scholarly journals Overview of French Proposal of Updated Austenitic SS Fatigue Curves and of a Methodology to Account for EAF

2015 ◽  
Author(s):  
Thomas Métais ◽  
Stéphan Courtin ◽  
Pierre Genette ◽  
Laurent De Baglion ◽  
Cédric Gourdin ◽  
...  
Keyword(s):  
Environmental Effects ◽  
Stainless Steels ◽  
Austenitic Stainless Steels ◽  
Fatigue Curve ◽  
Penalty Factor ◽  
Asme Code ◽  
The Mean ◽  
The One

Environmentally Assisted Fatigue is receiving nowadays an increased level of attention not only for new builds but also for the installed bases which are currently having their lives extended to 60 years in various countries. To formally integrate these effects, some international codes have already proposed code cases. More specifically, the ASME code has used the NUREG/CR-6909 [1] as the basis for Code Case N-792 [2] and suggests a modification of the austenitic stainless steels fatigue curve combined with a calculation of an environmental penalty factor, namely Fen, which is to be multiplied by the usual fatigue usage factor. The various methodologies proposed are not finalized and there is still a significant level of discussion as can be illustrated by the recent update of NUREG/CR-6909 [3]. In this context, EDF, AREVA and the CEA have also submitted two RCC-M Rules in Probatory Phase (RPP) (equivalent to ASME code-cases) to AFCEN to propose respectively an update of the fatigue curve for austenitic stainless steels and a methodology to incorporate EAF in fatigue evaluations. The approach is globally similar to the one in the ASME code: it consists in an update of the mean air and design fatigue curves as well as the calculation of an environmental penalty factor. Nevertheless, the methodologies differ in their detailed implementation by especially introducing the Fen-integrated which accounts for the environmental effects already covered by the fatigue curves. This paper is the sequel to the proposal already described in [4] [6].

Status of the French Methodology Proposal for Environmentally Assisted Fatigue Assessment

2014 ◽  
Author(s):  
Thomas Métais ◽  
Stéphan Courtin ◽  
Pierre Genette ◽  
Laurent De Baglion ◽  
Cédric Gourdin ◽  
...  
Keyword(s):  
Fatigue Curve ◽  
Fatigue Assessment ◽  
Penalty Factor ◽  
Asme Code ◽  
The Mean ◽  
The One

Environmentally Assisted Fatigue is receiving nowadays an increased level of attention for new builds and also for installed bases which are currently having their lives extended to 60 years in various countries. To formally integrate these effects, some international codes have already proposed code cases. More particularly, the ASME code has based itself on the NUREG/CR-6909 [1] to elaborate the Code Case N-792 [2] and suggests a modification of the fatigue curve combined with a calculation of an environmental penalty factor, namely Fen, which is to be multiplied by the usual fatigue usage factor. In France, EDF and AREVA also aim at more explicitly integrating these effects in the RCC-M code. The initiative is technically supported by CEA and bases itself on international methodologies but also on results from French in-house testing campaigns [3] [4]. The approach is globally similar to the one in the ASME code: it will indeed consist in an update of the mean air and design fatigue curves as well as the calculation of an environmental penalty factor. Nevertheless, the methodologies differ in their detailed implementation, as was already hinted in previous papers discussing the French methodology [5] [6]. This paper is the sequel to the proposal already described in [7].

French Methodology Proposal for Environmentally Assisted Fatigue Assessment

2013 ◽  
Author(s):  
Thomas Métais ◽  
Stéphan Courtin ◽  
Pierre Genette ◽  
André Lefrançois ◽  
Jean-Paul Massoud ◽  
...  
Keyword(s):  
Life Time ◽  
Fatigue Curve ◽  
Life Extension ◽  
The Past ◽  
Nuclear Plants ◽  
Penalty Factor ◽  
The World ◽  
Asme Code ◽  
Significant Life ◽  
The One

Environmental assisted fatigue is a phenomenon that has been investigated over the past 30 years through many test campaigns in various laboratories around the world. It is receiving nowadays an increased level of attention as many nuclear plants will see their life-time extended to up to 60 years. To provide a set of rules for this significant life extension, international codes have already proposed code cases to formally integrate these effects. More particularly, the ASME code has based itself on the NUREG/CR-6909 [1] to elaborate the Code Case N-792 [2] and suggests a modification of the fatigue curve combined with a calculation of an environmental penalty factor, namely Fen, which multiplies the typical usage factor. In France, the EDF and AREVA objective is also to more explicitly integrate these effects in the RCC-M code basing itself on international methodologies but also results from French in-house testing campaigns [3]. The approach in this paper is globally similar to the one in the ASME code: it will indeed consist in an update of the fatigue curve as well as the calculation of an environmental penalty factor. Nevertheless, the methodologies differ in their detailed implementation, as was already hinted in previous papers discussing the French methodology [4–5]. This paper will present the proposal as well as highlight the differences with the ASME methodology.

