bluuebunny/crossref_metadata_2025_split huggingface dataset:
Statistical Methods and Database Splitting for HCF Data Analysis
Authors: Blatman Géraud , Le Roux Jean-Christophe , Wallin Kim , Solin Jussi , Métais Thomas , Karabaki Ertugrul , Mayinger Wolfgang 
Published: December 2016

Fatigue curves are receiving nowadays an increased level of attention in the wake of experimental campaigns showing that the original ASME III mean air curve, also known as the Langer curve [1], does not represent accurately part of the recently obtained laboratory data.
EDF, VTT and E.ON have been working towards a relevant fatigue assessment strategy. The three organizations recently exchanged HCF databases, providing a common benchmark to test and compare the various analysis methods. Following the 2014 PVP paper [2], several statistical approaches are being investigated. A special focus is given to methods able to properly account for run-out data points, which do not have the same statistical significance as failed data points.
Besides, it has to be noted that only a limited number of material grades are used in NPP primary loop components and in each case, the material batches are identified and specified in detail. Therefore, a more accurate and relevant fatigue assessment might be obtained by splitting large datasets that generally mix various testing conditions and material grades. A comparison is made between a “mixed” approach and a “separated” one, in which the fatigue assessment is performed successively for two or more subsets, e.g. associated with two testing temperature ranges and/or steel grades. Both “mixed” and “separated” strategies are applied to the EDF and the E.ON databases containing fatigue data in different temperatures for non-stabilized and stabilized austenitic stainless steels. The resulting data scatters are compared and the significance of these statistical approaches to fatigue assessment is discussed.
Development of a Quick and Easy-to-Install Strain Measurement Tool for Both Bending and Torsional Piping Stress Assessment
Authors: Takahama Tsunemichi , Nishimura Kazuma , Ninomiya Seiichiro , Matsumoto Yoshihiro , Harada Yutaka 
Published: December 2016

To assess the stresses on small-bore piping, we have developed a new tool that can be easily installed on a piping surface without adhesive bonding and that measures strains on piping quickly and accurately. This tool, which we call a “strain gauge holder,” is patented in Japan.
As the tool can contain four strain gauge rosettes, with each rosette comprising three elements, the longitudinal strains and sheer strains can be measured synchronously at any four points precisely 90 degrees apart, with one point in each quadrant.
By mockup testing, we confirmed that the measured bending and torsional strains by the holder were almost equivalent to the measured strains by the bonded gauges with adhesive, and that the holder made it possible to synchronously measure all of the strains resulting from the moment of force acting in three axes on the piping by measuring the bending and torsional strains in each quadrant.
The strain gauge holder is expected to significantly reduce the pre- and post-working time required for strain measurement and stress assessment of piping in real plants.
Use of the Extended Finite Element Method in the Assessment of Delayed Hydride Cracking
Authors: Booth Martin , Martin Michael 
Published: December 2016

Zirconium alloys, as used in water-cooled nuclear reactors, are susceptible to a time-dependent failure mechanism known as Delayed Hydride Cracking, or DHC. Corrosion of zirconium alloy in the presence of water generates hydrogen that subsequently diffuses through the metallic structure in response to concentration, temperature and hydrostatic stress gradients. As such, regions of increased hydrogen concentration develop at stress concentrating features, leading to zirconium hydride precipitation. Regions containing zirconium hydride are brittle and prone to failure if plant transient loads are sufficient.
This paper demonstrates the application of the Extended Finite Element Method, or XFEM, to the assessment of the DHC susceptibility of stress concentrating features, typical of those considered in the structural integrity assessment of heavy water pressure tube reactors. The method enables the calculation of a DHC threshold load. This paper builds on the process-zone approach that is currently used to provide the industry-standard DHC assessment of zirconium alloy pressure tubes and also recent developments that have extended the application of the process-zone approach to arbitrary geometries by the use of finite element cohesive-zone analysis. In the standard cohesive-zone approach, regions of cohesive elements are situated in discrete locations where the formation of zirconium hydride is anticipated. In contrast, the use of XFEM based cohesive formulations removes the requirement to define cohesive zones a priori, thereby allowing the assessment of geometries in which the location of hydride material is not known.
Dimensional Accommodation of Bolt Coating and its Impact on Bolt/Thread Loading Capability
Authors: Cheta Ayman , Bett B. J. (John) 
Published: December 2016

