bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electromagnetic Lithium Ring Compression for Magnetized Target Fusion Application: Shell Buckling
Authors: Edalatfar Fatemeh , Santos Lemuel , Jayhooni Hashem , Dick Jean-Sebastien 
Published: November 2024

Abstract
Magnetized target fusion (MTF) relies on rapidly compressing magnetized plasma within a flux conserver to attain fusion conditions. Maintaining the smoothness and symmetry of the plasma-facing surface during compression is crucial, as any asymmetric deformation or buckling of the solid metal shell can disrupt magnetic confinement, reducing plasma temperature, and lifetime.
To establish the criteria for preventing buckling in solid ring implosions, we assess the effectiveness of the dynamic plastic flow buckling model. This assessment involves analyzing buckling phenomena in magnetically driven, imploding lithium rings. This investigation includes a total of 5 experiments with variations in collapse velocities, radius-to-thickness ratios, and initial ring temperatures. We capture and analyze the collapse trajectories and deformations of the rings during implosion using computer vision techniques. To establish material properties required for the theory, we utilize the Johnson-Cook model for the lithium ring with strain and strain rate extracted from the experiments. Using the extracted material properties and ring dimensions and employing the analytical model, we predict critical buckling velocities and dominant modes for each experimental scenario.
We observe qualitative agreement between the experiment and analytical model within measurement uncertainty, indicating the potential to define design, manufacturing, and quality requirements for larger-scale Magnetized Target Fusion experiments using solid shells to achieve fusion conditions.
Assessing a Hydroprocessing Reactor After a High Temperature Excursion
Authors: Batts Kevin , Penso Jorge , Hau Jorge , Dalal Mitul 
Published: November 2024

Abstract
A thick cold wall conventional 2.25Cr 1Mo steel with 347SS weld overlay and internal insulating refractory was affected during an external high temperature excursion in a resid hydrocracker unit. The reactor is part of a two-train unit with each train including two reactors. Reactor normal operating condition is 424–441 °C (795–825 °F) and 186 bar (2700 psig). A comprehensive metallurgical, non-destructive and fitness for service per API 579-1/ASME FFS-1 [1] assessment was completed before deciding to place the reactor in service. MTI publication No. 30: “Damage Assessment: Investigating Fires, Explosions, and Storm Damage in Chemical Plants” [2] was used as guidance as well.
The fitness for service assessments included shell out-of-roundness, leaning and distortion and local thin areas as consequence of scoop samples removal. An integrated computational materials engineering (ICME) approach was taken as part of the assessment for the future-service capabilities of a thick-walled steel pressure vessel that was damaged by overheating. Removal of scoop samples allowed for metallurgical characterization and mechanical property assessment. No repair was needed at the scoop sample locations. Indications of weld overlay disbonding were not reported. The different assessments supported the decision to place back the reactor in service with complementary monitoring plans. The reactor was returned to service and operated over two years, until the refinery was closed.
Development of the Buckling Evaluation Method for Large Scale Vessels in Fast Reactors Made of Grade 91 Steel and Austenitic Stainless Steel With Large Initial Imperfections
Authors: Okafuji Takashi , Miura Kazuhiro , Sago Hiromi , Murakami Hisatomo , Watakabe Tomoyoshi , Ando Masanori , Miyazaki Masashi 
Published: November 2024

