Reliability Assessment of Failure Assessment Diagram Based Fitness for Service Procedure Including the Effect of Bias in Modeling

This paper presents the estimation of the reliability levels associated with a cracked pipe found acceptable as per the failure assessment diagram (FAD) based acceptance criteria of ASME Section XI, Appendix H. This acceptance criterion is built on the concepts of fracture mechanics. The parameters which enter the acceptance criteria are piping geometry, applied loading, crack size, and the material properties (tensile and fracture). Most of these parameters are known to exhibit uncertainty in their values. The FAD used also has an associated modeling bias. The code addresses these uncertainties by providing a factor of safety on the applied load. The use of a common factor of safety for a variety of pipe sizes, crack configuration, load combination, and materials may not ensure consistent level of safety associated with the piping component being evaluated. This level of safety can be evaluated by using structural reliability concepts. This paper analyzes the reliability level which is achieved if a cracked pipe passes the acceptance criteria prescribed by the code. The reliability is evaluated for a range of pipe and crack geometry, different load combination, and different materials using Monte Carlo method. The realistic assessment of reliability also requires the assessment of modeling bias associated with the FAD. This bias is also evaluated using the results from the published fracture experiments.

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Constraint in the Failure Assessment Diagram Approach for Fracture Assessment

Journal of Pressure Vessel Technology ◽

10.1115/1.2842121 ◽

1995 ◽

Vol 117 (3) ◽

pp. 260-267 ◽

Cited By ~ 58

Author(s):

R. A. Ainsworth ◽

N. P. O’Dowd

Keyword(s):

Crack Size ◽

Structural Constraint ◽

Failure Assessment Diagram ◽

Failure Assessment ◽

T Stress ◽

Fracture Assessment ◽

The Subject ◽

Constraint Effects ◽

Two Parameters ◽

Diagram Approach

This paper presents a framework for including constraint effects in the failure assessment diagram approach for fracture assessment. As parameters for describing constraint are still the subject of development, the framework is illustrated using both the elastic T-stress and the hydrostatic Q-stress. It is shown that constraint effects can be treated by modifying the shape of the failure assessment curve. In their simplest form, the modifications involve only two parameters: one quantifying the magnitude of structural constraint which depends on geometry and crack size; and the second quantifying the influence of constraint on fracture toughness.

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Comparison of Numerical Integration and Monte Carlo Simulation Methods for Structural Reliability based on the Failure Assessment Diagram

10.20906/cps/cilamce2015-0416 ◽

2015 ◽

Author(s):

Alexandre Francisco ◽

Jorge Alberto Duran ◽

Carolina Vilela ◽

Tiago do Nascimento Simões

Keyword(s):

Monte Carlo Simulation ◽

Monte Carlo ◽

Numerical Integration ◽

Structural Reliability ◽

Simulation Methods ◽

Failure Assessment Diagram ◽

Failure Assessment

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Integrity Assessment of Defected Structure at High Temperature With a Material Database

ASME 2010 Pressure Vessels and Piping Conference: Volume 6, Parts A and B ◽

10.1115/pvp2010-25572 ◽

2010 ◽

Author(s):

Zhengdong Wang ◽

Fu-Zhen Xuan ◽

Shan-Tung Tu

Keyword(s):

High Temperature ◽

Crack Size ◽

Pressure Vessels ◽

Time Dependent ◽

Integrity Assessment ◽

Failure Assessment Diagram ◽

Base Materials ◽

Axial Tension ◽

Failure Assessment ◽

Dependent Failure

The basic theory of Time Dependent Failure Assessment Diagram (TDFAD) is introduced in this paper to be modified for cracks in mismatched welds at high temperature. A time-dependent failure assessment curve is constructed using the method of R6 Option 2. This curve depends not only on the geometry and crack size but also on the mechanical properties of both weld and base materials. The application of such an approach is given to an internal circumferentially defected welded-cylinder under axial tension. An engineering tool of integrity assessment for defected structure at high temperature has been developed for a decade based on the Time Dependent Failure Assessment Diagram (TDFAD) technology for pressure vessels. The software is illustrated in this paper by framework and interfaces and some industrial cases are introduced to show the procedure of the assessment by using the software. A high temperature material database (HTMD) of main properties for typical high temperature steels and alloys is constructed to meet the needs of the safety assessment of the pressure vessels and other structures. The structure of the database is shown in the paper with some tables and charts.