Coated bolting has been widely used on flanged joints of pressure vessels and piping whenever there is a potential for atmospheric corrosion. The applied bolt coating has to be dimensionally accommodated, typically by over tapping the nut or less frequently, under sizing the bolt threads. A recently published technical paper by MacMoy, Ian [7], alleged that this practice is not in compliance with relevant industry standards and potentially compromises the sealing integrity of the flange joint. MacMoy’s paper recommended that any coating that requires over tapping in order to apply a coating’s optimal thickness should be avoided.
In this paper, the authors investigated relevant industry practices, and performed proof testing of some sample bolt sizes. The outcome of this investigation and the details and results of the proof-testing are shared in this paper.
An Approach to Modification of Compact Tension J-R Curves for Analysis of Surface Cracked Pipe Stability
Authors: Olson Richard 
Published: December 2016

It is well known that J-R curves from C(T) specimens do not have the correct constraint for surface cracked (SC) pipes. More appropriately, fracture toughness for surface cracked pipes is better characterized by two-parameter models where toughness is not a single value like J, but rather is a curve that defines a critical locus of fracture toughness and constraint values. Unfortunately, for the vast majority of situations, toughness property data for pipe fracture analyses using elastic-plastic fracture mechanics (EPFM) J-estimation scheme techniques to assess the load carrying capacity of the cracked pipe section, consist only of C(T) specimen J-R curves. The alternatives, when analyzing a surface crack, are to simply use the C(T) data and live with the consequences or else perform the analysis using some sort of “correction” applied to the C(T) specimen data to get better predictions of surface crack stability.
This paper examines the feasibility of using a correction to a C(T) specimen J-R curve to yield better predictions of the load carrying capacity of surface cracked pipe. The analyses discussed herein are constrained by: a) The availability and limitations of analytical models of the relevant phenomenon, and b) The availability of experimental pipe fracture data to test hypotheses about the form of a “correction”. Within these constraints, an initial estimate of a “correction” has been developed and is tested against some surface crack pipe experimental data.
License Renewal Experience in the U.S.: Continue to Seek Long Term Operation or Shutdown?
Authors: Young Garry G. 
Published: December 2016

As of January 2016, there were 99 operating nuclear units in the U.S. and the NRC had renewed the operating licenses for 81 of those nuclear units allowing for up to 60 years of safe operation (83 renewed licenses had been issued, but 2 of those units are now shutdown). In addition, the NRC has license renewal applications under review for 11 more units and 5 units have announced plans to submit applications in the next few years. This brings the total of renewed licenses and plans for renewal to almost 100% of the 99 operating units in the U.S. At the end of 2015, there were about 40 nuclear units that had operated for more than 40 years and most of those units are eligible to seek a second license renewal for up to 80 years of operation. [1]
Unfortunately, in the past few years, 5 nuclear units have been prematurely shutdown and 3 additional units with licenses to operate for 60 years are scheduled to be prematurely shutdown between 2016 and 2019 for economic reasons. However, the majority of the nuclear plant owners are keeping the option open for long term operation beyond 60 years. NRC and the U.S. nuclear industry have made significant progress in preparing the way for a second round of license renewal applications. For example, the NRC published draft regulatory guidance on the second (or subsequent) license renewal process in December 2015. This paper presents the status of the efforts underway for possible applications for second license renewals for up to 80 years of operation and the issues that may result in additional premature plant shutdowns in the U.S.
Application of the Modified Ritchie–Knott–Rice Criterion to Predict Fracture of Miniaturized Charpy Type SE(B) Specimens From Full Sized Specimens
Authors: Yamaguchi Teruhiro , Higashino Yuma , Meshii Toshiyuki 
Published: December 2016

