bluuebunny/crossref_metadata_2025_split huggingface dataset:
Piping Seismic Design Method by ASME CC N-900
Authors: Shibukuwa Kenichi , Wen Jie , Funasaki Kenji 
Published: November 2024

Abstract
In seismic isolation structures for nuclear power plants, it has been reported that conventional seismic design methods cannot be applied to the seismic design of crossover piping against building isolation boundaries, which are supported by numerous supports, due to problems such as the overlap between the large relative displacement of the anchor section and the response amplification of the pipes. One solution to this problem is a seismic evaluation method based on elastic-plastic analysis of piping. ASME published a code case that provides strain-based acceptance criteria for seismic evaluation of piping system for Level D service level in 2019, but it is still not fully used in actual seismic design work because specific evaluation procedures and key design data such as true fracture strain are not developed in ASME CC N-900[1]. Therefore, this paper provides with the strain base criteria, technical background and seismic evaluation procedures by using ASME CC N-900[1]. Also, in order to explain the applicability of the “design evaluation procedure for piping” proposed to actual design, this paper reports a results of sample evaluation to “piping design of small-diameter piping in buildings that can be seismically designed according to ASME Section III NCD-3650” instead of crossover piping against seismic isolated boundaries and confirms the basic characteristics of the piping design evaluation procedure using ASME CC N-900.
Ultrasonic Phased Array Linear-Nonlinear Fusion Imaging Method of Microcracks in Pressure Equipment
Authors: Cheng Jingwei , Fan Zhichao , Chen Xuedong , Chen Wei , Wang Zhe , Bu Yangguang 
Published: November 2024

Abstract
Crack is one of the most significant defects that easily occurs during the use of pressure equipment. The growth of microcracks is seen to be at an exponential rate. Therefore, it is very necessary to detect microcracks within the equipment through non-destructive testing (NDT) promptly to avoid their rapid propagation from giving rise to safety risks during the operation of equipment. As a manifestation of early damage to materials, microcracks are prone to inability of detections and misjudgment of detections by employing conventional detection methods. Acoustic nonlinearity has been shown to deliver some sensitivity to early damage from the materials, so it can be analyzed with the implementation of nonlinear ultrasonic detection techniques. Compared with conventional ultrasonic detection methods, phased array technology utilizes multichannel transmission and reception, delivering wider detection coverage without repositioning the probe. Therefore, this technique is advantageous over other NDT methods for microdefect detection. This paper demonstrates the high sensitivity of nonlinear ultrasonic imaging metrics to the crack tip by combining them with the linear imaging method (total focusing method), thereby achieving morphological reconstruction and quantitative evaluation of buried microcracks within the structure. Experimental results show that the linear-nonlinear fusion imaging method can effectively characterize the defects.
Effect of Hydrogen Pressure on Hydrogen Embrittlement Behavior of 23Cr2Ni4MoV High Strength Steel
Authors: Yang Hao , Chen Xuedong , Fan Zhichao , Zhou Yu 
Published: November 2024

Abstract
In this paper, effects of gaseous hydrogen pressure on the mechanical properties and fracture morphology of the 23Cr2Ni4MoV steel were analyzed by modified slow strain rate tensile (MSSRT) test and scanning electron microscope (SEM). The results show that the plasticity of 23Cr2Ni4MoV is significantly influenced in hydrogen environment with respect to that in nitrogen environment, rather than the yield strength and ultimate tensile strength. The elongation (EL) and the reduction in area (RA) are degraded by 79% and 68% in 35 MPa gaseous hydrogen with respect to the results in 35 MPa gaseous nitrogen. The crack initiates at the surface of the sample in the hydrogen, and the initiation depths influenced by hydrogen are 100 μm, 300 μm, and 700 μm in 1 MPa, 10 MPa and 35 MPa hydrogen environment, respectively. In the nitrogen environment, the microstructure of the crack-initiated region is dimple; while in the hydrogen environment, it is cleavage and rock-sugar like. In addition, in the hydrogen environment, circumferential cracks appear at the surfaces near the fracture of 23Cr2Ni4MoV steel.
Embrittlement of 347H Stainless Steel Welds in 538 °C (1000 °F) Service
Authors: Hau Jorge , Dalal Mitul , Penso Jorge 
Published: November 2024

