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

1. The API 579 Fitness-for-Service Standard – The Current State of Technology and a Ten Year Look Ahead 10th Annual IPEIA (formerly NPEC) Conference Banff Centre in Banff Alberta, Canada February 1 – 3, 2006 Robert Brown, P.E.

2. Presentation Outline • Introduction • API 579 Development Background • Overview of API 579 • New Joint API and ASME FFS Standard • Planned Developments for API/ASME 579 • Overview of API/ASME 579-2006 • Future Enhancements Following the 2006 Publication of API/ASME 579 • Technical Basis and Validation of API/ASME 579 FFS Assessment Methods • Understanding of Damage Mechanisms • In-Service Inspection Codes and Fitness-For-Service • Fitness-For-Service and RBI - Complementary Technologies • Harmonizing Pressure Vessel Design and Fitness-For-Service • Summary

3. Introduction • The ASME and API construction codes do not provide rules to evaluate a component containing a flaw or damage that results from operation after initial commissioning • Fitness-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 damage • API 579 was developed to evaluate flaws and damage associated with in-service operation • API 579 assessment procedures were not originally intended to evaluate fabrication flaws; however, these procedures have been used for this purpose by many Owner-Users

4. Introduction • If the damage mechanism cannot be identified, then a FFS assessment should not be performed per API 579 • Identification of damage mechanism is the key component in the FFS assessment • Firm understanding of the damage mechanism is required to evaluate the time-dependence of the damage • Time-dependence of damage is required to develop a remaining life and inspection plan • API 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

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

6. API 579 Development BackgroundNeed for FFS Standardization • Plant safety and Compliance with US OSHA 1910 Process Safety Management (PSM) Legislation • Operation of aging facilities • Maintaining safe, reliable operations with an increase in run-lengths, increase in severity of operations and/or decrease in shut-down periods • Rationalizing flaws found by more rigorous in-service inspections than those conducted during original construction • Refining 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

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

8. Overview of API 579General • Applicable 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 updates • Multi-level assessment - higher levels are less conservative but require more detailed analysis/data • Level 1 - Inspector/Plant Engineer • Level 2 - Plant Engineer • Level 3 - Expert Engineer

9. Overview of API 579 General • Identifies data requirements, applicability and limitations of assessment procedures, and acceptance criteria • Contains flow charts, figures, and example problems to simplify use of the assessment procedures • Provides recommendations for in-service monitoring and/or remediation for difficult situations • Provides recommendations for stress analysis techniques, NDE, and sources for materials properties • Requires a remaining life to be evaluated; remaining life is the basis for the inspection interval

10. Overview of API 579 General • General 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 identification • Step 2 - Applicability & limitations of FFS procedures • Step 3 - Data requirements • Step 4 - Assessment techniques & acceptance criteria • Step 5 - Remaining life evaluation • Step 6 - Remediation • Step 7 - In-service monitoring • Step 8 - Documentation • Some of the steps shown above may not be necessary depending on the application and damage mechanism

11. Overview of API 579 Contents • API 579 originally released in 2000: Nine flaws and damage conditions are covered with supporting appendices • Organized to facilitate use and updates • Section covering overall assessment procedure • Separate sections for each flaw type/condition • Consistent organization within each section • Information common to more than one section placed in appendices • Self-contained document - do not need to purchase other API standards to perform an assessment

12. Overview of API 579Contents Main Sections • Section 1 - Introduction • Section 2 - FFS Engineering Evaluation Procedure • Section 3 - Assessment of Equipment for Brittle Fracture • Section 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 Corrosion • Section 7 - Assessment of Blisters and Laminations • Section 8 - Assessment of Weld Misalignment and Shell Distortions • Section 9 - Assessment of Crack-Like Flaws • Section 10 - Assessment of Equipment Operating in the Creep Regime (Draft version) • Section 11 - Assessment of Fire Damage

13. Overview of API 579 Contents Appendices • Appendix A - Thickness, MAWP, and Stress Equations for a FFS Assessment • Appendix B - Stress Analysis Overview for a FFS Assessment • Appendix C - Compendium of Stress Intensity Factor Solutions • Appendix D - Compendium of Reference Stress Solutions • Appendix E - Residual Stresses in a FFS Evaluation • Appendix F - Material Properties for a FFS Assessment • Appendix G - Deterioration and Failure Modes • Appendix H - Validation • Appendix I - Glossary of Terms and Definitions • Appendix J - Technical Inquires