This paper introduces our experience of using miniaturized Charpy type SE(B) specimen in obtaining fracture toughness Jc of a material in the ductile to brittle transition temperature (DBTT) region. 0.55% carbon steel JIS S55C, whose tensile to yield stress ratio σTS/σYS was equal to 1.8 was chosen as a material to simulate a degraded (embrittled) material in the DBTT region.
Focus was placed on whether the modified Ritchie–Knott–Rice (RKR) failure criterion which predicts the onset of cleavage fracture when the crack opening stress measured at 4 times the crack-tip opening displacement σ22d exceeds this σ22c can be applied to miniaturized specimen that does not meet the ASTM E1921 requirement of M = (W-a)σYS/Jc ≥ 30. In concrete, the points 1) whether it could predict whether cleavage fracture will occur or not and 2) whether the σ22c in the case cleavage occurs is identical with that of full sized specimens, were focused. Charpy type SE(B) specimens of Width W × thickness B of 2 × 2 mm, 3 × 3 mm and 10 × 10 mm, whose M were predicted to be smaller than 30, were chosen as miniaturized specimens and 25 × 25 mm were chosen as full sized specimen. Results showed that the modified RKR criterion could appropriately predict cleavage fracture naturally for 25 × 25 mm specimens and 10 × 10 mm specimens, though M < 30 for this type specimen. The modified RKR criterion could also predict that cleavage fracture will not occur for 2 × 2 mm specimens. σ22c obtained from 25 × 25 and 10 × 10 mm specimens showed small difference, indicating that Jc obtained from 10 × 10 mm specimens can be used to transfer Jc obtained by 25 × 25 mm specimens.
Propagating ASME PCC-1 Appendix A Compliance
Authors: Barnard Jason M. 
Published: December 2016

In November 2013 the revised ASME PCC-1 “Guidelines for Pressure Boundary Bolted Joint Assembly” were published including Appendix A, “Training and Qualification of Bolted Joint Assembly Personnel.” This Appendix outlines a training, examination and qualification system for ensuring a consistent level of knowledge and experience for bolting assemblers and specialists working on bolted flange joint assemblies. The ultimate objective is a mobile workforce capable of bolting ASME plant with a minimum performance standard safely and with no subsequent leaks.
Major operators and contractors involved in oil and gas, petrochemical and power generation, or any industry that uses bolted flange joint assemblies, can benefit from PCC-1. Benefit recognition has begun with operators now specifying PCC-1 compliance in their procedures and bid packages.
However, nearly three years after the introduction of Appendix A the number of Qualifying Organizations approved to deliver the program and individuals qualified via these programs remains stubbornly small in comparison with other programs and insufficient to meet the future safety demands of the industry or the objective of PCC-1 and Appendix A.
This technical paper reviews key elements of Appendix A, compares Appendix A with other international qualifications and suggests recommendations intended to increase recognition and compliance with these guidelines. The recommendations and expected benefits follow from an extensive review of work by other organizations and published data concerned to reduce recorded leaks from bolted joints, including:
a) Implementation lessons learned from a Qualifying Organization and Review Organization.
b) Current international qualifications and the differing routes to achieve each qualification including:
1) ASME PCC-1 Appendix A Training and Qualification of Bolted Joint Assembly Personnel.
2) European standard EN1591-4 Qualification of personnel competency in the assembly of the bolted connections of critical service pressurized systems.
3) Engineering Construction Industry Training Board (ECITB) Mechanical Joint Integrity (MJI) technical training standards and Step Change in Safety Mechanical Joint Integrity Route to Competence Guidance
4) Additional country specific qualifications
c) Program effectiveness study of the Engineering Construction Industry Training Board (ECITB) Mechanical Joint Integrity (MJI) program and the Step Change in Safety Hydrocarbon Release (HCR) model set up to achieve leak reduction in the UK North Sea sector.
Finally, the paper will conclude with outlining the benefits to be gained globally through standardization of international qualification programs to enable true portability including:
a) The need to increase the number of auditable Qualifying Organizations able to deliver the program, qualify individuals and engage operator/contractors in the process.
b) Importance of effective communication and summary of the guidelines.
Cyclic Response of Enhanced Bolted Flange Joints for Piping Systems
Authors: La Salandra Vincenzo , Di Filippo Rocco , Bursi Oreste S. , Paolacci Fabrizio , Alessandri Silvia 
Published: December 2016

