assessment techniques & acceptance criteriaStep 5 - Remaining life evaluationStep 6 - RemediationStep 7 - In-service monitoringStep 8 - DocumentationSome of the steps shown above may not be necessary depending on the application and damage mechanism

Overview of API 579 ContentsAPI 579 originally released in 2000: Nine flaws and damage conditions are covered with supporting appendicesOrganized to facilitate use and updatesSection covering overall assessment procedureSeparate sections for each flaw type/conditionConsistent organization within each sectionInformation common to more than one section placed in appendicesSelf-contained document - do not need to purchase other API standards to perform an assessment

Overview of API 579 ContentsMain SectionsSection 1 - IntroductionSection 2 - FFS Engineering Evaluation ProcedureSection 3 - Assessment of Equipment for Brittle FractureSection 4 - Assessment of General Metal Loss (tm < tmin - large area)Section 5 - Assessment of Localized Metal Loss (tm < tmin - small area) Section 6 - Assessment of Pitting CorrosionSection 7 - Assessment of Blisters and LaminationsSection 8 - Assessment of Weld Misalignment and Shell DistortionsSection 9 - Assessment of Crack-Like FlawsSection 10 - Assessment of Equipment Operating in the Creep Regime (Draft version)Section 11 - Assessment of Fire Damage

Overview of API 579 ContentsAppendicesAppendix A - Thickness, MAWP, and Stress Equations for a FFS AssessmentAppendix B - Stress Analysis Overview for a FFS AssessmentAppendix C - Compendium of Stress Intensity Factor SolutionsAppendix D - Compendium of Reference Stress SolutionsAppendix E - Residual Stresses in a FFS EvaluationAppendix F - Material Properties for a FFS AssessmentAppendix G - Deterioration and Failure ModesAppendix H - ValidationAppendix I - Glossary of Terms and DefinitionsAppendix J - Technical Inquires

Overview of API 579 Relationships to Other FFS StandardsThe API Committee on Refinery Equipment (CRE) Task Group responsible for development of API 579 reviewed internal corporate methods, international standards and publications, and incorporated appropriate technologyIn most cases, modifications to existing or development of new FFS methods were requiredAPI Level 3 Assessments permit use of alternative FFS procedures. For example, Section 9 covering crack-like flaws provides reference to British Energy R-6, BS-7910, EPRI J-integral, and other published methodsThe API Task Group is working to set up technical liaisons with other international FFS standard writing bodies (e.g. FITNET)

New Joint API and ASME FFS StandardAPI and ASME have agreed to form a joint committee to produce a single FFS Standard that can be used for pressure-containing equipmentAPI 579 will form the basis of the new co-branded API/ASME standard that will be produced by this committeeThe initial release of the new co-branded standard designated as API/ASME 579 will occur in June, 2006

New Joint API and ASME FFS StandardThe second edition of API 579 and the new API/ASME joint standard will include all topics currently contained in API 579 and will also include new parts covering FFS assessment procedures that address unique damage mechanisms experienced by other industriesThe agreement to produce a joint standard on FFS technology is a landmark decision that will permit the focusing of resources in the US to develop a single document that can be used by all industriesIn addition, a joint FFS standard will help avoid jurisdictional conflicts and promote uniform acceptance of FFS technology

New Developments for API/ASME 579To avoid confusion with other ASME B&PV Codes and Standards, Sections in API 579 are being renamed to PartsNew Enhancements Existing Sections and New PartsPart 5 Assessment of Local Thin Areas, assessment procedures for gouges being relocated to Part 12Part 7 Assessment of Blisters and HIC/SOHIC Damage, assessment procedures for HIC/SOHIC damage have been addedPart 8 Assessment of Weld Misalignment and Bulges, assessment procedures for bulges being modified (in progress), assessment procedures for dents being relocated to Part 12Part 10 Assessment of Equipment Operating in the Creep Range, assessment procedures for remaining life calculations for components with or without crack-like flaws are providedPart 12 Assessment of Dents, Gouges, and Dent-Gouge Combinations, new PartPart 13 Assessment of Laminations, new Part

New Developments for API/ASME 579New Enhancements Existing and New AppendicesAppendix B Stress Analysis Overview for a FFS Assessment, complete rewrite to incorporate new elastic-plastic analysis methods and fatigue evaluation technology developed for the ASME Div 2 Re-write ProjectAppendix C Compendium of Stress Intensity Factor Solutions, new stress intensity factor solutions for thick wall cylinders, through wall cracks in cylinders and spheres, holes in platesAppendix E - Compendium of Residual Stress Solutions, complete rewrite to incorporate new solutions developed by PVRC Joint Industry ProjectAppendix F Material Properties for a FFS Assessment, new fracture toughness estimation methods and stress-strain curve model incorporatedAppendix H Technical Basis and Validation of FFS ProceduresAppendix K Crack Opening Areas, new appendix covering crack opening areas for through-wall flaws in cylinders and spheres