Abstract
The current buckling design code of Class 1 vessels for fast reactors (FRs) power plant in Japan, “Design and Construction for Nuclear Power Plants, Division 2 Fast Reactors” by the Japan Society of Mechanical Engineers, focuses primarily on plastic buckling of austenitic steel vessel. For next-generation FRs, the higher-yield material, especially ASME Grade 91 steel, plans to be applied to the vessels such as steam generators in addition to austenitic steel. Seismic isolation system is also being devised in the next plant to meet the design seismic load in Japan.
To accommodate these conditions, the standard buckling strength equations were proposed in the previous study, which were modified by considering elastic-plastic buckling of vessel. The modified equations consisted of elastic-plastic axial compression, bending, shear buckling, and their interactions, as well as ASME/BPVC Code Case N-284, considering the reduction of buckling strength by cyclic larger vertical load with long-period lower horizontal load under the horizontal seismic isolation plant design. The applicability of the modified buckling equations was confirmed by a series of buckling tests and analyses under monotonic or cyclic axial compressive load accompanied with constant horizontal load in the previous studies. Thorough the experiment and simulation results, the conservatism of the modified equations has been confirmed to Grade 91 steel and austenitic stainless steel vessels with circumferential wrinkle shape corresponding to the elephant foot buckling mode as a significant initial imperfection, under the dominant cyclic axial compressive load accompanied with horizontal load.
In the most of tests and analyses in previous studies, the amplitude of the initial imperfections of vessels was less than or equal to half the wall thickness. However, depending on the fabrication method, the initial imperfection of the large scale vessels might be larger than that. Therefore, a correction factor was proposed to reduce the buckling strength calculated by the modified equations for large initial imperfections.
In this study, a series of elastic-plastic buckling analyses considering large displacement and large strain theories was conducted on Grade 91 steel and austenitic stainless steel vessels which have a wide range of dimensions, initial imperfection amplitude, and vertical/horizontal load ratio. The analysis results showed that the correction factor generally expressed a reduction tendency of buckling strength corresponding to initial imperfection amplitude, and the modified equations are applicable to the vessels in FRs power plant even for large initial imperfection amplitude which exceeds half the wall thickness.
Hydrogen Vessel Weld Porosity Stress Analysis Using CT Scan Data
Authors: Jiang Hao , Winder Drew , Armitage Douglas , Summerlot Nick 
Published: November 2024

Abstract
The Spallation Neutron Source (SNS) at the Oak Ridge National Laboratory produces the most intense, pulsed neutron beams in the world for various scientific research experiments and industrial development activities. The neutrons spalled from a mercury target are moderated and directed into instrument channels by the Inner Reflector Plug (IRP), which is designed for the purpose of moderating, reflecting, and shielding these neutrons. The SNS lower IRP is the bottom-most segment of the inner reflector plug components. The lower IRP is a complex structure consisting of an aluminum vessel, beryllium and stainless-steel reflectors, water and cryogenic hydrogen moderators, neutron poisons, and various channels for neutron transport. The lower IRP must be replaced regularly due to consumption of the neutron poisons and embrittlement of the structural materials from radiation.
The hydrogen moderators are constructed from 6061-T6 aluminum. Each hydrogen moderator has a vessel with concentric tubing for supply and return of 18K hydrogen. The hydrogen moderator vessel is welded to a connecting tube using gas tungsten arc welding (GTAW). Radiographic Testing (RT) of a moderator vessel during fabrication indicated porosity within the weld but did not define the location or shape of the porosity. For a better definition of the weld defects, the computed tomography (CT) scan technique was used to produce an accurate 3D image of the weld and weld defects. This paper will describe the procedure to incorporate the CT scan porosity data into the finite element model of a hydrogen moderator with a GTAW weld to determine fitness-for-service. The stress analysis was performed to evaluate the weld defects and to qualify the GTAW weld via the ASME BPVC design criteria.
Plastic Constraint Correction Factor X for Brittle Fracture in Ductile-Brittle Transition Temperature Region
Authors: Hojo Kiminobu , Hirota Takatoshi , Nagoshi Yasuto , Fukahori Takuya , Shimizu Kazuma , Shimodaira Masaki , Ogawa Takuya , Yashirodai Kenji , Ohata Mitsuru , Minami Fumiyoshi 
Published: November 2024

