Slide 1
Presentation Overview Introduction to Fitness for
Service(FFS)Overview of API 579/ ASME FFS-1 Assessment of
Crack-Like FlawsStudy GoalsReferences6 February 2011Petroleum
University of Technology, Abadan Institute of
Technology2Introduction to Fitness for Service(FFS)6 February
2011Petroleum University of Technology, Abadan Institute of
Technology3Overview of API 5796 February 2011Petroleum University
of Technology, Abadan Institute of Technology13Definition of
Fitness-For-Service (FFS)6 February 2011Petroleum University of
Technology, Abadan Institute of TechnologyQuantitative engineering
evaluations that are performed to demonstrate the structural
integrity of an in-service component that may contain a flaw or
damage.[2]4It can be used for equipments that are not in-serviceBut
FITNET has a different Definition
4Where is FFS Assessment Applicable?Oil and Gas Industry
6 February 2011Petroleum University of Technology, Abadan
Institute of Technology51-Prepare sutable Pictures5Where is FFS
Assessment Applicable?Fossil Fuel UtilityNuclear Power Plant
6 February 2011Petroleum University of Technology, Abadan
Institute of Technology6
1-Prepare sutable Pictures6Where is FFS Assessment
Applicable?Pulp & Paper IndustryFood Processing Industry
6 February 2011Petroleum University of Technology, Abadan
Institute of Technology
71-Prepare sutable Pictures7When is FFS Assessment Needed?Asset
having Damages : such as metal loss, distortion , laminations,
cracking ,blisters, etc.Asset lacks original design information or
exceeded its useful life.
8When is FFS Assessment Needed?Asset that have undergone any
event that might have affected its serviceability like: fire
Decommissioned asset that may be used in a different service
6 February 2011Petroleum University of Technology, Abadan
Institute of Technology9
Benefits of FFS
Safe and reliable operation Reduce Unnecessary repairsReduce
costsOperation of aging facilities6 February 2011Petroleum
University of Technology, Abadan Institute of Technology101.10FFS
StandardsStandard NamePublisher
Date of FirstReleaseAPI 579-1/ASME FFS-1API & ASME 2000
(Joint 2007)BS-7910BSI1999PD 6493(Withdrawn)BSI1980NUCLEAR ELECTRIC
R5BRITISH ENERGY1990NUCLEAR ELECTRIC R6BRITISH
ENERGY1976FITNETEuropean Fitness-For-Service Network20066 February
2011Petroleum University of Technology, Abadan Institute of
Technology1111FFS Softwares6 February 2011Petroleum University of
Technology, Abadan Institute of Technology12Software
NamePublisherDate of First ReleaseSignal Fitness-For- ServiceQuest
Integrity Group1997CrackwiseTWI 2005 ENGFITTWI2007R-Code British
Energy1990R-STRENGPRCI1989FFS MASTERPUT2010 Background to API
579First Edition Published in 2000 as API RP 579 Recommended
Practice Second Edition Published in 2007 as API 579-1/ASME FFS-1
StandardExample Problems Published in 2009 as API 579-2/ASME FFS-2
Standard6 February 2011Petroleum University of Technology, Abadan
Institute of Technology1414Overview of API 579- PartsPart 1,2:
IntroductionPart 3: Brittle Fracture
Part 4: General Metal Loss
Part 5: Local Metal Loss
Part 6: Pitting Corrosion
Part 7: Hydrogen Blisters and Hydrogen Damage
Part 8: Misalignment and Shell Distortions
Part 9: Crack-Like Flaws
Part 10: Creep
Part 11: Fire Damage
Part 12: Dents, Gouges, and Dent-Gouge Combinations
Part 13: Lamination
6 February 2011Petroleum University of Technology, Abadan
Institute of Technology15Annexes: A-KGeneral Assessment Procedure6
February 2011Petroleum University of Technology, Abadan Institute
of TechnologyFlaw and Damage Mechanism IdentificationApplicability
and Limitations Data RequirementsAssessment Techniques and
Acceptance CriteriaRemaining Life EvaluationRemediationIn-Service
MonitoringDocumentation1616Assessment Levels6 February
2011Petroleum University of Technology, Abadan Institute of
Technology17 Level1 Conservative screening Minimum amount of
inspection or component information Plant inspection or engineering
personnelLevel2 More detailed less conservative with more accurate
results Inspection information Qualified engineering
personnelLevel3The most detailed evaluation The most detailed
inspection and component information Recommended analysis
procedures based on material testing and /or numerical analysis
techniques such as the finite element MethodPersonnel with
expertise in Complex FFS Assessments17NoEvaluation Techniques6
February 2011Petroleum University of Technology, Abadan Institute
of Technology18Level1Perform AssessmentFit for
Service?Rerate?Increase Assessment Level?Document ResultsRepair,
ReplaceOr Retire EquipmentReturn Equipment to ServiceDocument
ResultsDetermine Reduced Pressure and/or TemperatureLevel 2 or
3StartAssessmentYesYesYesNoNoCrack-Like Flaws are Planar Flaws that
are Predominantly Characterized by a Length and Depth, with a Sharp
Root Radius.
