bluuebunny/crossref_metadata_2025 huggingface dataset:
Parametric Numerical Assessment of an Aerojet General Nucleonics Reactor Against Postulated Fire Conditions
Authors: Jyung Jae-Min , Chang Yoon-Suk
Published: November 2023

As a part of periodic safety review of nuclear power plants, it is required to ensure fire protection of major facilities and structures in accordance with consolidated international and national legislations. However, most of studies have been focused on huge commercial reactors and lack of information on small research or educational reactors. The objectives of this research are to implement fire hazard analyses of an aerojet general nucleonics (AGN) reactor by using two numerical softwares and to address effect of relevant parameters. Firstly, a remarkable oil fire scenario was assumed by taking into account characteristics of compartments with various fire areas, ventilation conditions, duration time, and so on. Then, thermal integrity of reactor room was evaluated by computational fluid dynamics simulation and structural integrity of the simplified AGN reactor module was checked by systematic finite element simulation. Further, contributions of each parameter and interaction among parameters were quantified, from which not only temperature histories but also von-Mises stress distributions were calculated. As results, it was proven that all the maximum stress values were lower than the corresponding allowable criterion to sustain integrity of the reactor module. Also, the duration time was determined as the most influential parameter and interaction effect between fire area and duration time were significant.
Ultra-Thick 9% Nickel Plates for Cryogenic Pressurized Equipments
Authors: Pillot Sylvain , Milek Jean-Christophe , Higelin Anne , Zuazo Ian , Loukachenko Natalia
Published: November 2023

9%Ni (as per ASME SA553 type I) is the reference material for the fabrication of large LNG flat bottom above ground storage tanks servicing at −163°C/−260F and industry has then a long experience with that alloy. Considering the case of pressurized applications, the situation is largely different as only few examples of using 9%Ni can be found. AISI 304L austenitic stainless steel is in that case the material of choice, despite its low strength.

On one hand, usual applications in LNG business as well as new low temperature applications linked to the Global Energy Transition could benefit of high performances coming with that alloy. Its high strength and allowable stresses — in comparison to ones on 304L — permit to significantly reduce the wall thickness of pressure vessels while keeping an excellent level of toughness and hence of safety.

But on the other hand, experience with thick sections is very scarce and pressurized equipments fabrication require significantly thicker products than ones encountered in low pressure above ground flat bottom storage tanks. Consequently, demonstration of the industrial feasibility of such equipments needed to be done.

The present paper aims at summarizing recent developments made to produce ultra-thick plates (up to 100mm/4inches thick) and properties achieved on such thick products. Base materials as well as welded joints have been extensively studied, in various thermal states able to replicate all industrial configurations required by customers involved in the fabrication of large cryogenic pressurized vessels. Materials properties after PWHT were measured, as some pressure vessel construction codes may require such treatments after welding or forming operations, depending on design conditions and on considered product thickness. Finally, heterogenous welds between 9%Ni and 304L austenitic stainless steel have been tested with the aim of enabling the use of conventional pressure vessel sub-components (such as nozzles, piping, flanges) with 9%Ni pressure vessels.

Performances down to −196°C/−320F have been addressed by the various tests made during the study. All results achieved are satisfactory and it is demonstrated to be safe to use 9%Ni for the fabrication of large pressure vessels.
A Simplified Yet Effective Approach for Calculating Permissible Loads on Bracket Supports Attached to Cylindrical Shells
Authors: Manjrekar Vivek , Stokes Neville , Choi Junho
Published: November 2023

The analysis of bracket loads on tanks and vessels from pipe supports and other attachments is a frequently encountered problem for design engineers. A careful evaluation of stresses due to discontinuity between the bracket attachment and shell is required. One of the most commonly used methods for evaluation of external loads on cylindrical shells is WRC Bulletin 107/537, however this method is limited to maximum radius-to-thickness ratio (R/T) of 300. For thin-walled shells, the R/T ratio can be much higher.

