bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluation of Cr-Mo Steels Welds Produced by Gas Tungsten Arc Welding With High Silicon Solid Filler Rod to Omit Back Shielding – Second Report
Authors: Mori Koki , Takahashi Atsushi , Zhou Bin , Isono Shinya , Takauchi Hideaki 
Published: November 2024

Abstract
Where single-sided welding is applied to the fabrication and erection of piping, back shielding by inert gas and its maintenance for the first few layers are required for low alloy steels (LAS), stainless steels (SS) and nonferrous alloys to obtain good weldability and quality of welds.
However, installation and removal of back shielding isolations inside piping for the joint and the adjacent areas to be welded are sometimes impractical due to piping layout and construction sequence such as closure joints. And the unexpected remaining isolations sometimes become concerns for obstructing fluid flow or damaging piping components such as valves and rotating equipment during commissioning or after operation.
To solve the concerns, high silicon solid filler rod was experimented to 9Cr-1Mo steels welding by gas tungsten arc welding (GTAW) to omit back shielding, and positive results of the R&D were introduced in ASME PVP2023[1]. The same concept using high silicon solid filler rod for GTAW was expanded to welding for 5Cr-0.5Mo steels and properties of the welds were studied by comparison to the welds produced by different concentration of silicon in filler rods for the conventional GTAW with back shielding. This paper discusses and evaluates the potential of the GTAW with high silicon solid filler rod which can omit the inert gas back shielding for Cr-Mo steels and expected applications with the filler rod.
Aging Embrittlement of 1¼Cr–½Mo–Si and 1Cr–½Mo Steels
Authors: Sakata Mikihiro , Le Nevé Charles 
Published: November 2024

Abstract
Toughness degradation can be observed when 1¼Cr-½Mo-Si or 1Cr-½Mo steels are used at temperatures exceeding 500 °C (932 °F) for an extended period of time. However, research addressing this phenomenon is limited. Although temper embrittlement is one of the causes of toughness degradation of 1¼Cr-½Mo-Si and 1Cr-½Mo steels, embrittlement mechanisms have not yet been fully elucidated. This study comprises two parts. First, published information, experimental studies and the authors’ experiences on the aging embrittlement of 1¼Cr-½Mo-Si and 1Cr-½Mo steels were reviewed, focusing on both long-term operation and fabrication heat treatment (i.e., post-weld heat treatment). Second, Charpy impact toughness data obtained from vintage 1¼Cr-½Mo-Si and 1Cr-½Mo steels used at temperatures exceeding 500 °C (932 °F) for an extended period of time (up to approximately 45 years) were statistically analyzed. The majority of these steels were acquired from pressure vessels or piping in catalytic reforming or fluid catalytic cracking units that began operation in the 1970s or earlier. This study will help understand and predict the aging embrittlement of 1¼Cr-½Mo-Si and 1Cr-½Mo steels.
Third-Generation Test Facility for Strain-Controlled EAF
Authors: Seppänen Tommi , Arilahti Esko , Alhainen Jouni , Juvalainen Juho , Moilanen Pekka , Solin Jussi 
Published: November 2024

Abstract
Meeting the stringent requirements of strain-controlled testing standard ASTM E606 in simulated reactor coolant is challenging. Two earlier generations of bellows-based testing devices have proven direct strain control to be possible in deoxygenated PWR water at up to 350 °C and 150 bar. To meet future research demands, a third-generation device has been designed and is in the final phase of commissioning.
The first-generation miniature bellows loading device was designed as a prototype to prove the applicability of the technology for strain-controlled fatigue testing. All standard criteria for valid experimental results were not aimed to be met with the prototype, but the technology was successfully demonstrated. This encouraged later development of the second-generation “FaBello” devices. FaBello was designed to comply, as far as possible, with ASTM E 606. However, pneumatic load train and certain technology-related boundary conditions placed limits on the range of controllable test parameters.
With the emphasis on overcoming past limitations without straying from standard requirements, the third-generation “FaVite” devices were designed. Through the various improvements FaVite can be used to generate quantitative experimental results to assist in filling multiple environmentally-assisted fatigue knowledge gaps, as outlined in an EPRI report.
This paper gives a technical overview of the main challenges in conducting valid LCF experiments in simulated reactor coolant environment. Some proven solutions are introduced as well.
Continuum and Crystal Plasticity Coupled Finite Element Modelling to Explore Complex Loading Conditions
Authors: Allen Christopher , Coules Harry , Truman Christopher 
Published: November 2024