Development of a Fatigue Design Curve for Austenitic Stainless Steels in LWR Environments: A Review

2002 ◽  
Author(s):  
Omesh K. Chopra
Keyword(s):  
Stainless Steels ◽  
Pressure Vessel ◽  
Type Strain ◽  
Nuclear Power ◽  
Austenitic Stainless Steels ◽  
Environmental Parameters ◽  
Light Water Reactor ◽  
Code Design ◽  
Fatigue Design ◽  
Asme Code

The ASME Boiler and Pressure Vessel Code provides rules for the construction of nuclear power plant components and specifies fatigue design curves for structural materials. However, the effects of light water reactor (LWR) coolant environments are not explicitly addressed by the Code design curves. Existing fatigue strain–vs.–life (ε–N) data illustrate potentially significant effects of LWR coolant environments on the fatigue resistance of pressure vessel and piping steels. This paper reviews the existing fatigue ε–N data for austenitic stainless steels in LWR coolant environments. The effects of key material, loading, and environmental parameters, such as steel type, strain amplitude, strain rate, temperature, dissolved oxygen level in water, and flow rate, on the fatigue lives of these steels are summarized. Statistical models are presented for estimating the fatigue ε–N curves for austenitic stainless steels as a function of the material, loading, and environmental parameters. Two methods for incorporating environmental effects into the ASME Code fatigue evaluations are presented. Data available in the literature have been reviewed to evaluate the conservatism in the existing ASME Code fatigue design curves.

scholarly journals PWR Effect on Crack Initiation Under Equi-Biaxial Loading Development of the Experiment

2016 ◽  
Author(s):  
G. Perez ◽  
C. Gourdin ◽  
S. Courtin ◽  
J. C. Le Roux
Keyword(s):  
Biaxial Loading ◽  
Austenitic Stainless Steels ◽  
Fatigue Curve ◽  
Structural Effect ◽  
Fatigue Tests ◽  
Fatigue Lifetime ◽  
New Device ◽  
Fatigue Design ◽  
Penalty Factor ◽  
Mean Strain

Fatigue lifetime assessment is essential in the design of structures. Under-estimated lifetime predictions may generate overly conservative usage factor values and hence result in unnecessary in-service inspections. In the framework of upgrading the fatigue design rules (RCC-M, RCC-MRx), the uniaxial reference fatigue curve was altered by taking into account effects like: Multiaxiality, Mean stress or strain, Surface roughness (polished or ground), Scale effect, Loading History... In addition to this effect, Environmentally Assisted Fatigue is also receiving nowadays an increased level of attention. To formally integrate these effects, some international codes have already proposed and suggested a modification of the austenitic stainless steels fatigue curve combined with a calculation of an environmental penalty factor, namely Fen, which has to be multiplied by the usual fatigue usage factor. The aim of this paper is to present a new device “FABIME2E” developed in the LISN in collaboration with EDF and AREVA. These new tests allow quantifying accurately the effect of PWR environment on semi-structure specimen. This new device combines the structural effect like equibiaxiality and mean strain and the environmental penalty effect with the use of PWR environment during the fatigue tests.

Statistical Analyses of High Cycle Fatigue French Data for Austenitic SS

2014 ◽  
Author(s):  
Géraud Blatman ◽  
Thomas Métais ◽  
Jean-Christophe Le Roux ◽  
Simon Cambier
Keyword(s):  
Strain Amplitude ◽  
High Cycle Fatigue ◽  
Experimental Testing ◽  
Austenitic Stainless Steels ◽  
Fatigue Curve ◽  
Statistical Analyses ◽  
Starting Point ◽  
The Mean ◽  
Number Of Cycles ◽  
Selection Of

In the 2009 version of the ASME BPV Code, a set of new design fatigue curves were proposed to cover the various steels of the code. These changes occurred in the wake of publications [1] showing that the mean air curve used to build the former ASME fatigue curve did not always represent accurately laboratory results. The starting point for the methodology to build the design curve is the mean air curve obtained through laboratory testing: coefficients are then applied to the mean air curve in order to bridge the gap between experimental testing and reactor conditions. These coefficients on the number of cycles and on the strain amplitude are equal to 12 and 2 respectively in the 2009 ASME BPV code, using the mean air curve proposal from NUREG/CR-6909 [1]. Internationally, with the same mean air curve, other proposals have emerged and especially in France [2]-[3] where a consensus seems to be reached on the reduction of the coefficient on strain amplitude. This paper provides statistical analyses of the experimental data obtained in France at high-cycle for austenitic stainless steels. It enables to bring arguments for the selection of a coefficient on strain amplitude in the French RCC-M code, where less scatter on the data is witnessed due to fewer material grades.