In this research work, the stresses in cylindrical shell at bracket attachment are studied using finite element method. Cylinders with varying R/T ratios and brackets with different configurations are considered. Based on the study results, a simplified method is proposed for calculating the allowable loads on bracket attached to cylindrical shell of tanks and vessels. The non-dimensional coefficients are provided to determine the limiting forces and moments in each direction. These coefficients take into consideration the hoop stresses due to product head and internal pressure. Correction factor to account for excess thickness in shell plate is included. For checking the combined effects of forces and moments in all directions, interaction equations are provided. Lastly, sample example is presented to demonstrate the application of the proposed method.
A Study of Stress Relaxation Cracking Mechanism in a 347H Steel Pipe-Shoe Weldment After Five-Year Service
Authors: Wang Yiyu , Yang Yi , Gao Yanfei , Penso Jorge , Feng Zhili
Published: November 2023

347H stainless steel has been widely used for piping, furnace tubes, pressure vessels and other pressure boundary components in oil refining plants because of its excellent high-temperature strength and high oxidation and sulfidation resistance. However, cracking failures in 347H steel weldments could occasionally occur and significantly shorten lifetimes of those welded heater components. In this work, a comprehensive metallurgical analysis was conducted on a cracked 347H steel pipe-shoe weldment after only about 5-year service at a petroleum refinery. Premature cracking mechanisms of this pipe-shoe weld were studied in detail by correlating multiple factors, including service conditions, weld configuration, chemical compositions, and microstructure degradations. Microstructural characteristics of different regions in the weld, including fusion zone, heat affected zone, and base metal, were examined using multi-scale microscopic techniques. The results show the cracks initiated at the fusion boundary in the weld toe and propagated towards the heat affected zone and base metal in an intergranular manner. The cracks grew via connecting grain boundary cavities formed during service. Insufficient precipitation strengthening from M23C6, and MX assisted nucleation and growth of cavities along grain boundaries was observed. Ferrite formation along grain boundary induced a high localized strain along grain boundaries, which also favored crack propagation. Due the thermal gradient during service, the microstructure degradation (cavities) along the pipe wall thickness direction was not uniform, the region near the outer diameter has more cavities than that of the inner diameter wall. It is suspected that the high stresses in the weld toe region caused by the deviation from component’s original design and rotational forces on the weld resulting from the weld configuration, were the main external driving force responsible for this observed early failure. A combination of stress relaxation cracking, thermal stresses, and microstructure degradation was likely the main culprit for this premature cracking issue.
Pipeline Steel Tabular DA/DN Curves With Validations, & Potential Hydrogen Transport Application
Authors: Harter James A. , Lamborn Lyndon
Published: November 2023

Fitting da/dN data with closed-form equations can introduce unwanted error into a crack growth model. Using a tabular look-up approach which remains strictly data-driven has historically found utility in aerospace, and could become equally useful in fitting emerging da/dN results for hydrogen-charged pipeline steels. The objectives of this paper are to document the process for tabular datafitting, illustrate its functionality for pipeline steels, present validation work completed, and illustrate a sample application to pipe steels in a diffusible hydrogen environment.

The tabular crack growth rate model is based on the Walker equation applied on a point-by-point basis at selected crack growth rates. This paper will review the historical basis for the method, provide details of the development and considerations for pipeline steel curves, discuss important modelling issues, and validation work completed to date on in-service onshore pipeline incidents.

The tabular da/dN method applied to hydrogen-charged pipe steels is compared and contrasted to a proposed piecewise equation-based method. Life comparisons for the two methods are conducted for some actual gas and liquid pipeline operating cycling severities. Sensivity to ancillary growth influences, such as superposition of residual stress fields and time dependency are illustrated. A unified stress corrosion crack life analysis with both mechanical and time dependent growth in a hydrogen-charged pipe steel is illustrated. The utility of tabular full range da/dN curves in the aerospace community is summarized to compare and contrast potential utility in the pipeline industry.
Modeling a Spent Nuclear Fuel Cask Seismic Test
Authors: Klymyshyn Nicholas , Kadooka Kevin , Fitzpatrick James , Spitz Casey
Published: November 2023

The US Department of Energy Spent Fuel and Waste Science and Technology (SFWST) program is planning to conduct a series of full-scale shake table tests to simulate hypothetical earthquake conditions and record the response of surrogate spent nuclear fuel (SNF) assemblies in a canister dry storage system mockup. The shake table motions will represent a range of hypothetical earthquake conditions at hypothetical locations in the continental US to generally define the range of mechanical loads that SNF can be expected to experience during extended dry storage periods. The earthquake conditions will represent seismic hazards in the 2,000-to-20,000-year return period range.