Abstract
Components in civil nuclear power plants are subject to high temperatures and pressures. Current methods to perform structural integrity assessments on said components are often overly conservative and cannot predict complex loading conditions. This is partially due to these approaches accounting for only macroscopic material behaviour and ignoring behaviour at a granular level. This has led to increased popularity in crystal plasticity finite element (CPFE) modelling due to its ability to simulate macroscopic and mesoscopic behaviour from a mechanistic perspective. A key factor in the accuracy of CPFE modelling is the boundary conditions applied. Periodic conditions allow the simulation of uniaxial stress states however, exploring more complex loading conditions is challenging.
This paper presents a multiscale methodology to apply complex loading conditions to a CPFE model. The material used in this study is Type 316H stainless steel. A macroscopic finite element model is produced of the desired component. At the region of interest, the resulting displacements generated are interpolated and applied to the surfaces of a CPFE model. To partially validate this approach, uniaxial and biaxial simulations have been performed.
The uniaxial simulations demonstrate that this approach captures uniaxial behaviour accurately at the macro- and meso-scale, as evidenced by comparisons with lattice plane deformation measured by diffraction techniques. The biaxial simulations match qualitatively well with experimental findings, but more quantitative comparisons must be drawn to exhibit the predictive capabilities.
Technical Basis for Fatigue Crack Growth Rules in Gaseous Hydrogen for ASME B31.12 Code Case 220 and for Revision of ASME VIII-3 Code Case 2938-1
Authors: San Marchi Chris , Ronevich Joseph A. , Bortot Paolo , Ortolani Matteo , Xu Kang , Rana Mahendra 
Published: November 2024

Abstract
Emerging hydrogen technologies span a diverse range of operating environments. High-pressure storage for mobility applications has become commonplace up to about 1,000 bar, whereas transmission of gaseous hydrogen can occur at hydrogen partial pressure of a few bar when blended into natural gas. In the former case, cascade storage is utilized to manage hydrogen-assisted fatigue and the Boiler and Pressure Vessel Code, Section VIII, Division 3 includes fatigue design curves for fracture mechanics design of hydrogen vessels at pressure of 1,030 bar (using a Paris Law formulation). Recent research on hydrogen-assisted fatigue crack growth has shown that a diverse range of ferritic steels show similar fatigue crack growth behavior in gaseous hydrogen environments, including low-carbon steels (e.g., pipeline steels) as well as quench and tempered Cr-Mo and Ni-Cr-Mo pressure vessel steels with tensile strength less than 915 MPa. However, measured fatigue crack growth is sensitive to hydrogen partial pressure and fatigue crack growth can be accelerated in hydrogen at pressure as low as 1 bar. The effect of hydrogen partial pressure from 1 to 1,000 bar can be quantified through a simple semi-empirical correction factor to the fatigue crack growth design curves. This paper documents the technical basis for the pressure-sensitive fatigue crack growth rules for gaseous hydrogen service in ASME B31.12 Code Case 220 and for revision of ASME VIII-3 Code Case 2938-1, including the range of applicability of these fatigue design curves in terms of environmental, materials and mechanics variables.
T-Slot Design and Fatigue Life Assessment of Coke Drum Skirt to Cone Knuckle Weld Joint
Authors: Scandroli Tony , Nassif Omar 
Published: November 2024