Abstract
A metallurgical evaluation was conducted involving 347H stainless steel welds removed from a resid hydrocracking unit hot hydrogen pipe system, after 5 and 15 years of service. The welds were found to have embrittled. The absorbed energy of Charpy tests was as low as 18 J (13 ft-lb). Tensile test ductility was as low as 7–9% elongation. The creep ductility of these welds was found to be rather low. The elongation to stress rupture varied from 0.5 to 0.9%. The Ω factor varied from 382 to 548. However, creep strength was as good as new 347H stainless steel base metal. Average magnetic ferrite number FN measurements indicated values of 1.4 to 2.1, on cross sections, and of 1.6 to 2.9 on the OD. All these welds were stabilize-heat treated at 900 °C (1650 ± 25°F) for a minimum of 4 hours when installed and again, to stress relief after welding. This reduced the FN. Solution annealing at 1066 °C (1950 °F) followed by water quenching fully restored Charpy absorbed energy values, tensile test ductility, significantly reduced the yield strength but caused no changes in the tensile strength. This solution annealing treatment increased creep strength but did not restore creep ductility at all. Creep brittle welds are more prone to form crack than creep ductile material, at high stressed locations, which are typically notch-like geometric configurations or defects. Thus, the high creep brittleness found at these 347H welds is a concern, which is why it was investigated.
Development of a Program Based on Re-Meshing for Natural Crack Growth of Multiple Cracks
Authors: Lee Gi-Bum , Hong Chan-Gi , Yoon Seok-Jun , Huh Nam-Su , Park Sung-Hoon 
Published: November 2024

Abstract
Nuclear power plant facilities undergo periodic in-service inspections for structural integrity assessment. During these inspections, when multiple cracks are detected, the stress distribution and fracture mechanics parameters at the crack tips can be significantly influenced by the adjacent cracks. Therefore, to accurately conduct multiple crack evaluation and crack growth, it is essential to consider such crack interactions. Existing code and standards (ASME Section XI, API 579, and BS7910) provide guidelines for the evaluation and coalescence produce for multiple cracks. However, these conventional procedures may assume conservative evaluations, such as merging two close elliptical cracks into a single larger ellipse. In this study, a program based on adaptive meshing through finite element analysis was developed which includes generating crack tip meshes suitable for coalescing multiple cracks. After crack coalescence, criteria for crack tip relaxation considering the spider-web mesh were applied, and the coalescence distance criterion from ASME Section XI was employed. Fatigue crack growth was performed using both the coalescence criteria applied in the program and those from ASME Section XI, and the crack growth results were compared. This analysis aimed to evaluate the impact of the coalescence assumptions from ASME Section XI on crack assessment.
State-Dependent Seismic Fragility Functions for Bolted Flange Joints on Special-Risk Industrial Substructures
Authors: Nardin Chiara , Bursi Oreste S. , Broccardo Marco , Marelli Stefano 
Published: November 2024

Abstract
Seismic vulnerability assessment of industrial plants and process equipment has gained attention lately. However, the complexity of the problem and its modelling, combined with a general scarcity of available data on industrial systems, contributed to limiting or developing risk assessment methods based on extremely simplified models. On these premises, a new methodology that combines limited data from finite element FE models with cutting-edge machine learning techniques is developed to generate state-dependent fragility functions for critical components mounted on archetypical industrial substructure modules. Specifically, referring to the classical forward uncertainty quantification scheme, a physics-informed FE model, calibrated on the results of a comprehensive shake table test campaign of a real-scale industrial braced-frame BF steel substructure, is considered. Time histories of seismic event sequences generated by a site-based ground motion model compose the input provided to the FE model. The uncertainty is then propagated through Monte Carlo analysis on inexpensive-to-run polynomial chaos expansion (PCE) metamodels set for each starting damage level condition measure. As a result, empirical state-dependent fragilities are evaluated, assuming the lognormal distribution.
Prediction of Compressive Residual Stresses According to Ultrasonic Nanocrystal Surface Modification Process Variables of Alloy 600
Authors: Seok Tae-Hyeon , Choi Ju-Won , Huh Nam-Su 
Published: November 2024