The test will use instrumented pressurized water reactor (PWR) fuel assemblies with surrogate mass inside the fuel rods instead of radioactive fuel pellets. Dummy assemblies with similar mass and dimensions to actual fuel assemblies will occupy the rest of the fuel assembly locations in a SNF canister that holds 32 fuel assemblies. The canister will be located inside a mockup vertical concrete cask (VCC). Instrumentation will record the motion of the major components of the complex dynamic system, and strain gauges will be used to record the cladding strain at selected locations. Preparations for the test require modeling predictions to identify the range of response of the system and to help select specific earthquake ground motion cases to be simulated on the shake table from a larger set of potential cases.

This paper describes the pretest nonlinear finite element modeling efforts that have been completed to date, including cask system level modeling and fuel assembly modeling in LS-DYNA. The cask system level models are critical for anticipating sliding or tipping of an unanchored cask during the test. The fuel assembly model is needed to estimate the range of cladding strain response and fuel assembly structural response to be expected during the test and cladding strain measurements will be key metrics for model validation and the development of modeling best practices after the test is concluded.
Investigation on Buckling Instability Behavior Mechanism of Rubber Balloon of Bladder Accumulator of Cavity Pressure
Authors: Ni Tianyv , Wang Bo , Duan Chenghong
Published: November 2023

Bladder accumulator is a common buffer element in hydraulic oil circuits, it would abnormally deform during decompression on occasion, resulting in a liquid-trapped phenomenon. In order to investigate the mechanism of this unusual phenomenon, firstly, an experimental study focused on the deformation state of the rubber balloon of bladder accumulator was conducted. Secondly, according to the actual working load conditions of the bladde accumulator, a self-compiled VDLOAD user subroutine was used for loading, and the nonlinear post-buckling analysis of the rubber balloon was performed by displacement perturbation method based on the buckling mode. Finally, influences of the pressure in the balloon cavity on the post-buckling deformation of the rubber balloon were explored. The results show that the oil-trapped deformation of the rubber balloon experiment is in good agreement with the post-buckling analyzed deformation state. It is concluded that the oil-trapped phenomenon of the bladde accumulator is due to the buckling instability deformation of three pits on the premise of the uniform hydraulic distribution. In addition, the gas pressure in the balloon cavity affects the post-buckling deformation mode of the rubber balloon. Within the design pressure range, the oil-trapped phenomenon can be avoided by reducing the pressure in the rubber balloon cavity.
Microstructure Characterization of EU INCEFA-SCALE 316L Stainless Steel Fatigue Specimens – Mechanistic Understanding
Authors: Vainionpää Aleks , Spadotto Julio , Que Zaiqing , Connolly Brian , Mclennan Alec , Arrieta Sergio , Huret Joseph , Damiani Thomas
Published: November 2023

A pressurized water reactor (PWR) primary environment can have a deleterious effect on the fatigue lifetime of austenitic stainless steels. One of the main goals of a five-year INCEFA-SCALE (INcreasing safety in NPPs by Covering gaps in Environmental Fatigue Assessment — focusing on gaps between laboratory data and component SCALE) project, kicked off in October 2020 and supported by the European Commission HORIZON2020 programme, is to develop an improved mechanistic understanding behind the effect of a PWR primary environment on the fatigue behavior of austenitic stainless steels through coordinated extensive characterization of as-machined and tested specimens at partner organizations.

This work focuses on the microstructure characterization of as-received austenitic stainless steel 316L plate material and as-machined fatigue specimens, as well as the preparation of guidelines on post-mortem characterization for the consortium. The presented microstructure characterization is carried out using light optical microscopy (LOM), scanning electron microscopy (SEM), and analytical electron microscopy (AEM) (including electron backscatter diffraction (EBSD), scanning/transmission electron microscopy (STEM/TEM), X-ray energy dispersive spectroscopy (EDS) and electron diffraction). The hardness, grain structure, inclusions, and delta-ferrite of the as-received 316L material were investigated. The surface roughness, machining-induced deformation layers, and ultra-fine-grained structure of as-machined ground and polished specimens were studied.