Abstract
Coke drums experience failures in through-wall cracking throughout their operating life, resulting from low cycle fatigue at the skirt to cone weld joint and keyhole slot ends. In some cases, drums built without keyholes have experienced 360° through-wall cracking within five years of operation. Keyholes are added to the skirt to mitigate low-cycle fatigue failures and extend the life of the drums. Typical designs terminate the slots with top and bottom holes, hence, keyhole slots. Once a skirt modification with keyhole slots and the coke drum is put into service, cracks at the top keyholes have been discovered as few as two years later. Depending on the crack size, there is little concern about these cracks breaching the pressure boundary of the drum. However, if unattended, they will continue to grow over time, and a breach of the coke drum’s pressure boundary is more likely. This paper presents T-Slots as an alternative to conventional keyhole design. An iterative methodology was used to compare changes in keyhole slots and T-Slots using finite element analysis (FEA) to optimize the geometry and placement. Several crotch radii, standard keyhole slot sizes, and T-slots are examined to find an optimum design with the most extended service life before fatigue crack initiation. T-slots were the most effective in extending the operating life of the Coke drum skirt to cone joints and slot ends.
Blast-Induced Failure Analysis of Liquid Ammonia Storage Tank
Authors: Slovenec Derek E. , Wood Joan , Kummari Seetha Ramudu , Prueter Phillip E. 
Published: November 2024

Abstract
Ammonium nitrate (AN) is a widely used compound in the agriculture and mining industries that, if improperly handled, poses a significant explosive hazard, as evidenced by the 2020 Port of Beirut explosion. In the wake of this event, the Australian government required failure analysis studies for all bulk AN storage. This paper details one such failure analysis study where bulk solid AN was stored at a mining facility that also featured a large, double-walled, refrigerated API 620 storage tank containing liquid ammonia. The goal of this study was to determine the quantity of solid AN that, if an explosion were to occur, could cause failure of the tank, potentially resulting in a significantly larger explosion. Nonlinear dynamic finite element analysis (FEA) was performed to simulate blast overpressure wave propagation and incidence upon the exterior tank wall and system response including contact between inner and outer tank walls. The tank was subjected to blast scenarios ranging from the equivalent of 77,000 lbsTNT up to 420,000 lbsTNT to study its behavior from essentially elastic response through effectively certain loss of containment. There is no industry standard or published code establishing failure criteria for a tank or pressure vessel subjected to an external explosion. Therefore, various sources were used to inform the criteria defining structural failure of the tank, including the United States Department of Defense Unified Facilities Criteria 3-340 (DOD UFC 3-340-02), ASME Boiler and Pressure Vessel Code Section VIII Division 3 (ASME VIII-3), and ASME VIII-2. Comparisons were made between these methods, and a range of AN quantities likely to cause failure of the tank is proposed. This study highlights the challenges of blast analysis, failure-level response simulation, and, ultimately, quantifying the consequence of cascading failure events.
Probabilistic Critical Initial Flaw Size Analysis in the Circumferential Welds of Layered Pressure Vessels
Authors: Kirby Matthew L. , Riha David S. , Cardinal Joseph W. , Hobbs Joel R. , Stoltz Brian C. 
Published: November 2024

Abstract
NASA operates as many as 300 non-code layered pressure vessels (LPVs) across their research and space flight centers. Many of these mission critical assets are operating beyond their expected service life, but replacement of these LPVs is cost prohibitive. Thus, NASA is interested in assessing fitness-for-service (FFS) and extending the life of these vessels when it is safe to do so. Since FFS of non-code LPVs comes with distinctive challenges, NASA has developed an alternate standard for FFS. Structural analysis under the alternative standard includes logic for performing probabilistic fracture mechanics assessments to estimate the cumulative distribution function (CDF) of critical flaw sizes for known and postulated flaws in key regions of the vessel. The resulting CDFs are predictive distributions that represent the current state of knowledge about the critical flaw size captured by models and data. This paper describes the probabilistic critical initial flaw size method employed by the alternative standard, and demonstrates its use to analyze a surface crack in the circumferential weld of a 9-layer vessel. It also discusses unique aspects of the probabilistic results and presents an approach for interpreting the probabilistic results in light of the deterministic critical initial flaw size solution.
Effect of Strength on Mechanical Properties of Linepipe Steel in High Pressure Hydrogen Environment
Authors: Imayama Hikaru , Izumi Daichi , Shimamura Junji , Nishihara Yoshihiro , Okano Hiroshi 
Published: November 2024