Abstract
In order to predict fracture behavior of a reactor vessel in the ductile-brittle transition temperature region under pressurized thermal shock, a plastic constraint correction factor χ is intended to be introduced into a Japan Welding Society standard. The WES standard will have two levels’ fracture assessments, Level I, a simplified assessment, and Level II, a detailed assessment. The plastic constraint correction factor χ for Level I will be provided by formulas with the parameters, yield strength σy, strength ratio Ry defined by the ratio of yield strength σy to ultimate strength σB, and the Weibull shape factor m with some application limitations. Further, the plastic correction factor χ should depend on geometry factors, such as flaw depth a, flaw aspect ratio a/c, and structure’s thickness. In this paper, sensitivity analyses were performed for thickness, flaw depth, flaw aspect ratio, strength ratio, and the Weibull shape parameter m to apply the plastic constraint correction factor χ for Level I assessment to various reactor vessels. Also, temperature dependency of the Weibull parameters, m and σu was investigated. Based on these results, the formulas of χ were revised and the application limitations for the parameters were expanded. This paper will be one of technical basis for the WES standard.
Non-Linear Buckling Analysis of Thin-Walled Cylindrical Shell Having Large Openings
Authors: Rafique Muhammad Raheel 
Published: November 2024

Abstract
It was required to introduce multiple large openings (windows) in an internal liner shell of a vessel to facilitate the inspection and repair of refractory behind the liner on the main shell. As a part of repair procedure, the castable refractory behind the liner required dry-out at around 520°C. Analysis was performed based on API 579-1/ASME FFS-1; Annex 2D/ASME Sec VIII Div.2; Protection Against Collapse From Buckling, in order to evaluate if the liner shell with large openings could withstand its own weight and high dry-out temperature without any additional support(s). For finite element analysis (FEA), the 3D Model was generated by considering the actual size and orientation of the windows as required at site. At first, Linear Static Structural Analysis was performed by applying gravity load, and then the solution of the linear static analysis was used to perform Eigenvalue buckling analysis to obtain different mode shapes. Selecting appropriate mode shape(s) with suitable load multiplier and scale factor, non-linear Elastic-Plastic Analysis was performed by considering plastic behavior of the material and gravity (self-weight) as well as thermal (dry-out temperature around 520°C) loads. The solution converged, and the protection against collapse from buckling was ensured. Subsequently, the repair activities and thermal dry-out of refractory were performed successfully, without any impact on the liner shell.
Pressure Vessel Design With Strain Rate Sensitive Materials: Lessons From a Refractory Material
Authors: Hajy Akbary Farideh , Hoeijmakers Maarten , Kapadia Rahul S. , Peters Daniel T. , Richardson Ian , Koestenbauer Harald 
Published: November 2024

Abstract
In pressure vessel design, understanding material toughness is critical. This challenge becomes more pronounced when designing vessels using strain rate sensitive materials, due to their low toughness determined from high strain rate tests, such as impact tests. This paper is focused on the design of a pressure vessel made from nominally pure molybdenum, with toughness properties sensitive to the strain rate, due (in part) to its body-centred cubic (BCC) structure. The material is manufactured from a powder subjected to hot isostatic pressing. The applied approach presented here not only describes some of the factors involved in characterizing materials for a pressure vessel design, but also presents a general approach that should be applicable to other strain rate sensitive materials. In this paper we consider the measurement of fracture toughness and other material properties at different temperatures, including the criteria for specimen design, and determining test parameters based on the intended application. We also consider the information necessary for pressure vessel lifetime assessment, based on a fracture mechanics approach.
Proposed Compression Testing Validation for Large ASME B16.20 Spiral Wound Gaskets
Authors: Bao Tommie , Hugo C. Von 
Published: November 2024

Abstract
ASME spiral wound gaskets are widely used in many different industries. It is one of the most common gasket types and readily available in the market. During construction of spiral wound gaskets, the manufacturer is responsible for determining the filler thickness and density of windings. To validate those selections, the gaskets must pass a leakage and compression criteria set by ASME.
For this paper, we will focus on the compression test as required in B16.20 and using criterion values supplied in section SW-2.2 Construction. Testing of smaller gaskets is a relatively straightforward process, however, this is not feasible for larger NPS and pressure class gaskets. The primary obstacle is the available force from a compression test machine. Common compression machines have limited upper load. Another constraint is the diameter of the compression machine’s plates. These limitations make testing for large gaskets impractical, especially when dealing with gaskets for ASME B16.47 Series A and B flanges.
In this paper we are proposing a method to understand the compression performance of larger gaskets by testing them in segments, where the gasket is positioned partially under the compression machine and applied forces are based on the applicable gasket contact area.
Experimental and Analytical Verification of ASME Section III, Division 5 Creep-Fatigue Design Rules
Authors: Wang Yanli , Jetter Robert , Sham Ting-Leung 
Published: November 2024