A ground surface finish leads to significantly higher machining-induced deformation, and surface roughness, with plenty of machining-induced cracks and defects extending a few microns into the bulk material, compared to a polished finish. The guidelines on the post-mortem characterization for the whole consortium can guide partner organizations in their posttest analysis for a direct comparison of the characterization data, which facilitates the mechanism interpretation.
Feasibility and Optimization of Nozzle Flapper System for Position Measurements of High-Speed Rotation Spindle With Aerostatic Bearings
Authors: Xu Peimin , Inaba Kazuaki , Takeishi Hisami , Kagawa Toshiharu
Published: November 2023

In recent years, due to the increased demand for semiconductors, there has been a need to increase the rotation speed and load of processing spindles. Spindles with aerostatic bearings were proposed as a solution to the above needs but lacked an effective position measurement as part of a compensation strategy. In this paper, measurements for spindle position control using the nozzle flapper system are proposed and verified through experiments under the rotation speed of 20,000 rpm. The individual and interactive influence of the multi-fluid structures, such as orifices, nozzle, and condition parameter supply pressure on the relation between the distance from the nozzle to the rotating body and the control pressure was experimentally studied. Meanwhile, securing static and dynamic characteristics is challenging because the distance between the shaft and the outer cylinder is small. This paper proposed a multi-hole nozzle system and conducted its static and dynamic characteristic tests in this case. In addition, the influence of the volume of the control room on the frequency response of the nozzle flapper system was discussed theoretically, and experiments verified the conclusion. This research can provide the design and optimization method of the nozzle flapper system for the high-speed rotation spindle position measurement and further study.
Sensitivity of Residual Stresses due to the Implementation of Local Post Welding Thermal Stress Relieving
Authors: Billon François , Willaume Pierre , Miguet Anthony , Moreau François
Published: November 2023

This study deals with an industrial case which consists in the Post Weld Heat Treatment (PWHT) of a butt weld of two shells of large diameter, high thickness and great length constituting parts of pressure equipment.

The limited local heated length is the source of local thermal gradients in the longitudinal direction because of the existence of transitions between hot and cold parts at the ends of the heated zones. These local thermal gradients generate residual stresses which are distributed in the so called “Heated Zone”, including the zone of the weld to be relieved named “Soak Band”, but also in the transition zones on either side of the heated zone, which we refer to as the “Gradient Control Band”.

The stress relief being carried out at a keeping average temperature of 615°C and according to a well-defined thermal cycle in time (heating and cooling rate and keeping duration), the evolution of the thermomechanical stresses due to the thermal cycle is calculated using a combination of the laws of plasticity and creep of the material of low alloy type 16MND5.

The plasticity and creep laws being fixed, and the residual stresses being determined for a reference heating configuration, the effect on the residual stresses of a simple variation in the extent of the thermal insulated zones are evaluated.
Flange Design Factors for the ASME BPVC Over Extended Parameter Ranges
Authors: van Zyl Gys , Francis Daniel , Ruffin Mark
Published: November 2023

The design of bolted flange joints according to the ASME BPVC uses the Taylor Forge method, first published in 1949. This method uses geometric factors (F, V and f for integral flanges and FL and VL for loose flanges) in the calculation of stresses in a tapered hub flange. The ASME BPVC, Section VIII, Division 1 provides charts and equations that can be used to calculate the factors. The charts are provided over a range of hub thickness ratios (g1/g0) from 1 to 5, and for hub length parameters (h/h0) between 0 and 2. Section VIII, Division 2 uses the same factors, but provides a different set of equations to calculate the factors. Within the parameter ranges of the Division 1 charts, the Division 1 and Division 2 equations give essentially the same results, but the methods diverge for parameters outside the chart ranges. This paper will describe the origin of the geometric factor curves and problems that arise when using the Division 1 and Division 2 flange design factor equations outside the parameter ranges of the Division 1 charts. New equations for the flange design factors that are valid over extended parameter ranges were derived from the original closed-form solution of the tapered hub flange and are proposed as an improvement to the current equations used in ASME Section VIII, Division 1 and Division 2.
Defect Recognition and Classification From Ultrasonic Phased Array Total Focusing Method Imaging Based on Random Forest
Authors: Wang Haibin , Fan Zhichao , Chen Xuedong , Cheng Jingwei , Chen Wei , Wang Zhe , Bu Yangguang
Published: November 2023