New Developments for API/ASME 579New Enhancements Example ProblemsAll example problems will be removed and placed in a separate example problems manualAdditional example problems with more background information will be providedFuture Enhancements (after 2006) - New PartsAssessment of Hot-SpotsAssessment of HTHA (High Temperature Hydrogen Attack) DamageAssessment of Fatigue Damage

Overview of API/ASME 579-2006Part 3: Brittle FractureProvides guidelines for evaluating the resistance to brittle fracture of existing carbon and low alloy steel pressure vessels, piping, and storage tanksScreening of equipment for susceptibility (Level 1 & 2)Detailed assessment using fracture mechanics (Level 3 per Part 9) Assessment typically performed on a weld-joint by weld joint basisThe purpose of this assessment is to avoid a catastrophic brittle fracture failure consistent with ASME Code, Section VIII design philosophy; however, it does not ensure against service-induced cracks resulting in leakage or arrest of a running brittle fracture

Overview of API/ASME 579-2006Part 3: Brittle Fracture - ChangesMinimal changes to existing API 579 methodology in Section 3; Changes in structure to improve user friendlinessMinimum Allowable Temperature (MAT) -Single temperature or envelope of temperature as function of pressureCritical Exposure Temperature (CET) -Lowest metal temperature at primary stress > 8 ksi

Overview of API/ASME 579-2006Part 4: General Metal LossCovers FFS for pressurized components subject to general metal loss resulting from corrosion and/or erosionProcedures can be applied to both uniform and local metal lossProcedures provide an MAWP or MATAssessment procedures in this section are based on a thickness averaging approachSuitable result is obtained when applied to uniform metal lossFor local or non-uniform metal loss, the Part 4 thickness averaging approach may produce overly conservative results; the assessment procedures of Part 5 (FFS rules covering local metal loss) can be utilized to reduce the conservatism in the analysis

Overview of API/ASME 579-2006Part 4: General Metal Loss - ChangesMinimal changes to existing API 579 methodology Change from tmin to trdNewExisting

trd

tmm

Overview of API/ASME 579-2006Part 5: Local Metal LossThe assessment procedures of Part 5 are for the analysis of local metal loss or Local Thin Areas (LTA)The procedures of Part 4 are for general (uniform and non-uniform) metal loss

Overview of API/ASME 579-2006Part 5: Local Metal Loss - ChangesLevel 1 AssessmentLongitudinal plane - screening curve changed to family of curves f(RSFa, E); groundwork for adapting to different CodesCircumferential plane - screening curve changed to family of curves f(RSFa, E); Includes 20% of allowable as bending stress; more conservativeLevel 2 AssessmentLongitudinal plane - New Folias factor; no limitation on length of LTA (was lambda

Overview of API/ASME 579-2006Part 5: Local Metal Loss - Changes New Level 2 Assessment procedure is provided for evaluating cylindrical shells with LTAs subject to external pressureNew method based on idealized cylindrical shellBasic equation is:

Overview of API/ASME 579-2006Part 6: PittingThe assessment procedures in Part 6 were developed to evaluate metal loss from pitting corrosionPitting is defined as localized regions of metal loss which can be characterized by a pit diameter on the order of the plate thickness or less, and a pit depth that is less than the plate thicknessAssessment procedures are provided to evaluate both widespread and localized pitting in a component with or without a region of metal lossThe procedures can be used to assess a damaged array of blisters as described in Part 7

Overview of API/ASME 579-2006Part 6: Pitting - ChangesLevel 1 ScreeningPitting ChartsVisual FFS Assessment (similar to ASME Code porosity charts),Current Level 1 and existing Level 2 merged into new Level 2Data for AssessmentInclude a photograph with reference scale and/or rubbing of the surfaceMaximum pit depthCross section of UT thickness scan can also be used

Overview of API/ASME 579-2006

Part 6: Pitting - ChangesPitting ChartsFFS by visually comparing pit chart to actual damage plus estimate of maximum pit depthPit charts provided for a different pitting damages measured as a percentage of the affected area in a 6 inch by 6 inchRSF provided for each pit density and four w/t ratios (0.2, 0.4, 0.6, 0.8)Pitting Chart API 579 Grade 4 Pitting