Abstract
The continuous advancement of structural materials and the growing demands for more reliable and economical structural components in high-temperature reactor applications have necessitated the development of comprehensive design methodologies and design rules. Mechanical degradation of structural components at elevated temperatures subjected to cyclic deformation is controlled by the creep-fatigue damage. Over the past few decades, diligent research efforts have been dedicated to refining the development of elevated temperature design rules in the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (BPVC), Section III, Division 5 and to develop conservative design rules that can effectively guard against the risk of creep-fatigue failure.
In ASME Section III, Division 5, for a design to pass the creep-fatigue acceptance criteria, creep damage and fatigue damage are evaluated separately, and these damages must not violate the bi-linear creep-fatigue interaction diagram, i.e., the so-called D-diagram. The creep-fatigue damage evaluation procedure assumes that the effects of the actual cyclic loading sequence can be bounded by assuming that the individual loading cycles are uniformly distributed throughout the component design life. In this study, creep-fatigue experiments with variable amplitudes and loading sequencies were designed and performed on Alloy 617 at high temperatures. The results were analyzed to evaluate the loading history effect on creep-fatigue damage accumulation and to verify the assumptions for the creep-fatigue evaluation design rules.
A Simplified Approach Used to Evaluate Equipment Nozzles for Offshore Cyclic Wave Conditions
Authors: Kirkpatrick Kenneth , Millet Barry , Mosher Bryan , Lu James , Miller George 
Published: November 2024

Abstract
The dynamic nature of wave loading in the offshore marine environment creates many fatigue design challenges. Process equipment (pressure vessels, pumps, heat exchangers, etc.) has been mounted on marine facilities and ships since the dawn of powered ships. In the last century more and more sophisticated process units have been ship or platform mounted. This began with the offshore exploration, production of oil and gas in the 1930’s and the advent of nuclear propulsion for ships and submarines in the 1950’s. The nuclear propulsion industry has addressed the fatigue issues since the beginning. In the oil and gas industry, offshore marine facilities and ships, in particular, which includes barges, fixed leg platform, semi-submersibles, tension leg platforms, SPARS, jack-up rigs and FPSO, fatigue on process equipment may have been mostly ignored. Today the software used to evaluate marine facilities and ships for dynamic sea states produces fatigue design data (in terms of accelerations and frequencies) that can be used in the evaluation of process equipment. When evaluating pressure vessels, each vessel contains many nozzles, each nozzle is subjected to multiple loading conditions, and it may be a very large task to evaluate each nozzle for the applied cyclic conditions. This paper will present a simplified stress-based method used to evaluate the process nozzles for accumulative fatigue damage. A simple example will be provided showing how to develop the allowable stress and how it is applied. It is possible that this method may also be expanded to cover components other than nozzles.
Optimizing Preload in a HPHT API 6BX Flange When Subject to Thermal Loading
Authors: Owen Ruth , Ward Peter , Farnell Richard , Christie Andrew 
Published: November 2024

Abstract
This paper uses finite element models of an API flange to consider the suitability of the maximum bolt preload permitted by API 17D, 67% of the bolt’s material yield stress [1]. The flange was reviewed under ambient temperature, and under a large thermal gradient. Pressure and external tension were also considered. The performance of the flange under these conditions was then used to inform the selection of an optimal preload, to maximize the load capacity.
Investigation of Shape Behaviour of Opening on Cylindrical Shell As Per ASME SEC.VIII DIV.1: A Comparative Study of Various Codes of Construction
Authors: Pathre Sujay S. , Gopalakrishnan Shyam , Qadeer Mohammad Abdul , Mathkar Ameya 
Published: November 2024