14. Overview of API 579 Relationships to Other FFS Standards • The 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 technology • In most cases, modifications to existing or development of new FFS methods were required • API 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 methods • The API Task Group is working to set up technical liaisons with other international FFS standard writing bodies (e.g. FITNET)

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

16. New Joint API and ASME FFS Standard • The 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 industries • The 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 industries • In addition, a joint FFS standard will help avoid jurisdictional conflicts and promote uniform acceptance of FFS technology

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

18. New Developments for API/ASME 579 • New Enhancements – Existing and New Appendices • Appendix 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 Project • Appendix 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 plates • Appendix E - Compendium of Residual Stress Solutions, complete rewrite to incorporate new solutions developed by PVRC Joint Industry Project • Appendix F – Material Properties for a FFS Assessment, new fracture toughness estimation methods and stress-strain curve model incorporated • Appendix H – Technical Basis and Validation of FFS Procedures • Appendix K – Crack Opening Areas, new appendix covering crack opening areas for through-wall flaws in cylinders and spheres

19. New Developments for API/ASME 579 • New Enhancements – Example Problems • All example problems will be removed and placed in a separate example problems manual • Additional example problems with more background information will be provided • Future Enhancements (after 2006) - New Parts • Assessment of Hot-Spots • Assessment of HTHA (High Temperature Hydrogen Attack) Damage • Assessment of Fatigue Damage

20. Overview of API/ASME 579-2006 • Part 3: Brittle Fracture • Provides guidelines for evaluating the resistance to brittle fracture of existing carbon and low alloy steel pressure vessels, piping, and storage tanks • Screening 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 basis • The 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

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

22. Overview of API/ASME 579-2006 • Part 4: General Metal Loss • Covers FFS for pressurized components subject to general metal loss resulting from corrosion and/or erosion • Procedures can be applied to both uniform and local metal loss • Procedures provide an MAWP or MAT • Assessment procedures in this section are based on a thickness averaging approach • Suitable result is obtained when applied to uniform metal loss • For 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

23. Overview of API/ASME 579-2006 • Part 4: General Metal Loss - Changes • Minimal changes to existing API 579 methodology • Change from tmin to trd Existing New

24. Overview of API/ASME 579-2006 • Part 5: Local Metal Loss • The 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

25. Overview of API/ASME 579-2006 • Part 5: Local Metal Loss - Changes • Level 1 Assessment • Longitudinal plane - screening curve changed to family of curves f(RSFa, E); groundwork for adapting to different Codes • Circumferential plane - screening curve changed to family of curves f(RSFa, E); Includes 20% of allowable as bending stress; more conservative • Level 2 Assessment • Longitudinal plane - New Folias factor; no limitation on length of LTA (was lambda<5) • Circumferential plane - Added “circumferential” Folias factor to analysis; changed acceptability criteria from yield basis to allowable stress basis

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

27. Overview of API/ASME 579-2006 • Part 6: Pitting • The assessment procedures in Part 6 were developed to evaluate metal loss from pitting corrosion • Pitting 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 thickness • Assessment procedures are provided to evaluate both widespread and localized pitting in a component with or without a region of metal loss • The procedures can be used to assess a damaged array of blisters as described in Part 7

28. Overview of API/ASME 579-2006 • Part 6: Pitting - Changes • Level 1 Screening • Pitting Charts • Visual FFS Assessment (similar to ASME Code porosity charts), • Current Level 1 and existing Level 2 merged into new Level 2 • Data for Assessment • Include a photograph with reference scale and/or rubbing of the surface • Maximum pit depth • Cross section of UT thickness scan can also be used

29. Overview of API/ASME 579-2006 • Part 6: Pitting - Changes • Pitting Charts • FFS by visually comparing pit chart to actual damage plus estimate of maximum pit depth • Pit charts provided for a different pitting damages measured as a percentage of the affected area in a 6 inch by 6 inch • RSF 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

30. Overview of API/ASME 579-2006 • Part 6: Pitting - Changes • Level 1 Screening • Determine ratio of remaining wall thickness to the future wall thickness in pitted region: • Find pitting chart that matches damage and determine RSF

31. Overview of API/ASME 579-2006 • Part 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) damage • Excludes: • Sulfide stress cracking (SSC) • Hydrogen embrittlement of high strength steels (Brinnell >232) • Excludes methane blistering • HTHA

32. Overview of API/ASME 579-2006 • Part 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 Blistering • Hydrogen 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 blister • Hydrogen 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”

33. Overview of API/ASME 579-2006 • Part 7: Hydrogen Blisters and HIC/SOHIC (New) • Stress Oriented Hydrogen Induced Cracking (SOHIC) • Similar to HIC, but more damaging • Arrays of cracks stacked on top of each other, resulting in through-thickness crack • Seen mostly in HAZ, due to residual stresses Zero degree scan overlaid with 45 degree shearwave results (provided by Westech Inspection, Inc.)