Abstract
Primary water stress corrosion cracking (PWSCC) has been reported in Alloy 600 components. PWSCC occurs due to a combination of high tensile residual stress, corrosive environment, and susceptible material. Prevention of PWSCC primarily involves mitigating tensile residual stresses. One of the peening techniques, ultrasonic nanocrystal surface modification (UNSM), applies a static load and high frequency ultrasonic vibrations of 20 kHz to the strike pin, generating high compressive residual stresses on the surface. Predicting the variation in compressive residual stress according to process variables is essential for analyzing the prevention of PWSCC. Numerous studies have been conducted to predict compressive residual stresses according to process variables, but research on Alloy 600 is insufficient. The finite element analysis methodology is compared to experimental results. Static load and amplitude are considered as variables. The analysis results are quantitatively analyzed, categorizing into surface residual stress, maximum residual stress, and effective depth. As the static load and amplitude increase, the compressive residual stress becomes larger and affects deeper. Amplitude has a greater influence on magnitude of surface residual stresses than static load.
Ultrasonic Examination of Welds in Cast Austenitic Stainless Steel PWR Reactor Coolant System Piping Welds
Authors: Hayden John , Van Velsor Jason 
Published: November 2024

Abstract
ASME Section XI Class 1 RCS piping system welds fabricated using CASS materials pose serious and well-understood challenges to their effective ultrasonic examination. For decades, utilities and regulators have struggled with the administrative and financial burdens of Relief Requests, which were, and are still, based on the inability to perform meaningful volumetric examinations of welds in CASS components. Many years of futility and frustration may have also fostered the belief that the technology that would allow the effective and meaningful examination of CASS materials would never be achievable. This is no longer the case.
The failure mechanism for CASS material occurs through the loss of fracture toughness due to thermal aging embrittlement. The susceptibility of CASS material to thermal aging embrittlement is strongly affected by several factors, primary of which are system operating time and temperature, the casting method used during component manufacture and molybdenum and ferrite content. In addition to the existing ASME Section XI requirements for the examination of welds in CASS materials, the susceptibility to thermal aging embrittlement drives the requirement for additional examinations (including ultrasonic examinations) as directed by several NRC-published NUREGs required for plant license renewal.
This paper also describes the laboratory examinations of CASS pipe weld specimens that has resulted in an effective ultrasonic examination technique for the detection, length and through-wall sizing of flaws in CASS piping welds, which plays a very important part for both currently required Inservice Inspections (ISI) and for plant license renewal Aging Management Programs.
Seismic Sliding in Storage Tanks: An In-Depth Analysis and Design Insights
Authors: Manjrekar Vivek , Stokes Neville , Choi Junho 
Published: November 2024

Abstract
The response of storage tanks to earthquake forces has been the subject of extensive research worldwide, resulting in a wealth of data that provides guidance for designing tank components capable of withstanding earthquake loads. This includes determining the necessary freeboard to account for sloshing wave heights, calculating base shear forces, and assessing overturning moments, among other considerations. However, there is a notable gap in the available information pertaining to a crucial aspect of tank behavior during seismic events: their ability to resist sliding. The absence of comprehensive experimental data or research findings in this area has led tank design standards like API 620[1,4] to adopt a conservative approach, considering sliding resistance solely through friction between the tank and the subgrade and imposing higher safety factors. While these safety precautions are undoubtedly essential, they can sometimes result in impractical tank configurations, particularly for large-capacity tanks.
To address this significant knowledge gap, this study focuses on investigating the force required to initiate sliding and the post-sliding impact on tank components, especially anchor straps. Additionally, the research delves into evaluating resistance to lateral loads using the shear friction method by leveraging the shear capacity of mechanical anchorage. To achieve this, nonlinear finite element analysis is utilized using nonlinear geometry and elastic-plastic material properties.
Microstructure and Mechanical Performance of X120 Linepipe Steel in High-Pressure Hydrogen Gas
Authors: Wang Yiyu , Feng Zhili , Wang Yanli , Ronevich Joseph , Agnani Milan , San Marchi Chris 
Published: November 2024

