bluuebunny/crossref_metadata_2025_split huggingface dataset:
Compressor General Arrangement Dynamic Design Guided by Preliminary Cylinder Manifold Forced Response
Authors: Passeri Marco , Bagagli Riccardo , Maggi Carmelo 
Published: November 2015

Today market requires machinery with ever larger performance increasing compression system vibrations risks. Knowledge of dampers pulsation-forces phenomena and best practices allows their minimization. Loads acting on foundation are early defined allowing a proper design, while “Cylinder-Gas-loads” depending upon compressor data-sheet cannot be adjusted unless to change requirements. Considering their high amplitudes and frequencies spectrum, some exciting frequencies often coincides with system mechanical natural frequencies.
This involves expensive efforts in preliminary Cylinder Manifold response studies to guide compressor General Arrangement design. Specific software that includes Compressor standard elements selection and that allow building dampers by parametric inputs is cost effective in model creation. Together with the cost benefits it facilitates the designer to simulate multiple configurations rebuilding the model in a short time and exploring several solutions to optimize the system vibration control.
A FEM specialist is not required for the Model build-up, the Software allow automatically applying cylinder gas loads, run analysis and compare results vs allowable ones. In case of allowable limits exceeding or design changes, G&A Designer can easily change input and iterate the loop till satisfactory results are achieved in a timely and quality manner, optimizing dampers and supports.
Validation of ACE Analytical Criterion for Warm Pre-Stress Evaluation in RPV Integrity Assessment
Authors: Moinereau Dominique , Landron Caroline , Chapuliot Stéphane , Marie Stéphane 
Published: November 2015

Numerous experimental and numerical studies have been conducted in France to demonstrate the beneficial effect of warm pre-stress (WPS) on the brittle fracture resistance of reactor pressure vessel (RPV) steels and take into account this effect in French RPV integrity assessment. A large panel of experimental data is available, obtained on small, medium and large scale specimens. These data have been included in a specific EDF WPS experimental database.
An analytical criterion — ACE criterion — is proposed by French organizations (AREVA, CEA and EDF) for analytical evaluation of warm pre-stress effect on the brittle resistance of RPV steels.
After a description of ACE criterion and the EDF WPS database, the validation of the criterion is shown — based on this database — by comparison between experimental results and predictions of the model.
Proposed Changes to the ASME Boiler and Pressure Vessel Code Section III Appendix N for Flow-Induced Vibrations
Authors: Banyay Gregory A. , Meyer Gregory A. , Walker Adam P. 
Published: November 2015

This article outlines changes proposed for implementation in the ASME Boiler and Pressure Vessel Code Section III Appendix N pertaining to Flow-Induced Vibrations (FIV). Several portions of Appendix N were originally written multiple decades ago and are not necessarily readily prescriptive for present-day analyses. An ASME Task Group on Flow-Induced Vibrations has been formed to identify areas of improvement to Appendix N so that the Appendix may be more useable in present-day FIV analyses, and a means of establishing consensus for characterization of this complex phenomena. This paper identifies opportunities for improvement to portions of Appendix N pertaining to Turbulence, Acoustic, and associated Structural Dynamic Modeling, and Data Processing.
Specific suggestions are made for the following: Characterization of acoustic damping and acoustic harmonic responses, updated considerations for aeroacoustic phenomena, structural damping quantification of nuclear components, systematic approaches to modeling (random) turbulence-induced vibrations (including RMS-to-Peak ratio), considerations for leakage flow-induced instabilities, and opportunities to employ computational methods are discussed. Opportunities for the applicability of data processing algorithms such as the proper orthogonal decomposition and circumferential wavenumber decomposition are also discussed and an updated methodology for combination of random and deterministic loads for FIV analyses is presented.
Phase-Lag-Induced Fluctuating Lift Forces on Two Tandem Bluff Bodies
Authors: Alam Md. Mahbub , Zhe Ma 
Published: November 2015