Abstract
In this paper, the fundamental material behavior and mechanical properties of linepipe steel in a high-pressure hydrogen environment were investigated. A fracture toughness test was carried out using the unloading compliance method (described in ASTM E1820) in 21-MPa hydrogen using bainitic steel of various strengths as the test material. Compared with the linepipe base material, namely American Petroleum Institute (API) grade X65, the fracture toughness of API grade X80 was inferior but that of API grade X70 was superior. The fatigue crack growth characteristics in hydrogen were inferior to those in air, with the effect of strength being small. The effect of strength on the hydrogen embrittlement of bainitic steel for linepipes was examined based on the change in fracture form after the test, presence of hydrogen trap sites, and hydrogen diffusion coefficient for the steel.
Transport of Large Nuclear Power Plant Components – New SCO-III Regulations and Mechanical Design Assessment
Authors: Komann Steffen , Wille Frank , Linnemann Konrad , Ramsay Jeff , Reiche Ingo 
Published: November 2024

Abstract
The decommissioning or refurbishment of nuclear facilities necessitates either the storage or disposal of large radioactive components such as steam generators, pressurizers, reactor pressure vessels and heads, and coolant pumps, to list the major contributors. These components or objects are large in size and mass, measuring up to approximately 6 meters in diameter, up to 20 meters in length, and weighing over 400 000 kg. In many situations, the components are transported off-site to a storage, disposal or recycling/treatment facility. Previously, many large objects had to be transported under special arrangement.
The latest 2018 edition of the International Atomic Energy Agency (IAEA) Regulations for the Safe Transport of Radioactive Material, No. SSR-6, incorporates regulations for the shipment of contaminated, but not activated large objects as a new category of surface contaminated object, SCO-III, based on the IAEA “performance package” concept.
This paper provides background and practical guidance on these regulations. Additionally, first experiences with SCO-III in the approval process are presented.
For SCO-III components a mechanical assessment regarding the tests specified in the transport regulations SSR-6 for demonstrating ability to withstand normal conditions of transport is required — a free drop of the package onto an unyielding target and a penetration test have to be investigated. Large components are unique objects; therefore, it is not possible to choose experimental testing as assessment method. The application of a complex numerical analysis for mechanical proof is necessary.
The assessment of the loads takes place based on local stress distributions.
The large nuclear components have typically been transported in an unpackaged manner, so that the external shell of the component provides the containment wall.
The paper will represent the methods, which are used for the evaluation of the mechanical integrity of the object for transport approval.
Proposal of Negative Stress Ratio R for Fatigue Crack Growth Rates of Austenitic Stainless Steels in Air for ASME Code Section XI Based on Trend in Experimental Data
Authors: Negyesi Martin , Yamaguchi Yoshihito , Hasegawa Kunio , Lacroix Valery , Morley Andrew 
Published: November 2024