Fatigue of Stainless Steel Components: Toward Codified Rules Improvements

2013 ◽  
Author(s):  
Claude Faidy
Keyword(s):  
Stainless Steel ◽  
Fatigue Crack ◽  
Environmental Effects ◽  
Stainless Steels ◽  
High Cycle Fatigue ◽  
Fatigue Curve ◽  
Fatigue Tests ◽  
Correction Factors ◽  
Cycle Fatigue ◽  
The Past

During the past 30 years many fatigue tests and fatigue analysis improvements have been developed in France in order to improve Codified Fatigue Rules of French Nuclear Codes: RCC-M, RSE-M and RCC-MRx. This paper will present comments and proposals for development of these rules associated to Gaps and Needs in order to finalize and justify the AFCEN Codes new rules. Recently 3 new international R&D results confirm possible un-conservative fatigue material data: - High cycle fatigue in air for stainless steel, - Environmental effects on fatigue S-N curve for all materials, and in particular stainless steels, - Fatigue Crack Growth law under PWR environment for stainless steel. In front of these new results, AFCEN is working on a 1st set of rules based on existing knowledge: - Air fatigue curve: mean and design - PWR Environmental effects with detrimental correction factors A periodic up-dating of AFCEN proposed rules will be done using French and International R&D programs with a particular attention on harmonization with other Code rules developed in USA, Japan and Germany, in particular.

JSME Construction Standard for Superconducting Magnet of Fusion Facility “Procedure for Structural Design”

2009 ◽  
Author(s):  
Yukio Takahashi ◽  
Shigeru Tado ◽  
Kazunori Kitamura ◽  
Masataka Nakahira ◽  
Junji Ohmori ◽  
...  
Keyword(s):  
Stainless Steels ◽  
Structural Design ◽  
Structural Integrity ◽  
Superconducting Magnets ◽  
Austenitic Stainless Steels ◽  
Superconducting Magnet ◽  
Fatigue Curve ◽  
Stress System ◽  
Allowable Stress ◽  
Fatigue Assessment

Superconducting magnets are structures which have an important role in Tokamak-type fusion reactor plants. They are huge and complicated structures exposed to very low temperature, 4K and the methods for keeping their integrity need to be newly developed. To maintain their structural integrity during the plant operation, a procedure for structural design was developed as a part of JSME Construction Standard for Superconducting Magnet. General structures and requirements of this procedure basically follow those of class 1 and class 2 components in light water reactor plants as specified in Section III, Division 1 of the ASME Boiler and Pressure Vessel Code, and include the evaluation of primary stress, secondary stress and fatigue damage. However, various new aspects have been incorporated considering the features of superconducting magnet structures. They can be summarized as follows: (i) A new procedure to determine allowable stress intensity value was employed to take advantage of the excellent property of newly developed austenitic stainless steels. (ii) Allowable stress system was simplified considering that only austenitic stainless steels and a nickel-based alloy are planned to be used. (iii) A design fatigue curve at 4K was developed for austenitic stainless steels. (iv) In addition to the conventional fatigue assessment based on design fatigue curves, guidelines for fatigue assessment based on crack growth prediction were added as a non-mandatory appendix to provide a tool of assurance for welded joints which are difficult to evaluate nondestructively during the service.

Contributions of Dr. Sumio Yukawa in the Development of Non-Ductile Failure Prevention Rules in the ASME Code

2008 ◽  
Author(s):  
Hardayal S. Mehta
Keyword(s):  
Elevated Temperature ◽  
Carbon Steel ◽  
Stainless Steels ◽  
Pressure Vessel ◽  
Nickel Alloys ◽  
Ductile Failure ◽  
Austenitic Stainless Steels ◽  
Current Status ◽  
Asme Code

The objective of this paper is to review and highlight the contributions of Dr. Sumio Yukawa in the development of rules for the prevention of non-ductile failure in the ASME Boiler and Pressure Vessel Code. This includes review of his role in the development of WRC-175, Appendix G of Section III, the development of early flaw evaluation rules for carbon steel piping and in the review and evaluation of the toughness of austenitic stainless steels and nickel alloys after long-term elevated temperature exposures. The current status of these activities is briefly described.

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