Bolted Flange Joints (BFJs) represent the most common and critical components used nearly in all industrial piping systems, including Oil & Gas plants. Owing to their strategic importance and heavy consequences both to the environment and human lives due to both damage and leakage, BFJs are considered very important in industrial plant design. Therefore, their behaviour becomes critical also under seismic actions.
Along this line, in the first part of this paper the experimental test campaign performed on enhanced bolted flange joints subject to both monotonic and cyclic loading is presented and discussed. Then, specific values of both stiffness and strength with reference to leakage are estimated. Successively, a reliable model capable of predicting the leakage force for a generic BFJ, including the interaction between the axial and shear load, is proposed and validated; in particular, both actual and previous full scale experimental data were involved in the validation. As a result, the values predicted by the model agree well with those obtained by the experiments. This model is also adopted to predict leakage stiffness values for thick flanges. Overall, the proposed analytical model can represent a promising tool for the leakage prediction of BFJs in complex piping systems.
Analysis of Pressure Relief Valve Dynamics During Opening
Authors: Bossard John , Reich Alton , DiMeo Alex 
Published: December 2016

In nuclear power plants power actuated pressure relief valves serve several purposes. They act as safety valves and open automatically in response to unusually high pressures in the primary system. They also act as power operated valves and are used to relieve steam in response to automatic or manually initiated control signals. These valves are required to lift completely over a short duration from the time that they receive an actuation signal, or the system pressure exceeds the set point. This short lift time results in the valve disk moving at high velocities, and can result in high impact forces on the piston and stem when the valve fully opens.
To quantitatively evaluate the dynamic performance of the Target Rocket Pressure Relief Valve, an analysis effort was undertaken which would accommodate both the fluid dynamic features of the valve operation, as well as the kinematic characteristics of the valve, during pressure relief valve operation.
To execute the analysis, the Generalized Fluid System Simulation Program (GFSSP) was used. GFSSP is a network flow solver CFD code developed by NASA that has the ability to analyze transient, multi-phase flows, and conjugate heat transfer, along with the inclusion of custom user subroutines developed by the user which can accommodate other simulation requirements.
In this paper we present the GFSSP model developed, and the computed results that could be compared with corresponding parameters as measured from experimental testing for the pressure relief valve. Adjustments to GFSSP input parameters allow the anchoring of the GFSSP valve model to test data. This makes it possible to use the GFSSP model as a predictive tool for understanding valve dynamics, as well as evaluating proposed pressure relief valve modifications for performance improvements.
Direct Strain-Controlled Variable Strain Rate Low Cycle Fatigue Testing in Simulated PWR Water
Authors: Seppänen Tommi , Alhainen Jouni , Arilahti Esko , Solin Jussi 
Published: December 2016

A tailored-for-purpose environmental fatigue testing facility was previously developed to perform direct strain-controlled tests on stainless steel in simulated PWR water. Strain in specimen mid-section is generated by the use of pneumatic bellows, and eddy current measurement is used as a feedback signal. The procedure conforms with the ASTM E 606 practice for low cycle fatigue, giving results which are directly compatible with the major NPP design codes.
Past studies were compiled in the NUREG/CR-6909 report and environmental reduction factors Fen were proposed to account for fatigue life reduction in hot water as compared to a reference value in air. This database exclusively contained non-stabilized stainless steels, mainly tested under stroke control. The applicability of the stainless steel Fen factor for stabilized alloys was already challenged in past papers (PVP2013-97500, PVP2014-28465). The results presented in this paper follow the same overall trend of lower experimental values (4.12–11.46) compared to those expected according to the NUREG report (9.49–10.37).
In this paper results of a dual strain rate test programme on niobium stabilized AISI 347 type stainless steel are presented and discussed in the context of the NUREG/CR-6909 Fen methodology. Special attention is paid to the effect of strain signal on fatigue life, which according to current prediction methods does not affect the value of Fen.
Design and Assessment for Creep-Fatigue and Creep-Fatigue Crack Growth
Authors: Ainsworth Robert A. 
Published: December 2016