Pipeline transportation is one of the principal energy transportation methods. The safety performance of pipelines in construction and operation is closely related to the quality of welds. If the pipeline weld defects cannot be accurately identified promptly, late maintenance may cause leakage arising from the welding defects, which will give rise to considerably serious consequences. Ultrasonic phased array inspection is a widely used technology in non-destructive testing, which can significantly improve the sensitivity, coverage and accuracy of detection. In particular, the development of total focusing method imaging can obtain high-resolution images of cracks and other weld defects in pipeline. At the moment, imaging results necessitate manual judgment of defect type, which is highly dependent on the prior knowledge of the inspector. This leads to measurable amount of misjudgment, especially for the longdistance pipeline defect detection in which the amount of detection data is large and the imaging features are difficult to be recognized. Consequently, the automated recognition and classification of the defects is the emerging approach to resolve those. This study focuses on the linear defects and volumetric defects in welds (i.e. cracks and pores). Typical test blocks containing defects are fabricated and an ultrasonic phased array is employed to generate the images of the defects by using total focusing method (TFM) algorithm. To expand the sample size for small number of TFM results, the data augmentation approach is proposed and implemented. Then, the extracted features are input into the random forest algorithm, followed by debugging and optimization. The results suggest that the recognition and classification of defects from images are realized, and the accuracy rate of defect recognition is 96%.
Proposal of Performance-Based Seismic Fragility Concept Related to Failure Modes for a Piping System
Authors: Mano Akihiro , Sato Takuya , Ichimiya Masakazu , Kasahara Naoto
Published: November 2023

After the Great East Japan earthquake, the countermeasures for beyond design basis events (BDBEs) have become more important. For a component, mitigation of a consequence of a failure in terms of impact on safety performance is required in addition to prevention of the failure. One of the key issues regarding BDBE is a structural failure of a piping system subjected to excessive earthquakes. The piping systems have various kinds of failure modes such as collapse, break, ratchet deformation and fatigue. Collapse and break can lead to significance degradation of core cooling performance. On the other hand, small deformation or fatigue clack have small impact on the cooling performance. However, the existing seismic fragility does not take into account the failure consequence and its dependency on failure modes. In this paper, we propose a new concept regarding performance-based seismic fragility for BDBEs by including failure consequence. In the concept, the core cooling performance is taken as the most important safety performance. The performance degradation is evaluated as failure consequence considering the dependency on the failure modes by the following approaches. As for collapse, the approach differs by the existence of a crack in the piping system. In case a crack is not included, the large deformation is estimated to occur in the piping. Based on the deformation, change in geometry of a flow channel of coolant is estimated. Considering the flow channel, change in a flow rate is estimated. Finally, the performance degradation by the flow rate change is evaluated. On the other hand, in case a crack is included, a break of the piping and a leak from the break point can occur. Based on the break size, a leak rate and change in flow rate is estimated. Finally, the performance degradation based on the flow rate change is evaluated. As for ratchet, deformation of the piping due to an earthquake is estimated. Based on the deformation, the performance degradation is evaluated by the same approach as the collapse of piping with no cracks. As for fatigue, the size of a through-wall crack initiated by an earthquake is estimated. Based on the crack size, the performance degradation is evaluated by the same approach as the collapse of piping with a crack.
Application of Code Cases 2951 and 2964 for Elevated Temperature Design of Pressure Vessels Considering Load Durations
Authors: Kagita Gurumurthy , Addala Mahesh Babu , Krishna Pottem Penchala Sai , Srinivasan Balaji , Pudipeddi Krishnakant Venkat , V. R. Sripada Subramanyam
Published: November 2023

The rules of ASME B&PV Section VIII Code provide (i) allowable tensile stress at elevated temperatures based on time duration of 100,000 hours; (ii) external pressure charts which do not account for reduction of buckling strength due to creep under short or long-term loads. For short term operating conditions for which component design governed by an allowable tensile stress based on long term (100,000 hours) creep properties is unrealistically conservative and may be non-conservative in the case of very long load durations (> 100,000 hours). At elevated temperatures, the allowable compressive stress depends on magnitude of load and duration. The newly released code cases, Case 2951 ‘Alternative Approach for Operating Conditions (Including Occasional Loads) in the Time-Dependent Regime’ and Case 2964 ‘Allowable Compressive Stress in the Time-Dependent Regime’ provide procedures for elevated temperature design of pressure vessels considering load durations. In this paper, for successful implementation of these code cases, the key variables are reviewed and the inherent assumptions made in the development of these code cases are highlighted. Also, the code cases are applied for design of typical pressure vessel components and the results are compared with other relevant procedures which consider load duration into account.
Development of Stress Intensity Factor Solution for Surface Crack at Nozzle Corner in Reactor Pressure Vessel
Authors: Yamaguchi Yoshihito , Takamizawa Hisashi , Katsuyama Jinya , Li Yinsheng
Published: November 2023