2 c2a t6 February 2011Petroleum University of Technology, Abadan
Institute of Technology209.1 Flaw and Damage Mechanism
Identification- Definition of Crack-Like Flaws Surface Breaking
Embedded Through-wall
6 February 2011Petroleum University of Technology, Abadan
Institute of Technology9.1 Flaw and Damage Mechanism
Identification- Type of Crack-Like Flaws21
21Planar Flaws: Cracks, Lack of Penetration, Lack of
FusionVolumetric Flaws: Aligned Porosity or Inclusions, Deep
Undercuts ,Root Undercuts ,Overlaps
6 February 2011Petroleum University of Technology, Abadan
Institute of Technology9.1 Flaw and Damage Mechanism
Identification- Example of Crack-Like Flaws22The Component is not
Operating in the Creep Range Dynamic Loading Effects are not
SignificantThe Crack-like Flaw Does not Grow in Service.1)
Limitations on Component and Flaw Geometries2) Limitations on
Component Loads3) Limitations on Material PropertiesLimitations of
Level 1 AssessmentLimitations of Level 2 Assessment6 February
2011Petroleum University of Technology, Abadan Institute of
Technology9.2 Applicability and Limitation of Procedures239.3.1
General9.3.2 Original Equipment Design Data 9.3.3 Maintenance and
Operating History 9.3.4 Loads and Stresses 9.3.5 Material
Properties9.3.6 Flaw Characterization9.3 Data Requirements6
February 201124Petroleum University of Technology, Abadan Institute
of Technology9.3.6.1 Overview9.3.6.2 Characterization of Flaw
Length9.3.6.3 Characterization of Flaw Depth9.3.6.4
Characterization of Branched Cracks9.3.6.5 Characterization of
Multiple Flaws9.3.6.6 Recategorization of Flaws
6 February 2011Petroleum University of Technology, Abadan
Institute of Technology9.3 Data Requirements9.3.6 Flaw
Characterization25259.3.6-Flaw Characterization9.3.6.2
Overview26
Ideal Shape for Crack Like FlawsThe flaw characterization rules
allow crack geometry to be modeled by a geometrically simpler one
in order to make the actual crack geometry more amenable to
fracture mechanics analysis266 February 2011Petroleum University of
Technology, Abadan Institute of Technology27
Ideal Shape for Crack Like Flaws2727
9.3.6-Flaw Characterization9.3.6.2 Characterization of Flaw
Length28If the flaw is oriented perpendicular to the plane of the
maximum principal tensile stress in the componentc =cm ( or 2cm =
2c ) . If the flaw is not oriented in a principal plane, then an
equivalent flaw dimension shall be determined by one of the
following options.a)Option 1 The flaw dimension, c , to be used in
the calculations shall be set equal to the measured length, cm ,
irrespective of orientation.For fracture assessments, the plane of
the flaw shall be assumed to be normal to the maximum principal
tensile stress.
b)Option 2 The procedure for defining an equivalent Mode I flaw
dimension is shown in Figure 9.2.
28Figure 9.2 Procedure for Defining an Effective Flaw Length on
a Principal Stress Plane
29299.3.6-Flaw Characterization9.3.6.3 Characterization of Flaw
Depth6 February 2011Petroleum University of Technology, Abadan
Institute of Technology30a)Flaw Depth by Default ValuesThrough-Wall
Flaw : a conservative assumption is that the flaw penetrates the
wall (i.e., a = t for a surface flaw).
2) Surface Flaw a= min [t,c]
30319.3.6-Flaw Characterization9.3.6.3 Characterization of Flaw
DepthProject The flaw onto the principal planea=Wam, W is
determined using Equation 9.7 or Figure9.5
31
Determination of W from formula or Curve
3232
9.3.6-Flaw Characterization9.3.6.4 Characterization of Branched
Cracks6 February 2011Petroleum University of Technology, Abadan
Institute of Technology33339.3.6-Flaw Characterization9.3.6.4
Characterization of Branched Cracks6 February 2011Petroleum
University of Technology, Abadan Institute of Technology34
349.3.6-Flaw Characterization9.3.6.5 Characterization of
Multiple Cracks6 February 2011Petroleum University of Technology,
Abadan Institute of Technology35
a)If two or more flaws are close to one another, they can be
combined into a single equivalent flaw for the purpose of analysis.