Overview of API/ASME 579-2006Part 6: Pitting - ChangesLevel 1 ScreeningDetermine ratio of remaining wall thickness to the future wall thickness in pitted region:Find pitting chart that matches damage and determine RSF

Overview of API/ASME 579-2006Part 7: Hydrogen Blisters and HIC/SOHIC (New)Provides assessment procedures for low strength ferritic steel pressurized components with hydrogen induced cracking (HIC) and blisters, and stress oriented HIC (SOHIC) damageExcludes:Sulfide stress cracking (SSC)Hydrogen embrittlement of high strength steels (Brinnell >232)Excludes methane blisteringHTHA

Overview of API/ASME 579-2006Part 7: Hydrogen Blisters and HIC/SOHIC (New)Various forms of damage all related to hydrogen being charged into the steel from a surface corrosion reaction in an aqueous H2S containing environment. Hydrogen BlisteringHydrogen blisters form bulges on the ID, the OD or within the wall thickness of a pipe or pressure vessel. Atomic H collects at a discontinuity (inclusion or lamination) in the steel H atoms form molecular hydrogen which is too large to diffuse out; pressure builds to excess of YS and local deformation occurs, forming a blisterHydrogen Induced Cracking (HIC)Hydrogen blisters can form at different depths from the surface. And may develop cracks that link them together. Interconnecting cracks between the blisters often are referred to as stepwise cracking

Overview of API/ASME 579-2006Part 7: Hydrogen Blisters and HIC/SOHIC (New)Stress Oriented Hydrogen Induced Cracking (SOHIC)Similar to HIC, but more damagingArrays of cracks stacked on top of each other, resulting in through-thickness crackSeen mostly in HAZ, due to residual stresses

Zero degree scan overlaid with 45 degree shearwave results (provided by Westech Inspection, Inc.)

Overview of API/ASME 579-2006Part 7: Hydrogen Blisters and HIC/SOHIC (New)Level 2 HIC AssessmentStrength check - Determine RSF by considering region as LTA with reduced strength (20%)Fracture check - Evaluate HIC as a crack-like flaw per Part 9

Overview of API/ASME 579-2006Part 8: Weld misalignment And Shell DistortionsThe procedures in this part can be used to assess weld misalignments and shell distortions in components made up of flat plates; cylindrical, conical, and spherical shells; and formed heads.Weld Misalignment centerline offset, angular misalignment (peaking), and a combination of centerline offset and angular misalignmentShell Distortion Categories include:General Shell DistortionOut-of-roundnessBulge

Overview of API/ASME 579-2006Part 8: Weld misalignment And Shell Distortions - ChangesPseudo code provided for computation of Fourier Series coefficients for analysis of out-of-roundness radius data Assessment procedure rules for bulges deleted, new rules currently being developed by MPC FFS JIP, will not be included in the 2006 edition

Overview of API/ASME 579-2006Part 9: Crack-Like FlawsCrack-like flaws are planar flaws which are predominantly characterized by a length and depth, with a sharp root radius, the types of crack-like flaws areSurface breakingEmbeddedThrough-wallIn some cases, it is conservative and advisable to treat volumetric flaws such as aligned porosity or inclusions, deep undercuts, root undercuts, and overlaps as planar flaws, particularly when such volumetric flaws may contain microcracks at the rootGrooves and gouges with a sharp root radius are evaluated using Section 9, criteria for the root radius is in Section 5

Overview of API/ASME 579-2006Part 9: Crack-Like Flaws The assessment procedures in Part 9 are based on a fracture mechanics approach considering the entire range of material behaviorBrittle fractureElastic/plastic fracturePlastic collapseInformation required to perform an assessment is provided in Part 9 and the following AppendicesAppendix C - Stress Intensity Factor SolutionsAppendix D - Reference Stress SolutionsAppendix E - Residual Stress SolutionsAppendix F - Material Properties

Overview of API/ASME 579-2006Part 9: Crack-Like Flaws - ChangesAppendix C - Stress Intensity Factor (K) Solutions Improved K solutions over larger range of geometries (Small R/t)K solutions for shallow cracks a/t

Overview of API/ASME 579-2006Part 10: Creep (New)API 579, Part 10 provides assessment procedures for pressurized components operating in the creep rangeThe temperature above which creep needs to be evaluated can be established using a Level 1 AssessmentAssessment procedures for determining a remaining life are provided for components with and without a crack-like flaw subject to steady state and/or cyclic operating conditionsThe procedures in this Part can be used to qualify a component for continued operation or for re-rating