The stress intensity factor (SIF) for a crack at nozzle corner is a key parameter in the structural integrity assessment of nozzle in a reactor pressure vessel (RPV). Although various SIF solutions for surface cracks at nozzle corners have been proposed, most focus only on the deepest point of the crack, and the information about geometric dimension of the nozzle corner is not clear. According to previous fatigue test results regarding the surface crack at the nozzle corner, the amounts of crack growth at the surface points were larger than that at the deepest point of the crack. Such results imply that SIFs at the surface points may be higher than that at the deepest point. It is necessary to provide SIF solutions for both surface and deepest points to increase the reliability of the structural integrity assessment. Through finite element analyses, this study developed SIF solutions for two surface points and the deepest point of a surface crack at the nozzle corners. The solutions correspond to the geometric dimensions of the nozzle corner and crack size.
Tribological Behaviour in the Underhead for High Strength Socket-Head Screws Coupled With Cast Iron and Tightened in Dry and Lubricated Condition
Authors: Croccolo Dario , De Agostinis Massimiliano , Fini Stefano , Olmi Giorgio , Scapecchi Chiara , Vincenzi Nicolò
Published: November 2023

The present paper investigates the influence of several design parameters on the frictional response at the underhead in a bolted joint, involving high strength socket-head screws: M8 class 14.9 with black oxidization coating. The experimentation deals with an underhead materials (Cast iron), lubrication conditions (dry, lubricated) and repeated tightening operations. The awareness of the actual friction coefficients, depending on the current operating parameters, is a useful tool, to support the most proper design of a bolted joint. The experimental campaign has been run by a testing rig for friction coefficient estimation, complying with the recommendations by International Standard ISO 16047 and the automotive Standard VW01131-1 in order to consider the effect of the tightening speed normally adopted in the automotive field. The axial preload generated upon tightening induces a high pressure on the remarkably small underhead surface of the utilized high strength socket-head screws and is therefore likely to affect the tribological response. Consequently, some differences may be expected with respect to the tribological behaviour of screws belonging to lower strength grades. This is particularly true, when tightening is done without bearing lubrication, and through several repeated assembly-disassembly operations. The collected data have been processed by the tools of ANOVA and F-Test, in order to assess the significance of each factor, as well as related interactions.
Investigations on Vibroacoustic Characteristics of Sandwich Plates With Viscoelastic Core Using Coupled FE-BE Method
Authors: Ji Ming , Sekiguchi Yu , Naito Masanobu , Sato Chiaki
Published: November 2023

The car body panel gets thinner as automotive lightweight technology advances, which affects NVH performance. To achieve the desired noise control, both radiation and propagation paths should be taken into consideration. It is suggested that Passive Constrained Layer Damping (PCLD) can be used to address the problems. In order to efficiently assess the acoustic vibration properties of a sandwich plate with a viscoelastic core, the coupled finite element and boundary element (FE-BE) method is used. The four-node plate element is used to simulate the plate. The direct boundary method is used to solve the Helmholtz wave equation for air. The coupled FE-BE method is used to calculate the radiated sound field under point excitation. The sandwich plate is made of two aluminum plates bonded by structural adhesive. The dynamic mechanical parameters of the adhesive are obtained by the modified Oberst method, which uses a composite beam with an aluminum base beam and a layer of adhesive. Then, the master curve is applied in the coupled FE-BE procedure. The acoustic pressure is measured by a microphone when an impact hammer hits a sandwich plate. Comparisons with both impact tests and the proposed FE-BE method are shown to prove the accuracy and computational efficiency for the modeling of the vibro-acoustic response of the viscoelastic sandwich plates.
Experimental Study of Combined Effects of Liquid-Solid Flow Erosion and Alkaline Acid Water Corrosion in Coal Water Slurry Gasification Unit
Authors: He Meng , Chen Sheng , Sun Li , Kang Haoyuan , Han Zhiyuan , Xie Guoshan
Published: November 2023