Abstract
Hydrogen-induced degradation, especially hydrogen-assisted fatigue, and fracture, must be carefully considered to maintain reliability and structural integrity of steel pipelines in gaseous hydrogen service. Additionally, the susceptibility of steels to hydrogen is well documented to be sensitive to the strength of the steel. Therefore, high strength pipeline steels with yield strength greater than 600 MPa, such as X100 and X120, must be evaluated to assess their susceptibility to hydrogen embrittlement. In this work, microstructure and mechanical properties, including the fatigue crack growth rate and fracture toughness in high-pressure hydrogen gas at a pressure of 1000 bar (105 MPa), of an as-received X120 steel were experimentally investigated. The results show the fatigue crack growth rates in gaseous hydrogen of this X120 steel follow the ASME design curves for hydrogen from the Boiler and Pressure Vessel Code Section VIII, Section 3 Code Case 2938-1. The fracture resistance in 1000 bar hydrogen gas is 43 MPa·m1/2, which is higher than approximately 30 MPa·m1/2 reported for Cr-Mo and Ni-Cr-Mo pressure vessel steels with the similar tensile strength level (approximately 950 MPa). Multi-scale metallurgical analyses were conducted to characterize the underlying microstructural features contributing to the higher fracture toughness of X120 compared to the Cr-Mo and Ni-Cr-Mo steels. The characterization shows a fine bainitic microstructure (grain size: 1 μm) and fewer carbides, characteristics created by the thermo-mechanically controlled processing (TMCP) and a lower carbon content, respectively. These features likely provide a higher fracture resistance in gaseous hydrogen compared to the traditional tempered martensitic microstructure of pressure vessel steels with greater carbon contents. A fractography analysis on the tested X120 specimens was also conducted to further reveal its fracture characteristics under high-pressure hydrogen gas. Both fatigue and fracture surfaces exhibit mainly quasi-cleavage cracks. Secondary cracks propagated in a mixed intergranular and transgranular mode. The fracture surface is much coarser and has deeper secondary cracks than that in the fatigue region.
Load Carrying Capacities of Small-Diameter Pipe Bends Under Internal Pressure: Analytical and Computational Predicitions
Authors: Robinson Nicholas , Wang Xin , Wasiluk Bogdan 
Published: November 2024

Abstract
The performance and embedded conservatism of common modeling approaches used for predicting load carrying capacities were evaluated for small-diameter pipe bends typically found in CANDU reactors. Comprehensive analyses were conducted using both an analytical approach and detailed finite element modelling with commercial code ABAQUS. Small diameter pipe bends, with and without local wall thinning, under loading by internal pressure were investigated. The adopted modelling approach incorporated variability in pipe bend geometry and the characterization of material properties.
The results obtained indicate that load carrying capacities of small-diameter pipe bends, either with or without local wall thinning but characterized by uniform wall thickness and single parameter material strength are conservatively predicted with analytical models in principle based on the limit load approach. However, detailed finite element modelling is needed for obtaining more accurate predictions of plastic instability pressure for pipe bends with local wall thinning.
The reported investigation provides technical insights into the modelling approaches presently used for predicting load carrying capacities of small-diameter pipe bends under internal pressure loading; in addition, it has explored embedded conservatism while recognizing the existence of involved uncertainties. The results obtained emphasize the importance of detailed characterization of pipe bend thickness and material strength in such engineering predictions.
This work has been performed under Canadian Nuclear Safety Commission (CNSC) Research and Support (R&S) project R765.1. The insights obtained may be used to further assess embedded conservatism in fit for service evaluations of CANDU outlet feeders experiencing wall thinning due to Flow Accelerated Corrosion (FAC). In addition, supplementary information informs the activities related to lowering the minimum required thickness below 75% of a straight pipe thickness by Article NB-3640 of Section III of the ASME B&PV Code for design pressure.
Comparison Between Fatigue and Fracture Behavior of Pipeline Steels in Pure and Blended Hydrogen at Different Pressures
Authors: Agnani Milan , Ronevich Joseph A. , San Marchi Chris 
Published: November 2024