If the separation distance is sufficient to avoid interaction, then
the flaws can be analyzed independently, and only the worst-case
flaw needs to be considered.
b)Multiple flaws do not have to be combined into an equivalent
flaw for evaluation if a stress intensity factor and limit load
solution can be obtained for the interacting flaw geometries.
1)STEP 1 Rotate each flaw so that it coincides with a principal
plane, and determine the effective flaw length according to the
procedure in paragraph 9.3.6.2. All flaws in the local region
should nowbe parallel, as illustrated in Figure 9.7(b).2)STEP 2
Apply the criteria in Figure 9.8 to check for interaction between
parallel flaws. Project allinteracting flaws onto a single plane,
as illustrated in Figure 9.7(c). Note that some flaws will be
combined using this procedure.3)STEP 3 Estimate the depth of the
flaws with the procedure outlined in paragraph 9.3.6.3. If two or
more flaws were combined because of STEP 2 above, define the depth,
a , as the width of a rectangle inscribed around the combined flaw,
as illustrated in Figure 9.7(d).4)STEP 4 Apply the criteria in
Figure 9.8 to check for interaction between flaws on a given plane.
If interaction exists, the dimensions of the combined flaw are
inferred from a rectangle inscribed around the interacting
flaws.
35
9.3.6-Flaw Characterization9.3.6.5 Characterization of Multiple
Cracks6 February 2011Petroleum University of Technology, Abadan
Institute of Technology3636
6 February 2011Petroleum University of Technology, Abadan
Institute of Technology9.3.6-Flaw Characterization9.3.6.6 Flaw
Recategorization Guidelines37Flaw recategorization is required for
two reasons.a) For an embedded flaw close to the surface or for a
deep surface flaw where the remaining ligament is small, the
results obtained in the assessment may be overly conservative
because the reference stress (see Annex D) in the remaining
ligament may over estimate the plasticity effects on the crack
driving force resulting in the assessment point falling outside of
the failure assessment diagram. Recategorization of an embedded
flaw to a surface flaw, or a surface flaw to a through-wall flaw,
may result in the associated assessment point being inside of the
failure assessment diagram.b) Most of the stress intensity
solutions in Annex C are not accurate for very deep cracks due to
high strain/plasticity effects. For example, the commonly published
KI solutions for a semi-elliptical surface flaw are only accurate
for a/t 6 mm (0.25 in) , then the 1-t screening curves shall be
used.
Note: Crack dimension for a 1-t and -t flaw are shown in Annex
C, Figures C.10 & C.14.
41
42Flaw DimensionsStress AnalysisMaterial ToughnessKmatStress
Intensity Factor Solutions, KPI & KSRI
Flaw DimensionsStress AnalysisReference Stress Solutions,
PrefMaterial Yield Strength, ysAcceptable RegionAssessment
PointUnacceptable Region
LrKr42Developing a Fitness-For-Service Software Package for
Assessment of Crack-like Flaws According to Part 9 of
API579Implementation and Validation of SoftwareCase
StudyInvestigating the Technical Basis and Validation of Methods
Proposed in API 579, Part 9Proposing Suitable Methods for Level 3
AssessmentRecommendations for Improving Upon Existing
MethodologiesStudy Goals6 February 2011Petroleum University of
Technology, Abadan Institute of Technology441- Come one After
Another2-Apply Suitable Pictures44References [1] 1388[2]
Fitness-For-Service, API 579-1/ASME FFS-1,Second Edition, American
Petroleum Institute and The American Society of Mechanical
Engineers, Washington, D.C., JUNE 5, 2007.[3] introduction to
Fitness-For-Service (FFS) Assessment Using API/ASME Standard API
579-1 / ASME FFS-1,Webinar Series, Lloyds Register Group, April 22,
2010[4] API 579: a comprehensive fitness-for-service guide, Ted L.
Anderson, David A. Osage, Structural Reliability Technology, 1898 S
Flatiron Court, Suite 235, Boulder, CO 80301, USA[5]
http://www.fitness4service.com/[6] http://www.questintegrity.com/6
February 2011Petroleum University of Technology, Abadan Institute
of Technology46Question?To look is one thing, To see what you are
looking at is something else, To understand what you see is
another, To learn from what you understand is another, But, To act
on what you learn is all that really matter!Winston Churchill6
February 2011Petroleum University of Technology, Abadan Institute
of TechnologyTHANK YOU6 February 2011Petroleum University of
Technology, Abadan Institute of Technology48