Abstract
Fatigue crack growth rates da/dN for stainless steels in air environment are provided by the ASME Code Section XI. The fatigue crack growth rates are given by da/dN = CF(ΔK)n, where CF is the fatigue crack growth rate coefficient, n is the fatigue crack growth rate exponent and ΔK is the stress intensity factor range. The coefficient CF contains a temperature parameter ST, and a scaling parameter SR, which is a function of the stress ratio R. When the stress ratio R is positive from 0 to 1, the parameter SR increases with increasing the ratio R, and da/dN increases with increasing stress ratio R. When R is less than 0, SR = 1. Accordingly, fatigue crack growth rates under negative stress ratios are independent of stress ratios. This means that a cyclic stress state with a minimum that is compressive is considered to cause the same degree of crack growth as one with the same range but a zero minimum. However, from the results of literature survey, experimental data reveal that the fatigue crack growth rates decrease with decreasing R ratios below zero, i.e. negative stress ratios. The objective of this paper is to assess fatigue crack growth rates under such negative stress ratios for stainless steels in air environment. An equation determined from trends in experimental data surveyed in this study is proposed for negative R ratios to calculate the parameter SR for the ASME Code Section XI, Appendix Y.
Investigating the Influence of Analysis Parameters in Three-Dimensional Elasto-Plastic Finite Element Analysis of a Gate-Type Piping Support Structure
Authors: Takito Kiyotaka , Okuda Yukihiko , Nishida Akemi , Li Yinsheng 
Published: November 2024

Abstract
In probabilistic seismic risk assessment for nuclear power plants, developing a realistic response analysis method for the fragility assessment of piping systems considering input seismic motions exceeding the design assumptions is critical. Piping systems have complex three-dimensional shapes, and the arrangement and stiffness of the piping support structures significantly affect the response characteristics of the entire system. Therefore, developing a realistic response analysis method for piping systems and support structures is necessary. Therefore, in this study, to understand the difference in the degree of influence of the analytical parameters on the elasto-plastic deformation in the elasto-plastic analysis of piping support structures, the analytical parameters considered influencing the statics were estimated, and parameter studies were conducted. First, a three-dimensional finite element analysis model was constructed for the cyclic loading tests of a gate-type piping support structure, assuming large deformation. It was confirmed that the test and analysis results were correlated. A parameter study was then conducted using the developed model. Consequently, the difference in the degree of influence of the analysis parameters on the analysis results was understood as a large/small relationship, providing insight into the methodology for setting appropriate analysis parameters in the elasto-plastic analysis of piping support structures.
High Temperature Tensile and Creep Strain Measurement Using Image Edge Analysis
Authors: Davies Catrin Mair , Parker Chloe , De Andres Jorge , Liu Chen 
Published: November 2024

Abstract
An image-based technique has been developed to measure the reduction of diameter of a round bar sample. This process is based on imaging a round bar sample, and ensuring sufficient contrast is provided to detect the edge of the sample. The physically measured initial diameter of the sample is then converted to a number of pixels, and as a tensile of creep test is performed, the reduction in diameter of the sample is determined via pixel count. For isotropic materials this reduction in diameter can be converted to axial plastic and or creep strains. For high temperature tests, images are acquired through a windowed furnace. This image-based technique enables the true stress – true strain rate to be captured and the stresses in the neck to be determined, which is not possible with conventional axial extensometers. The image-based approach has been applied to uniaxial round bars of P91 steel at 600 °C under elastic-plastic tensile and creep loading conditions. The true stress-strain and true creep strain rates are presented during uniform deformation and in the necking region of the test.
De-Embrittlement of 1¼Cr–½Mo Steels
Authors: Suda Kazuki , Sakata Mikihiro 
Published: November 2024

Abstract
It is known that the toughness reduction of Cr-Mo steels owing to temper embrittlement can be alleviated by heat treatment above a certain temperature. This phenomenon (i.e., de-embrittlement) is, therefore, worth considering when there is a concern regarding brittle fracture in aging pressure equipment. In this study, vintage 1¼Cr-½Mo steels were taken from fluid catalytic cracking (FCC) reactors / orifice chambers and catalytic reforming reactors which started operation in 1970s. The steels were then heat-treated at various temperatures ranging between 530 °C and 720 °C (986 °F and 1,328 °F). Charpy impact toughness of as-received and heat-treated samples was investigated. The results showed that de-embrittlement could be achieved regardless of the impurity levels and operation periods. The result further indicated that the heat treatment at 570 °C (1,058 °F) was still effective as a de-embrittlement heat treatment for aging 1¼Cr-½Mo steels. This temperature is lower than the temperature noted in API RP571.