A numerical simulation at a Reynolds number Re = 200 is conducted to find how flow-induced forces on two tandem circular cylinders is connected to the phase lag between vortex sheddings from the cylinders. The spacing ratio L* (= L/D) is varied from 2 to 9, where L is the cylinder center-to-center spacing and D is the cylinder diameter. Here we mainly focus on fluctuating lift coefficient CLf of the upstream cylinder, vortex dynamics in the gap between cylinders, and phase lag ϕ between the vortex sheddings from the two cylinders for L* larger than the critical where the co-shedding flow prevails. ϕ is indeed nonlinear function of L*, Strouhal number (St) and convection velocity of vortices in the gap between the cylinders. We unearth that the upstream cylinder CLf is affected by both L* and ϕ. While the contribution of L* to CLf diminishes rapidly with L*, that of ϕ makes the L*-dependent CLf variation damped-sinusoidal, persisting in the L* range examined. The inphase and antiphase flows respectively correspond to a local maximum and minimum CLf. How CLf is correlated with L* and ϕ can be deduced as,
C L f = A e −α L * + B e −β L * sin ϕ + π 2 + C ,
where A, α, B, β and C are constants. The physics behind the damped-sinusoidal variation in CLf is discussed.
EDF/NRC High-Cycle Fatigue Database Proposal
Authors: Métais T. P. , Stevens G. , Blatman G. , Le Roux J. C. , Tregoning R. L. 
Published: November 2015

Revised fatigue curves for austenitic stainless steels are currently being considered by several organizations in various countries, including Japan, South Korea, and France. The data available from laboratory tests indicate that the mean air curve considering all available austenitic material fatigue data may be overly conservative compared to a mean curve constructed from only those data representative of a particular type of material. In other words, developing separate fatigue curves for each of the different types of austenitic materials may prove useful in terms of removing excess conservatism in the estimation of fatigue lives.
In practice, the fatigue curves of interest are documented in the various international design codes. For example, in the 2009 Addenda of Section III of the ASME Boiler and Pressure Vessel (BPV) Code [1], a revised design air fatigue curve for austenitic materials was implemented that was based on NRC research models [2]. More recently, in Japan, various industrial groups have joined their efforts to create the Design Fatigue Curve Sub-committee (DCFS) with the objective to reassess the fatigue curves [3]. In France, EDF/AREVA and CEA are developing a new fatigue curve for austenitic stainless steels [4]. More specifically, in 2014, EDF presented a paper on high-cycle fatigue analysis which demonstrated that the factor on the strain amplitude could be reduced from 2 to 1.4 for the RCC-M austenitic stainless steel grades [5].
Recently, discussions between EDF and the U.S. Nuclear Regulatory Commission (NRC) have led both parties to recognize that there is a need to exchange worldwide research data from fatigue testing to promote a common, vetted database available to all researchers. These discussions have led EDF and NRC to pursue a collaborative agreement and associated fatigue data exchange, with the intent to assemble all available fatigue data for austenitic materials into a standardized format. The longer term objective is to perform common analyses on the consolidated set of data.
This paper summarizes the intent and of the preliminary results of this cooperation and also provides insights from both organizations on possible future activities and participation in the global exchange of fatigue research data.
Overview of French Proposal of Updated Austenitic SS Fatigue Curves and of a Methodology to Account for EAF
Authors: Métais Thomas , Courtin Stéphan , Genette Pierre , De Baglion Laurent , Gourdin Cédric , Le Roux Jean-Christophe 
Published: November 2015

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].
Computational Methods to Support Brittle Fracture Assessment of PSVs Involving Autorefrigeration
Authors: Subramanian Kannan , Penso Jorge , Pordal Harbi 
Published: November 2015

Pressure safety relief valve (PSV) operation generally leads to cooling of the valve itself and the piping connected to the PSV. The temperatures may reach values below the minimum design metal temperature (MDMT) of the valve, and therefore the valve needs to be assessed for brittle fracture susceptibility. Simplistic determination of the minimum metal temperature in the valve may disqualify these valves during the brittle fracture assessments (BFA). Replacement may be time consuming and may not be cost effective. In such circumstances, a sophisticated and more representative BFA approach involving the use of computational fluid dynamics (CFD) followed by finite element method (FEM) based stress analysis which may be further followed by fracture mechanics can be adopted based on the concepts defined in ASME/API 579.
The accuracy of the BFA depends on the accuracy of each of the computational method involved in the assessment. Among all the computational methods, CFD poses significant challenge. The low temperature may have been caused due to Joule-Thompson effect or auto-refrigeration. While Joule-Thompson effect can be best captured with easy to implement and robust CFD methods, auto-refrigeration involving adiabatic flashing which causes additional complexity and requires multiple sensitivity studies performed to determine the accuracy of the CFD approach. In this paper, an overview of the computational methods used in the brittle fracture assessment of PSVs is presented. Specific CFD method details are provided for PSV involving the flashing of liquid hydrocarbon to vapor is presented in the form of a case study derived from downstream industry application.
Low Cycle Fatigue Behavior in Air and in PWR Water of Type 304L and 316L Austenitic Stainless Steels Manufactured by Hot Isostatic Pressing Process
Authors: De Baglion Laurent , Cedat Denis , Ould Pascal , Chitty Walter-John 
Published: November 2015