Overview of API/ASME 579-2006Part 10: Creep (New)Level 1 Assessment - LimitationsComponent has been constructed to a recognized code or standardA history of the component can be provided covering both past and future operating conditions The component has been subject to less than 50 cycles of operation including startup and shutdown conditionsThe component does not contain a flaw such as an LTA, pitting or crack-like flawComponent has not been subject to fire damage or another overheating event that has resulted in a significant change in shape such as sagging or bulging, or excessive metal loss from scaling The material meets or exceeds minimum hardness and carbon content limitations

Overview of API/ASME 579-2006Part 10: Creep (New) Level 1 Assessment Calculations: single operating condition

Overview of API/ASME 579-2006Part 10: Creep (New) Level 1 Assessment Calculations: multiple operating condition

Overview of API/ASME 579-2006Part 10: Creep (New)Level 2 Assessment - LimitationsComponent has been constructed to a recognized code or standardA history of the component can be provided covering both past and future operating conditions The component has been subject to less than 50 cycles of operation including startup and shutdown conditionsThe component does not contain a flaw such as an LTA, pitting or crack-like flawLevel 2 Assessment - CalculationsAnalysis (i.e. FEA) used to determine temperature and stress as a function of timeMaterial data and damage rule used to determine acceptability for continued operationMethod based on MPC Project Omega JIP

Overview of API/ASME 579-2006Part 11: Fire DamageCovers assessment procedures for evaluating pressure vessels, piping and tanks subjected to flame impingement and the radiant heat of a fireAssessment procedures address the visually observable structural degradation of components and the less apparent degradation of mechanical properties, such as strength, ductility, and toughness Assessment procedures may also be used to evaluate process upsets due to a chemical reaction within process vesselsPart 11: Fire Damage - ChangesReference provided to new Part 10 to evaluate creep damage resulting from a fire

Overview of API/ASME 579-2006Part 12: Dents, Gouges, and Dent-Gouge Combinations (New)Assessment procedures for pressurized components containing dents, gouges, or dent-gouge combinations resulting from mechanical damage Dent An inward or outward deviation of a cross-section of a shell member from an ideal shell geometry that is characterized by a small local radius or notchGouge An elongated local removal and/or relocation of material from the surface of a component caused by mechanical means that results in a reduction in wall thickness; the material may have been cold worked in the formation of the flaw Dent-Gouge Combination A dent with a gouge present in the deformed region

Overview of API/ASME 579-2006Part 12: Dents, Gouges, and Dent-Gouge Combinations (New)Assessment procedures permit calculation of MAWP or MFHLevel 1 Assessment Procedures based on simple screening criteriaLevel 2 Assessment Procedures require some stress analysis, fatigue calculation method included for dent and dent-gouge combinations

Overview of API/ASME 579-2006Part 13: Laminations (New)Covers assessment procedures for pressurized components with laminations, excluding HIC or SOHIC damage Laminations are defined as a plane of non-fusion in the interior of a steel plate that results during the steel manufacturing processExisting assessment procedures in Part 7 will be significantly updated

Overview of API/ASME 579-2006Appendices updates previously discussed have been completedAppendix B Stress Analysis Overview for a FFS Assessment - Change, complete rewrite to incorporate new elastic-plastic analysis methods and fatigue evaluation technology developed for the ASME Div 2 Re-write ProjectAppendix C Compendium of Stress Intensity Factor Solutions - Change, new stress intensity factor solutions for thick wall cylinders, through wall cracks in cylinders and spheres, holes in platesAppendix E - Compendium of Residual Stress Solutions - Change, complete rewrite to incorporate new solutions developed by PVRC Joint Industry ProjectAppendix F Material Properties for a FFS Assessment - Change, new fracture toughness estimation methods and stress-strain curve model incorporatedAppendix H Technical Basis and Validation of FFS Procedures NEW, technical basis document that provides an overview of the technical background and validation with essential referencesAppendix K Crack Opening Areas - NEW, appendix covering crack opening areas for through-wall flaws in cylinders and spheres

Future Enhancements After the 2006 Publication of API/ASME 579Technology Development Efforts Currently UnderwayDocumentation of validation of new assessment procedures for HIC/SOHIC damage (2006)Allowable Remaining Strength Factor (RSFa) calibration based on original construction code (2006)Assessment of local thin areas (2007)Development of a new method for computing the RSF factor for both Level 1 and Level 2 AssessmentsDevelopment of new LTA-to-LTA spacing criteriaDevelopment of new LTA-to-structural discontinuities spacing criteria Development of new rules for assessment of local thin areas at nozzles and other shell discontinuitiesCompletion of Example Problems Manual (2007)