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

35. Overview of API/ASME 579-2006 • Part 8: Weld misalignment And Shell Distortions • The 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 misalignment • Shell Distortion – Categories include: • General Shell Distortion • Out-of-roundness • Bulge

36. Overview of API/ASME 579-2006 • Part 8: Weld misalignment And Shell Distortions - Changes • Pseudo 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

37. Overview of API/ASME 579-2006 • Part 9: Crack-Like Flaws • Crack-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 are • Surface breaking • Embedded • Through-wall • In 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 root • Grooves and gouges with a sharp root radius are evaluated using Section 9, criteria for the root radius is in Section 5

38. Overview of API/ASME 579-2006 • Part 9: Crack-Like Flaws • The assessment procedures in Part 9 are based on a fracture mechanics approach considering the entire range of material behavior • Brittle fracture • Elastic/plastic fracture • Plastic collapse • Information required to perform an assessment is provided in Part 9 and the following Appendices • Appendix C - Stress Intensity Factor Solutions • Appendix D - Reference Stress Solutions • Appendix E - Residual Stress Solutions • Appendix F - Material Properties

39. Overview of API/ASME 579-2006 • Part 9: Crack-Like Flaws - Changes • Appendix C - Stress Intensity Factor (K) Solutions • Improved K solutions over larger range of geometries (Small R/t) • K solutions for shallow cracks a/t<0.2 improved • Appendix E – New Residual Stress Solutions based on PVRC Residual Stress JIP research • Appendix F - Material Properties, new methods to estimate fracture toughness based on MPC FFS JIP research co-funded by API

40. Overview of API/ASME 579-2006 • Part 10: Creep (New) • API 579, Part 10 provides assessment procedures for pressurized components operating in the creep range • The temperature above which creep needs to be evaluated can be established using a Level 1 Assessment • Assessment 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 conditions • The procedures in this Part can be used to qualify a component for continued operation or for re-rating

41. Overview of API/ASME 579-2006 • Part 10: Creep (New) • Level 1 Assessment - Limitations • Component has been constructed to a recognized code or standard • A 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 conditions • The component does not contain a flaw such as an LTA, pitting or crack-like flaw • Component 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

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

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

44. Overview of API/ASME 579-2006 • Part 10: Creep (New) • Level 2 Assessment - Limitations • Component has been constructed to a recognized code or standard • A 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 conditions • The component does not contain a flaw such as an LTA, pitting or crack-like flaw • Level 2 Assessment - Calculations • Analysis (i.e. FEA) used to determine temperature and stress as a function of time • Material data and damage rule used to determine acceptability for continued operation • Method based on MPC Project Omega JIP

45. Overview of API/ASME 579-2006 • Part 11: Fire Damage • Covers assessment procedures for evaluating pressure vessels, piping and tanks subjected to flame impingement and the radiant heat of a fire • Assessment 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 vessels • Part 11: Fire Damage - Changes • Reference provided to new Part 10 to evaluate creep damage resulting from a fire

46. Overview of API/ASME 579-2006 • Part 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 notch • Gouge – 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

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

48. Overview of API/ASME 579-2006 • Part 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 process • Existing assessment procedures in Part 7 will be significantly updated

49. Overview of API/ASME 579-2006 • Appendices – updates previously discussed have been completed • Appendix 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 Project • Appendix 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 plates • Appendix E - Compendium of Residual Stress Solutions - Change, complete rewrite to incorporate new solutions developed by PVRC Joint Industry Project • Appendix F – Material Properties for a FFS Assessment - Change, new fracture toughness estimation methods and stress-strain curve model incorporated • Appendix H – Technical Basis and Validation of FFS Procedures – NEW, technical basis document that provides an overview of the technical background and validation with essential references • Appendix K – Crack Opening Areas - NEW, appendix covering crack opening areas for through-wall flaws in cylinders and spheres

50. Future Enhancements After the 2006 Publication of API/ASME 579 • Technology Development Efforts Currently Underway • Documentation 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 Assessments • Development of new LTA-to-LTA spacing criteria • Development of new LTA-to-structural discontinuities spacing criteria • Development of new rules for assessment of local thin areas at nozzles and other shell discontinuities • Completion of Example Problems Manual (2007)