The API 579 Fitness-for-Service Standard

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 APIs 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 Background Need 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 579 Contents

• 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
  lt tmin - large area)
• Section 5 - Assessment of Localized Metal Loss
  (tm lt 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 BPV 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 gt 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 lambdalt5)
• 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 gt232)
• 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/tlt0.2 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)

51
Future Enhancements After the 2006 Publication of
API/ASME 579

• Technology Development Efforts Currently Underway
• Assessment Procedures for bulges (2007)
• Assessment of crack-like flaws (2007)
• New PSF (Partial Safety Factors) for crack-like
  flaws, introduction of PSFs for LTAs
• Development of new reference stress solutions
  based on J-Integral Technique
• Evaluation of weld mismatch effects
• Assessment procedures for HTHA (2007)
• Assessment procedures for hot-spots (2008)
• Assessment of damage in cast iron components
  (paper mill dryers) (2008)

52
Future Enhancements After the 2006 Publication of
API/ASME 579

• Future Technology Needs
• Improved fracture toughness evaluation for
  in-service materials
• Carbon steel and low alloys
• Environmental effects (e.g. hydrogen)
• Temperature dependency
• Statistical evaluation
• Improved assessment procedures for dents and
  dent-gouge combinations
• Removal of geometry restrictions
• Coverage of more materials
• Coverage of more loading types
• Evaluation of material toughness effects on the
  burst pressure of components with non-crack-like
  flaws (i.e. LTAs, pitting)

53
Future Enhancements After the 2006 Publication of
API/ASME 579

• Future Technology Needs
• Assessment Procedures for Crack-Like Flaws
• FAD dependency on stress-strain curve
• Evaluation of pressure test and warm pre-stress
  effects
• Improved crack growth models, including data,
  considering environmental efforts
• Assessment Procedures for Fatigue
• Multiaxial fatigue
• Cycle counting
• Environmental effects
• Assessment Procedures for Creep Damage
• Include primary creep in MPC Project Omega Creep
  Model
• Creep damage from triaxial stress states
• Development of new procedures to evaluate
  creep-fatigue damage
• New procedures to evaluate creep-buckling

54
Future Enhancements After the 2006 Publication of
API/ASME 579

• Future Technology Needs
• Improved Stress-Strain Models
• Temperature Effects
• Loading Rate Effects
• Cyclic Stress-Strain Curves
• Introduction 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)

55
Technical Basis and Validation of API/ASME 579
FFS Assessment Methods

• The 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 domain
• It 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 authorities
• The 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

56
Technical Basis and Validation of API/ASME 579
FFS Assessment Methods

• WRC Bulletins Published
• Review 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)

57
Technical Basis and Validation of API/ASME 579
FFS Assessment Methods

• WRC Bulletins Pending
• Compendium 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)

58
Technical Basis and Validation of API/ASME 579
FFS Assessment Methods

• WRC Bulletins In Preparation
• An Overview of The Fitness-For-Service Assessment
  Procedures for Pitting Damage in API 579
• An Overview of the Fitness-For-Service Assessment
  Procedures for Weld Misalignment and Shell
  Distortions in API 579
• An 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

59
Technical Basis and Validation of API/ASME 579
FFS Assessment Methods

• WRC Bulletins In Preparation
• MPC Project Omega and Procedures for Assessment
  of Creep Damage in API 579
• Development of a Local Strain Criteria Based on
  the MPC Universal Stress-Strain Equation
• Update on the Master S-N Curve Method for Fatigue
  Evaluation of Welded Components

60
Understanding of Damage Mechanisms

• The first step in a Fitness-For-Service
  assessment performed in accordance with API 579
  is to identify the flaw type and associated
  damage mechanism
• Appendix G in API 579 provides basic information
  to assist the practitioner in this step
• The following WRC Bulletins have been produced to
  provide the practitioner with in-depth
  information
• Damage 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)

61
In-Service Inspection Codesand
Fitness-For-Service

• Jurisdictional acceptance provided by reference
  from in-service inspection codes in the US
• API 510 Vessels
• API 570 Piping
• API 653 Tankage
• ANSI/NB-23 Vessels Boilers
• Status of reference from US inspection codes is
  as follows
• API 510 Reference in 8th Edition, 2nd Addendum
• API 570 Reference in 2nd Edition, 2nd Addendum
• API 653 Reference to appear in 3rd Edition, 1st
  Addendum
• ANSI/NB-23 Reference in Introduction of 2001
  Addendum
• Working to achieve recognition by other
  international in-service inspections codes

62
In-Service Inspection Codesand
Fitness-For-Service

• Reactive FFS can be used to assess damage found
  during an inspection provides basis for run,
  repair, or replace decision
• Proactive 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 interval
• Half-life or similar concepts can be used
• Snap-Shot approach to FFS is not adequate, an
  evaluation of the time dependency of damage is
  required

63
Fitness-For-Service and RBI - Complimentary
Technologies

• Assessment of damage in many of the RBI methods
  currently being used is needs updating is not
  consistent with FFS assessment procedures
• Documented 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 variables
• The resulting probably of failure can be combined
  with a consequence model to produce an estimate
  of risk as a function of time
• Time dependency of risk permits development of an
  inspection plan
• Work is underway to integrate API 579 with API 581

64
Harmonizing Pressure Vessel Design and
Fitness-For-Service

• To 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 Code
• The 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 savings
• The 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
  philosophy
• Shared 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

65
Summary

• 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 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 equipment
• Permits focusing of resources in the US to
  develop a single document that can be used by all
  industries
• Helps avoid jurisdictional conflicts and promotes
  uniform acceptance of FFS technology
• The 2006 edition of API/ASME 579 represents a
  significant update in assessment procedures
• The technical basis and validation of the
  API/ASME 579 FFS assessment procedures will be
  published in the public domain
• API/ASME 579 FFS assessment methods have been
  integrated with API NBIC inspection codes and
  will be integrated into API RBI technologies
• Significant technical development work remains
  and a work plan is being formulated

66
Robert Brown, P.E. FFS Team Leader 216-283-6015 rg
brown_at_equityeng.com 20600 Chagrin Blvd. Suite
1200 Shaker Heights, OH 44122 USA Phone
216-283-9519 Fax [phone] www.equityeng.com