Abstract
Owing to various practical requirements, pressure vessels are frequently designed with openings of diverse shapes, sizes, and placements. According to the requirements outlined in ASME Sec. VIII Div. 1 Code [1], specifically in section UG-36 (a), it is advisable that openings in the cylindrical or conical sections of vessels, as well as in formed heads, should ideally assume circular, elliptical, or obround shapes. When an elliptical or obround opening has a long dimension which exceeds twice the short dimension, it becomes necessary to add extra reinforcement to mitigate the risk of excessive distortion due to twisting moments. However, it is important to note that the ASME Sec. VIII Div. 1 Code does not provide rules for conducting such assessments and instead directs designers to use section U-2(g).
The primary objective of this paper is to investigate the behavior of these openings situated on the cylindrical surface of vessels, focusing on scenarios where the ratio of the long dimension to the short dimension falls in the proximity of 2.0. This study involved a comprehensive examination of various International Codes, including ASME SEC.VIII DIV.2 [2], PD5500 [3], EN 13445 [4] and AD 2000-Merkblatt [6], to gain insights into their respective requirements. Furthermore, finite element analysis (FEA) was conducted to evaluate the resultant stresses, thereby corroborating the findings of the various International Codes.
Non-Destructive Examination Limits for Fracture Mechanics Design of High Pressure High Temperature Subsea Equipment
Authors: Daflon Thiago , Stewart Barry , Lee Sam , Parayitham Sashidhar 
Published: November 2024

Abstract
The design and operation of High Pressure / High Temperature (HP/HT) equipment in the oil and gas industry using API 17TR8 drives requirements for fracture mechanics fatigue verifications. The inputs used as part of the fracture mechanics assessment require to be defined in order to ensure the integrity of the assumptions and results. Such assessments assume the HP/HT product may include an initial flaw that is equal to the size of the minimum indication detectable by the defined Non-destructive Examination (NDE) technique used as part of the part quality requirements. This size of this initial flaw can have a large impact on the overall fatigue life of the product and can influence the operating conditions of the subsea operator. Therefore, the smaller the initial crack size that is detectable the longer the subsea operating window and the harder the conditions that can be tolerated.
Historically, in the subsea oil and gas industry, API 6A limits on detectable flaws have been assumed but these limits do not define the Probability of Detection (POD) or confidence level of the NDE techniques used. This paper outlines a test methodology for deriving the POD and confidence level of NDE techniques based on the use EDM notches in sample plates. Results of the testing show the ability of the NDE techniques used in the test to detect initial EDM notches that align with the API 6A limits of 1/16″ long flaws with a POD of 90% and with a confidence level of 80%. The impact of using this size of initial flaw on the fracture mechanics assessment of a HP/HT product is outlined with significant improvements in fatigue life achieved.
Coke Drum Skirt Life-Cycle Management
Authors: Seijas Antonio , Berry Alex 
Published: November 2024

Abstract
Delayed coking is a form of thermal cracking used for processing “bottom barrel” residuum in a refinery delayed coking unit (DCU). Coke drums, which are key components of the process, are subject to thermal cyclic and aggressive operating conditions and have a finite life. A safe and reliable operation before replacement requires special considerations to manage the key aspects defining the coke drum life-cycle. The skirt to vessel connection has been identified as one of the critical locations limiting the coke drum life; the skirt-to-vessel weld is vulnerable to fatigue cracking, while the skirt itself is vulnerable to bulging and key holes cracking. In this paper, key aspects of coke drum life-cycle management will be discussed, covering the useful life of coke drum skirts from “cradle” to “grave.” Important aspects such as supplemental requirements for skirt design and fabrication, specialized in-service inspection, on-line monitoring, engineering assessment, repairs and replacements will be covered in detail. This paper includes a short literature review of common skirt designs and damage mechanisms of greatest concern with consideration given to fabrication of skirts for both new coke drums and skirt retrofitting projects. Five case studies are reviewed in detail including: the analysis of the skirt configuration for a new pair of coke drums; two coke drum set skirt retrofitting projects; two skirt repair events in two separate coke drum sets. The paper will include closing remarks and recommendations to help improve the management of skirts for these complex and critical pressure vessels.