The combined effect of liquid-solid erosion and alkaline acid water corrosion (mainly NH4HS corrosion) always speed up wall thinning, punching, even breaking up leading to dangerous medium leakage and shorting the running period of coal water slurry gasification units. Comparison with three experimental date sets involving deionized water, NH4HS and deionized water, and particles and NH4HS solution are conducted in terms of loss weight amounts of SA106 Gr.B steel. This work aims to investigate the thinning damage rule under the combined effect of pulverized coal particle erosion and NH4HS solution corrosion, furthermore, a novel reduction rate prediction model including some key factors of NH4HS and particle concentrations and flow velocity is proposed to guide erosion shield for coal water slurry gasification units. The results show that the particle concentration has a small effect on particle erosion at a low liquid-solid flow velocity (3m/s). There is a shield effect on the reduction rate near wall until to 6% of particle concentration, therefore, flow velocity plays a dominant role for erosion at 6% of particle concentration. With the increase of NH4HS concentration or flow velocity, the erosion rate increases gradually. The particle concentration has less emphasis on the reduction rate than NH4HS concentration or flow velocity. Higher particle concentration is beneficial for avoiding the damage of corrosion films, and then inhibits eroding from NH4HS solution.
An Experimental and Numerical Modelling for SMAW
Authors: Gallée Sébastien , Gommez Florence , Sallez Nicolas , Brosse Alexandre
Published: November 2023

For many years now, FRAMATOME has used the numerical welding simulation for a better understanding of the phenomena involved during manufacturing process [1][2][3][4][5]. Numerical simulation allows a better understanding and predictions of the distortions and residual stresses induced during the welding process.

This paper deals with the numerical welding simulation of a SMAW mock-up. The specific stepped 20MND5 ferritic steel grade mock-up has a rectangular shape with a groove of 30 mm depth. The groove is filled by a coated electrodes welding process using a multi manual beads. To monitor the welding conditions as precisely as possible, temperature gradient within the mock-up base material, the interpass temperature and the outline evolution of the mock-up and the chamfer are recorded after each bead during the manufacturing process. To complete the input data available for the simulation and assist its validation, extensive characterization, including hardness mapping, micrographs, as well as residual stresses measurements, were conducted.

The results of the numerical simulation are compared to experimental data in terms of temperature, distortions and residual stress.
Evaluation of the API 579-1/ASME FFS-1 Equations for Equivalent Membrane and Bending Stress in Thick Wall Applications
Authors: Alstadt Steven , Sarzynski Melanie
Published: November 2023

For polynomial and arbitrary through-wall stress distributions, the API 579-1/ASME FFS-1 2021 Fitness for Service (API 579) standard provides equations for calculating equivalent static membrane and bending stresses. The membrane and bending stress values are then used in various stress intensity factor and reference stress calculations to evaluate crack-like flaws. In the 2021 edition, the equivalent static membrane and bending stress procedures are covered by equations 9B.1 to 9B.5 and 9C.1 to 9C.5. These equations were independently evaluated in this work for circumferential flaw configurations in cylinders and spheres. It was determined that the current equations produce reasonably accurate results for cylinders and spheres with large internal radius to thickness ratios (Ri/t). However, for thick-wall applications where Ri/t ≈ 5 or less, new equations are proposed to improve the accuracy. The main features of the new equations include representing the stress distribution as a function of the radial position and implementing integration in a cylindrical coordinate system. At large Ri/t ratios, the results from the new equations are practically the same as results associated with the current API 579 approach. The new equations are recommended as improvements for fitness for service assessments that involve circumferential flaws in thick-walled cylinders and spheres.
Validation and Refinement of Statistical-Based Fatigue Crack Initiation Model for Axial Flaws in Zr-Nb Pressure Tubes
Authors: Liu Cheng , Scarth Douglas
Published: November 2023