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Estimation of the V-Factor for Circumferentially Cracked Pipes Under Combined Thermal and Mechanical Stresses Using a Strain-Based Failure Assessment Diagram

ASME 2011 Pressure Vessels and Piping Conference: Volume 3 ◽

10.1115/pvp2011-57599 ◽

2011 ◽

Author(s):

Chang-Young Oh ◽

Yun-Jae Kim ◽

Dong-il Ryu ◽

P. J. Budden ◽

R. A. Ainsworth

Keyword(s):

Finite Element ◽

Thermal Load ◽

Thermal Stresses ◽

Mechanical Stresses ◽

Estimation Methods ◽

Finite Element Analyses ◽

3 Dimensional ◽

Failure Assessment Diagram ◽

Failure Assessment ◽

Dimensional Finite Element

This paper presents finite element solutions for elastic-plastic J for circumferentially cracked pipes under combined mechanical and thermal loads in terms of the V/Vo factor used within a strain-based failure assessment diagram. In this study, 3-dimensional finite element analyses are conducted to calculate the V-factor under combined mechanical and thermal load. It is found that estimation of V/Vo is sensitive to the method used for its evaluation. For larger thermal stresses, currently proposed estimation methods are overly conservative.

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Defective Pipeline Fatigue-Life Prediction Using Failure Assessment Diagram Technique

2004 International Pipeline Conference, Volumes 1, 2, and 3 ◽

10.1115/ipc2004-0487 ◽

2004 ◽

Author(s):

Jinheng Luo ◽

Xinwei Zhao ◽

Qingren Xiong ◽

Chunyong Huo

Keyword(s):

Fatigue Life ◽

Evaluation System ◽

Life Prediction ◽

Safety Evaluation ◽

Load Ratio ◽

Test System ◽

Full Scale ◽

Oil Pipeline ◽

Failure Assessment Diagram ◽

Failure Assessment

The life prediction, whose results can be used to define the inspection, repair or replacement cycle of in-service pipeline, is a main component of safety assessment of gas and oil pipeline. At present, failure Assessment Diagram (FAD) technique has been widely used in quantitative engineering safety evaluation system of pipeline that contains crack-like flaws. In past work, the authors developed a very useful model to predict the fatigue life of defective pipeline and established a computer calculating method. Based on FAD technique, toughness ratio and load ratio are calculated repeatedly with every crack increment in the model. With the self-developed full-scale test system, the full-scale pipe fatigue test was collected to verify the applicability of this method.

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Assessment of undercut defect in a laser welded plate made of Ti–6Al–4V titanium alloy with probabilistic domain failure assessment diagram

Engineering Failure Analysis ◽

10.1016/j.engfailanal.2015.11.018 ◽

2016 ◽

Vol 59 ◽

pp. 17-27 ◽

Cited By ~ 5

Author(s):

S. Jallouf ◽

K. Casavola ◽

C. Pappalettere ◽

G. Pluvinage

Keyword(s):

Titanium Alloy ◽

Failure Assessment Diagram ◽

Failure Assessment

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Development of Flaw Acceptance Criteria for Aging Management of Spent Nuclear Fuel Multiple-Purpose Canisters

Volume 6A: Materials and Fabrication ◽

10.1115/pvp2015-45935 ◽

2015 ◽

Author(s):

Poh-Sang Lam ◽

Robert L. Sindelar

Keyword(s):

Residual Stress ◽

Nuclear Fuel ◽

Spent Nuclear Fuel ◽

Storage Period ◽

Limit Load ◽

American Petroleum Institute ◽

Acceptance Criteria ◽

Long Term Storage ◽

Flaw Tolerance ◽

Failure Assessment

A typical multipurpose canister (MPC) is made of austenitic stainless steel and is loaded with spent nuclear fuel assemblies. The canister may be subject to service-induced degradation when it is exposed to aggressive atmospheric environments during a possibly long-term storage period if the permanent repository is yet to be identified and readied. Because heat treatment for stress relief is not required for the construction of an MPC, stress corrosion cracking may be initiated on the canister surface in the welds or in the heat affected zone. An acceptance criteria methodology is being developed for flaw disposition should the crack-like defects be detected by periodic Inservice Inspection. The first-order instability flaw sizes has been determined with bounding flaw configurations, that is, through-wall axial or circumferential cracks, and part-through-wall long axial flaw or 360° circumferential crack. The procedure recommended by the American Petroleum Institute (API) 579 Fitness-for-Service code (Second Edition) is used to estimate the instability crack length or depth by implementing the failure assessment diagram (FAD) methodology. The welding residual stresses are mostly unknown and are therefore estimated with the API 579 procedure. It is demonstrated in this paper that the residual stress has significant impact on the instability length or depth of the crack. The findings will limit the applicability of the flaw tolerance obtained from limit load approach where residual stress is ignored and only ligament yielding is considered.

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