Because “safety” is still the key point in the Nuclear industry, more than in any others, the use of new materials or new manufacturing methods is really challenging. Among many characterizations required for a new steel grade or a new manufacturing process to be accepted and then introduced in a Nuclear design code, the fatigue properties must be determined with great care.
Nowadays, the consideration of the Pressurized Water Reactor (PWR) primary water environment effect on the Low Cycle Fatigue (LCF) behavior of Austenitic Stainless Steels (ASS’s) is an important issue for both Nuclear Power Plants (NPP) lifetime extensions and new builds as described in the NUREG/CR-6909 [1], [2].
This paper aims to present the LCF behaviors in air and in PWR water at 300°C of type 304L and 316L ASS’s manufactured by Powder Metallurgy coupled with Hot Isostatic Pressing process (PM/HIP) and to compare them with those observed on usual ASS nuclear grade products [3]-[6].
As already introduced in our previous paper [7] dedicated only to the PM/HIP 304L steel fatigue behavior, it appears that the microstructures, mechanical properties and LCF behaviors in air and in PWR water of both type 304L and 316L steels manufactured by PM/HIP process are better or at least similar to those observed on wrought ASS’s.
Comparison of the Stress Intensity Factor Influence Coefficients for Axial ID Surface Cracks in Cylinders of RSE-M and API 579-1
Authors: Le Delliou Patrick , Chapuliot Stéphane 
Published: November 2015

Analytical evaluation procedures for determining the acceptability of flaw detected during in-service inspection of nuclear power plant components are provided in Appendix 5.4 of the French RSE-M Code. Linear elastic fracture mechanics based evaluation procedures require calculation of the stress intensity factor (SIF). In Appendix 5.4 of the RSE-M Code, influence coefficients needed to compute the SIF are provided for a wide range of surface axial or circumferential flaws in cylinders, the through-wall stress field being represented by a cubic equation. On the other hand, Appendix C of API 579-1 FFS procedure provides also a very complete set of influence coefficients.
The paper presents the comparison of the influence coefficients from both documents, focused on axial ID semi-elliptical surface flaws in cylinders. The cylinder and crack geometries are represented by three ratios: Ri/t, a/t, and a/c, where Ri, t, a, and c are respectively the inner radius, the wall thickness, the crack depth and one-half of the crack length. The solutions for the coefficients G0 and G1 at the deepest point and at the surface point are investigated.
At the deepest point, the agreement between the solutions is good, the relative difference being lower than 2 %, except for the plate (Ri/t = ∞) at a/c = 0.125 and 0.0625 and a/t = 0.8 (around 5 %). At the surface point, the agreement between both solutions is not so good. At this point, the relative differences depend strongly on the a/c ratio, being larger for elongated cracks (with low a/c ratios). However, it must be recalled that the absolute values of the coefficients are low at the surface point for elongated cracks, and that for these cracks the critical point regarding the stress intensity factor is the deepest point.
RCC-MRX Edition 2015: Overview of Three Years of Developments
Authors: Pétesch C. , Lebarbé T. , de la Burgade F. , Bonne D. , Blat-Yrieix M. 
Published: November 2015

The 2015 edition of the RCC-MRx Code will be issued, by the end of the year, in French and English versions by AFCEN (Association Française pour les règles de Conception et de Construction des Matériels des Chaudières Electro-nucléaires). This Code set up rules applicable to research reactor components (coming from the RCC-MX 2008 developed in the context of the Jules Horowitz Reactor project), and to components operating at high temperature and to the Vacuum Vessel of ITER (coming from the RCC-MR 2007).
A significant work has been performed since 2012, first edition of the RCC-MRx, in order to improve the rules, to facilitate its use and understandability, and also to have a better fit with the feedbacks of the main projects (ASTRID, JHR, ITER).
This paper presents the technical evolutions in the 2015 edition and also the other initiatives led upstream (prenormative works) and downstream (publication of the rules background - criteria) of the publication of rules.
Hydrogen-Assisted Cracking Threshold of High-Strength Low-Alloy Steel
Authors: Yanagisawa Yusuke , Yoru Wada , Ohmi Toshihito , Yokobori A. Toshimitsu 
Published: November 2015