Abstract
Existing natural gas (NG) pipeline infrastructure can be used to transport gaseous hydrogen (GH2) or blends of NG and hydrogen as low carbon alternatives to NG. Pipeline steels exhibit accelerated fatigue crack growth rates and reduced fracture resistance in the presence of GH2. The hydrogen-assisted fatigue crack growth (HAFCG) rates and hydrogen assisted fracture (HAF) resistance for pipeline steels depend on the hydrogen gas pressure. This study aims to correlate and compare the HAFCG rates of pipeline steels tested in two different gaseous environments at different pressures; high-purity hydrogen (99.9999 % H2) and a blend of nitrogen with 3% hydrogen gas (N2+3%H2). K-controlled FCG tests were performed using compact tension (CT) samples extracted from a vintage X52 (installed in 1962) and a modern X70 (2021) pipeline steel in the different gaseous environments. Subsequently, monotonic fracture tests were performed in the GH2 environment. The HAFCG rates increased with increasing GH2 pressure for both steels, in the ΔK range explored in this study. Nearly identical HAFCG rates were observed for the steels tested in different environments with equivalent fugacity (34.5 bar pure GH2 and 731 bar Blend with 3%H2). The fracture resistance of pipeline steels was significantly reduced in the presence of GH2, even at pressure as low as 1 bar. The reduction in HAF resistance tends to saturate with increasing GH2 pressure. While the fracture resistance of modern steel is substantially higher than vintage steel in air, in high pressure GH2, the HAF resistance is comparable. Similar HAF resistance values were obtained for the respective steels in the pure and blended GH2 environment with similar fugacity. This study confirms that fugacity parameter can be used to correlate HAFCG and HAF behavior of different hydrogen blends. The fracture surface features of the pipeline steels, tested in the different environments are compared to rationalize the observed behavior in GH2.
In-Situ and Ex-Situ Studies on the Morphology Changes of Polymer Pipeline Materials for Use in Hydrogen Gas Environments
Authors: Simmons Kevin , Ko Seunghyun , Kuang Wenbin , Qiao Yao , Shin Yongsoon , Han Kee Sung , Menon Nalini 
Published: November 2024

Abstract
The US natural gas infrastructure is a national asset that could be used to deliver hydrogen and hydrogen blends of natural gas as a pathway to reduce carbon emissions. The distribution system comprises nearly 50% plastic pipe composed of medium- and high-density polyethylene materials (MDPE and HDPE). While these materials perform adequately for natural gas, research on their hydrogen compatibility is essential to understand if any immediMDPEate and long-term risks are associated with hydrogen addition. The Blended Gas CRADA, a HyBlend project, has established a comprehensive test method for evaluating MDPE and HDPE of various plastic resin compositions of pipeline material in pure hydrogen and 20% hydrogen/80% methane blends. Both in-situ and ex-situ measurements were performed to capture hydrogen-induced changes in the polyethylene material’s crystalline, amorphous, and interphase regions.
We investigated MDPE and HDPE pipeline materials made from different polymer resin systems to evaluate the effects of hydrogen gas. The materials were characterized by their density, diffusion coefficient, free volume ratio, and degree of crystallinity. Various advanced characterization methods, including in-situ high-pressure NMR, ex-situ XRD, ex-situ DSC, and ex-situ TDA, were used to analyze the effects of changes in crystalline, amorphous, and interphase regions due to gas exposure. Time-dependent post-decompression quasi-static tensile tests were conducted to explore the effects of gas exposure time on the mechanical behavior of the pipe materials.
This work will highlight the time sensitivities during and after gas exposure. The correlation between gas-induced polyethylene morphology changes and the associated material performance will be addressed for the intended applications. These studies will show that polyethylene resin composition and material exposure are important factors when considering whether hydrogen gas affects pipeline materials positively or negatively.