Future Enhancements After the 2006 Publication of API/ASME 579Technology Development Efforts Currently UnderwayAssessment Procedures for bulges (2007)Assessment of crack-like flaws (2007)New PSF (Partial Safety Factors) for crack-like flaws, introduction of PSFs for LTAsDevelopment of new reference stress solutions based on J-Integral TechniqueEvaluation of weld mismatch effectsAssessment procedures for HTHA (2007)Assessment procedures for hot-spots (2008)Assessment of damage in cast iron components (paper mill dryers) (2008)

Future Enhancements After the 2006 Publication of API/ASME 579Future Technology NeedsImproved fracture toughness evaluation for in-service materialsCarbon steel and low alloysEnvironmental effects (e.g. hydrogen)Temperature dependencyStatistical evaluationImproved assessment procedures for dents and dent-gouge combinationsRemoval of geometry restrictionsCoverage of more materialsCoverage of more loading typesEvaluation of material toughness effects on the burst pressure of components with non-crack-like flaws (i.e. LTAs, pitting)

Future Enhancements After the 2006 Publication of API/ASME 579Future Technology NeedsAssessment Procedures for Crack-Like FlawsFAD dependency on stress-strain curveEvaluation of pressure test and warm pre-stress effectsImproved crack growth models, including data, considering environmental effortsAssessment Procedures for FatigueMultiaxial fatigueCycle countingEnvironmental effectsAssessment Procedures for Creep DamageInclude primary creep in MPC Project Omega Creep ModelCreep damage from triaxial stress statesDevelopment of new procedures to evaluate creep-fatigue damageNew procedures to evaluate creep-buckling

Future Enhancements After the 2006 Publication of API/ASME 579Future Technology NeedsImproved Stress-Strain ModelsTemperature EffectsLoading Rate EffectsCyclic Stress-Strain CurvesIntroduction of partial safety factors for other types of damage (i.e. LTA, pitting)Additional stress intensity factor solutions for common pressurized component geometries (e.g. cracks at nozzles)

Technical Basis and Validation of API/ASME 579 FFS Assessment MethodsThe API CRE FFS and Joint API/ASME Committees are committed to publishing the technical basis to all FFS assessment procedures utilized in API 579 in the public domainIt is hoped that other FFS standards writing committees adopt the same policy as it is crucial that FFS knowledge remains at the forefront of technology on an international basis to facilitate adoption by jurisdictional authoritiesThe new API 579 Appendix H of API 579 provides an overview of technical basis and validation with related references organized by damage type, the references are published in a series of WRC Bulletins and technical papers

Technical Basis and Validation of API/ASME 579 FFS Assessment MethodsWRC Bulletins PublishedReview of Existing Fitness-For-Service Criteria for Crack-Like Flaws (WRC 430)Technologies for the Evaluation of Non-Crack-Like Flaws in Pressurized Components - Erosion/Corrosion, Pitting, Blisters, Shell Out-of-Roundness, Weld Misalignment, Bulges, and Dents in Pressurized Components (WRC 465)Development of Stress Intensity Factor Solutions for Surface and Embedded Cracks in API 579 (WRC 471)Stress Intensity and Crack Growth Opening Area Solutions for Through-wall Cracks in Cylinders and Spheres (WRC 478)Recent Progress in Analysis of Welding Residual Stresses (WRC 455)Recommendations for Determining Residual Stresses in Fitness-For-Service Assessments (WRC 476)Master S-N Curve Method for Fatigue Evaluation of Welded Components (WRC 474)

Technical Basis and Validation of API/ASME 579 FFS Assessment MethodsWRC Bulletins PendingCompendium of Temperature-Dependent Physical Properties for Pressure Vessel Materials (WRC 503) An Overview and Validation of The Fitness-For-Service Assessment Procedures for Locally Thin Areas in API 579 (WRC 505)

Technical Basis and Validation of API/ASME 579 FFS Assessment MethodsWRC Bulletins In PreparationAn Overview of The Fitness-For-Service Assessment Procedures for Pitting Damage in API 579An Overview of the Fitness-For-Service Assessment Procedures for Weld Misalignment and Shell Distortions in API 579An Overview and Validation of the Fitness-For-Service Assessment Procedures for Crack-Like Flaws in API 579 An Overview and Validation of Residual Stress Distributions for Use in the Assessment Procedures of Crack-Like Flaws in API 579 An Overview and validation of the Fitness-For-Service Rules for the Assessment of HIC/SOHIC Damage in API 579