Creep-fatigue assessments require inputs for both creep damage and fatigue damage. Then these damage terms are combined using some form of interaction diagram to enable estimation of the creep-fatigue life. Similarly, creep-fatigue crack growth assessments need separate calculations of creep crack growth, fatigue crack growth and again possibly some allowance for interaction in order to obtain the total crack growth. A consequence of these approaches is that uncertainties in creep calculations, uncertainties in fatigue calculations and uncertainties in the form of interaction all lead to significant uncertainties in the overall lifetime or crack growth assessment.
This paper first briefly describes how creep-fatigue and creep-fatigue crack growth assessments are performed using the UK R5 procedure and contrasts the methods with those in other codes. Then, the paper presents the guidance in R5 on addressing the many uncertainties in these assessments and discusses the use of probabilistic methods in order to avoid over-conservative lifetime and crack growth estimates.
On a Design Acceptability of 90° Elbow According to Pipe Length at Elevated Temperature Condition
Authors: Jeong Seong-Yun , Won Min-Gu , Choi Jae-Boong , Huh Nam-Su , Oh Young-Jin 
Published: December 2016

Sodium-cooled Fast Reactor, SFR is promising candidate of Generation-IV reactor. SFR is operated at high temperature and low pressure. For reducing high thermal stress, thin-walled components and structures are employed for SFR. However, thins-walled components are vulnerable to seismic damage[1].
In this paper, the structural integrity assessment are performed to investigate the effect of piping length on creep-fatigue and seismic damage at elevated temperature. L-shaped elbow is considered for piping design and finite element analyses are conducted to calculate creep-fatigue and seismic damage. The evaluation of creep fatigue damage is carried out according to the elevated temperature design codes of ASME B&PV Sec. III Subsec. NH-3200[2]. Seismic damage are evaluated based ASME B&PV Sec. III Subsec. NB-3600[3] and ASME B&PV Sec. III Div.5 HBB-3200[4]. From the results of creep-fatigue and seismic damage, limit length of piping is determined.
Analytical Comparison Between Separate Reinforcement Nozzle and Integral Reinforcement Nozzle Behaviors Under Cyclic Loading
Authors: Mohamed Bassel Y. , Eid Tamer I. 
Published: December 2016

ASME code explicitly addresses design for fatigue due to pressure or temperature cycles. Protection against fatigue failure due to cyclic external mechanical loads (e.g. piping loads) is not tackled in depth.
This paper provides a less-tedious yet fit-for-purpose approach to evaluate the effect of cyclic external mechanical loads as well as the pressure fluctuations — as a result of piping slug flow — on nozzles fatigue life. The evaluation compares between two types of nozzles construction (configuration); separate reinforcement nozzle and readily radiographed (lip type) integrally reinforced nozzle. Within the analysis, a unity fatigue damage ratio or exceeding the ratcheting allowable limits was selected as the indication for the inadequacy of the reinforcement configuration.
COMPRESS® FEA software results comprehensively predict that the separate reinforcement nozzles can’t withstand the imposed cyclic loads since the accumulated fatigue damage are greater than 1 (one) implying that the nozzle will experience fatigue failure before the end of its life time. COMPRESS® FEA results were examined at four locations, namely “shell next to nozzle”, “nozzle next to shell”, “nozzle thickness transition” and “shell away from nozzle”. The maximum stress of the four locations was always at “shell next to nozzle”.
These results have been verified against SOLIDWORKS® simulation FEA results.
The results show that the separate reinforcement nozzle construction, although adequate for static loadings, has less fatigue life compared to the integral reinforcement nozzle construction. Moreover, progressive distortion of the non-integral (separate) reinforcement connection is predicted showing that the mating members may become loose at the end of each complete operating cycle which could eventually cause disengagement. Additionally, the results support ASME 2004, VIII-2 para. 5-112 recommendations in prohibiting fillet welds in joints of category D for components subject to fatigue service.
The paper concludes the advantage of integral reinforced readily radiographed nozzle construction in protection against fatigue failure and ratcheting and also provides a roadmap for simplified fatigue analysis using commercially available software.