Threshold stress intensity factor Kih would be an appropriate index parameter for the cut-off limit in fatigue crack growth analysis in order to prevent hydrogen storage tanks from suffering brittle fractures at hydrogen stations. The Kih factors were evaluated using rising load and constant displacement tests conducted in high-pressure gaseous hydrogen. The following results were obtained:
1. Kih measured under rising load was less than Kih measured under constant displacement.
2. The difference of Kih increased as tensile strength decreased.
3. The difference of Kih may be attributed to the plastic wake of propagating cracks.
Hydrogen diffusion behavior at crack tips was also estimated by a finite difference method analysis.
Stress Intensity Factors for Complex-Cracked Pipes Based on Elastic Finite Element Analyses
Authors: Jeong Jae-Uk , Choi Jae-Boong , Huh Nam-Su , Kim Yun-Jae 
Published: November 2015

A complex crack is one of severe crack that can occur at the dissimilar metal weld of nuclear piping. A relevant fracture mechanics assessment for a pipe with a complex crack has become interested in structural integrity of nuclear piping. A stress intensity factor is not only an important parameter in the linear elastic fracture mechanics to predict the stress state at the crack tip, but also one of variables to calculate the J-integral in the elastic plastic fracture mechanics. The accurate calculation of stress intensity factor is required for integrity assessment of nuclear piping system based on Leak-Before-Break concept.
In the present paper, stress intensity factors of complex-cracked pipes were calculated by using detailed 3-dimensional finite element analysis. As loading conditions, global bending, axial tension and internal pressure were considered. Based on the present FE works, the values of shape factors for stress intensity factor of complex-cracked pipes are suggested according to a variables change of complex crack geometries and pipes size. Furthermore, the closed-form expressions based on correction factor are newly suggested as a function of geometric variables. These new solutions can be used to Leak-Before-Break evaluation for complex-cracked pipes in the step of elastic J calculation.
Effectiveness of Retightening in Maintaining Higher Residual Bolt Loads and Tightness of Bolted Flanged Connections
Authors: Kobayashi Takashi , Zenyoji Chihiro 
Published: November 2015

Bolt loads reduce significantly after tightening of bolted flanged connections in which expanded PTFE (Polytetrafluoroethylene) gaskets are used. Bolts are often retightened after a while to compensate for the reduction of bolt loads in practice. The visco-elastic characteristic of PTFE gaskets is the main cause for the phenomenon. The flexibility of the bolt-flange system also affects the phenomenon. However, effects of the retightening on the residual bolt loads and the tightness of flanged connections have not been clarified yet.
In this paper, an analytical model of a bolted flanged connection, in which the flanges, the bolts and the gasket are represented by spring constants, is proposed. The residual bolt forces and the deflection of the gasket were estimated based on the analytical model of the bolted flanged connection and a creep characteristic of the gasket. Thus, the relationship between gasket deflection and the tightness of the bolted flanged connection are clarified. Based on the analytical method, the effectiveness of retightening was discussed from the view points of the residual bolt load and the tightness.
Utilization of SPT Techniques for Evaluation of Changes in the Properties of the VVER-440 Reactor Pressure Vessel Steels After Their Irradiation in the Research and Power Reactors
Authors: Březina Martin , Petzová Jana , Kupča Ľudovít , Kapusňák Michal 
Published: November 2015

The paper describes the testing procedures and the basic results of the evaluation of the Small Punch Test (SPT) specimens after their irradiation in the Halden reactor in Norway. The SPT technique was used for estimation of basic mechanical properties as ultimate tensile strength and yield stress of the tested materials as well as the Fracture Appearance Transition Temperature (FATT).
The main aim of the work was to compare the SPT results obtained from the surveillance specimen programs implemented in the Slovak power reactors with the SPT results from the specimens irradiated in the research reactor in Halden. For the project there were chosen 3 types of steels used for construction of the reactor VVER 440/213 type in Bohunice NPPs in the Slovak Republic. The experimental materials were two bainitic steels — base metal and weld metal of the reactor pressure vessel wall and austenitic cladding of the reactor wall.
Two sets of SPT specimens together with mini-tensile specimens prepared from the experimental materials were irradiated in the Halden reactor. The samples were irradiated at 275°C to two fluence values which are equivalent to approximately of 4 and 6 campaigns in the power reactor. Obtained results are compared to up-to-date SPT results from the surveillance specimen program applied at Bohunice NPP in the Slovak Republic.