Technical Basis and Validation of API/ASME 579 FFS Assessment MethodsWRC Bulletins In PreparationMPC Project Omega and Procedures for Assessment of Creep Damage in API 579Development of a Local Strain Criteria Based on the MPC Universal Stress-Strain EquationUpdate on the Master S-N Curve Method for Fatigue Evaluation of Welded Components

Understanding of Damage MechanismsThe first step in a Fitness-For-Service assessment performed in accordance with API 579 is to identify the flaw type and associated damage mechanismAppendix G in API 579 provides basic information to assist the practitioner in this stepThe following WRC Bulletins have been produced to provide the practitioner with in-depth informationDamage Mechanisms Affecting Fixed Equipment in the Pulp and Paper Industry (WRC 488)Damage Mechanisms Affecting Fixed Equipment in the Refining Industry (WRC 489 & API RP 571)Damage Mechanisms Affecting Fixed Equipment in the Fossil Electric Power Industry (WRC 490)

In-Service Inspection Codesand Fitness-For-ServiceJurisdictional acceptance provided by reference from in-service inspection codes in the USAPI 510 VesselsAPI 570 PipingAPI 653 TankageANSI/NB-23 Vessels & BoilersStatus of reference from US inspection codes is as follows:API 510 Reference in 8th Edition, 2nd AddendumAPI 570 Reference in 2nd Edition, 2nd AddendumAPI 653 Reference to appear in 3rd Edition, 1st AddendumANSI/NB-23 Reference in Introduction of 2001 AddendumWorking to achieve recognition by other international in-service inspections codes

In-Service Inspection Codesand Fitness-For-ServiceReactive FFS can be used to assess damage found during an inspection; provides basis for run, repair, or replace decisionProactive FFS can be used prior to shut-downs to help develop inspection plans (e.g. determine maximum permissible flaws sizes)The remaining life is determined as part of an FFS assessment:Used to establish an inspection intervalHalf-life or similar concepts can be usedSnap-Shot approach to FFS is not adequate, an evaluation of the time dependency of damage is required

Fitness-For-Service and RBI - Complimentary TechnologiesAssessment of damage in many of the RBI methods currently being used is needs updating; is not consistent with FFS assessment proceduresDocumented and validated FFS methods for flaw and damage assessment may be used to establish a probability of failure as a function of time by considering uncertainties in the damage model and independent variablesThe resulting probably of failure can be combined with a consequence model to produce an estimate of risk as a function of timeTime dependency of risk permits development of an inspection planWork is underway to integrate API 579 with API 581

Harmonizing Pressure Vessel Design and Fitness-For-ServiceTo remain technically competitive, and to facilitate incorporation of new technology and future updates, ASME is developing a new pressure Vessel Code; this code will replace the existing Section VIII, Division 2 CodeThe new code is being developed primarily to address design and fabrication of engineered pressure vessels (as typically used in the refining and petrochemical industry); will result in significant cost savingsThe new code is consistent with developments in Europe Objective to develop a new organization and introduce a clear and consistent writing style to facilitate use; consistent with API-579 philosophyShared technology between API-579 and new design Code. Draft version of new Code is complete; work is underway to ballot the Div 2 Rewrite in 2006

SummaryFitness-For-Service (FFS) assessments are quantitative engineering evaluations that are performed to demonstrate the structural integrity of an in-service component containing a flaw or damageAPI and ASME have agreed to form a joint committee to produce a single FFS Standard, API/ASME 579, that can be used for pressure-containing equipmentPermits focusing of resources in the US to develop a single document that can be used by all industriesHelps avoid jurisdictional conflicts and promotes uniform acceptance of FFS technologyThe 2006 edition of API/ASME 579 represents a significant update in assessment proceduresThe technical basis and validation of the API/ASME 579 FFS assessment procedures will be published in the public domainAPI/ASME 579 FFS assessment methods have been integrated with API & NBIC inspection codes and will be integrated into API RBI technologiesSignificant technical development work remains and a work plan is being formulated

Robert Brown, P.E.FFS Team Leader216-283-6015rgbrown@equityeng.com

20600 Chagrin Blvd. Suite 1200Shaker Heights, OH 44122 USAPhone: 216-283-9519 Fax: 216-283-6022www.equityeng.com

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