The Canadian Standards Association (CSA) Standard N285.8 requires evaluation of a detected in-service flaw in CANDU Zr-2.5Nb pressure tubes for crack initiation due to fatigue. Fatigue crack initiation experiments had been performed on notched specimens from irradiated and unirradiated pressure tube materials in a laboratory air environment. A statistical-based fatigue crack initiation model that covers the effects of flaw root radius, load rise time and irradiation had been developed, which was documented in the paper PVP2014-28942. The number of load cycles to fatigue crack initiation is predicted to decrease with an increase in load rise time. The load rise times of fatigue test data used in the development of the statistical-based model are no more than 50 seconds, however, there are transients with load rise times as long as nominally 60 minutes during the operation of CANDU reactors. A number of additional fatigue test data from both irradiated and unirradiated pressure tube materials with load rise times up to 1800 seconds have been generated to validate the application of the statistical-based model to transients with long load rise times. The statistical-based model has also been refined by including those additional fatigue test data into the model development. The validation and refinement of the statistical-based fatigue crack initiation model in an air environment have been documented in this paper.
Fatigue and Fracture Behavior of Aluminum Alloys in Gaseous Hydrogen
Authors: Shrestha Rakish , Ronevich Joseph A. , Michler Thorsten , San Marchi Chris
Published: November 2023

Fatigue and fracture properties of aluminum alloys do not appear to degrade in the presence of dry gaseous hydrogen, based on limited available data. However, more data are needed, particularly at higher hydrogen pressure and for higher strength grades, to reliably suggest broader use of aluminum alloys for hydrogen applications. In this study, we investigate the effect of gaseous hydrogen on fatigue and fracture behavior of four aluminum alloys: 5083, 2219, 7050, and 7475. Fatigue crack growth behavior of these alloys is investigated in air and in gaseous hydrogen at pressure of 1,000 bar. In addition, the fracture resistance of each alloy was determined in these environments. Results showed that gaseous hydrogen did not have a detrimental effect on either fatigue crack growth rate or fracture resistance of these aluminum alloys for the tested conditions. Interestingly, the fatigue and fracture properties showed a slight improvement in high-pressure gaseous hydrogen, which may be attributed to the absence of moisture.
Welding New Supports to Weld Overlay or Cladding in Existing Hydroprocessing Reactors
Authors: Zhu Sophia Xiaoxia , Kruse Ryan , Penso Jorge
Published: November 2023

In order to maintain profitable margins in the refining industry, hydroprocessing reactors occasionally require new internal support rings or gussets to accommodate revised catalyst bed heights or quantities. Historically, this has been solved by adding an internal skirt to raise or lower the effective distribution height, but this can create distribution issues and increases the complexity of the internals. An alternative approach is to weld new support rings or gussets onto the weld overlay or cladding of existing reactors. However, this approach is not commonly accepted, and many owners shy away from it to avoid the potential repercussions of performing the weld incorrectly. To address these concerns, this paper discussed the key considerations of this process associated with the degradation mechanisms, and provided guidelines on startup and shutdown, inspection, stress requirements and welding procedures in order to perform this process safely. Several case histories were presented for adding light load bearing attachments to the overlay or cladding of the hydroprocessing reactors. It has been demonstrated that welding new supports to the overlay or cladding of the hydroprocessing reactors can be managed safely and in a cost-effective manner when the proper design, shut down/startup procedures, inspection techniques, welding procedures and production controls are utilized.
High Strength Ferritic Steels for Hydrogen Service
Authors: Ortolani Matteo , Bortot Paolo , Sileo Michele , Escorza Erick , Connolly Matthew , Chandra Ashwini
Published: November 2023

Hydrogen is widely expected to become every day’s fuel in a decarbonized energy economy. Owing to its very low mass density, storing hydrogen efficiently in gaseous form requires significantly more elevated pressures than hydrocarbons. However, contact and interaction with hydrogen are known to be detrimental for container material properties, causing a decrease in ductility and toughness as it diffuses into the container walls.

In this context, high strength materials with good resistance to hydrogen embrittlement are desirable. Ferritic steels are widely used thanks to their availability and competitive cost; it is known, however, that a ferritic steel’s sensitivity to hydrogen embrittlement generally becomes worse as its strength increases. The magnitude of such phenomenon nonetheless varies with the selection of the alloy and its manufacturing process parameters; as such, it is possible to identify high strength steels that are more or less suitable for the construction of pressure equipment for hydrogen storage and transportation.

This work introduces a comparative assessment of different quenched and tempered, low alloy ferritic steels’ performance in a pressurized pure hydrogen gas environment, in terms of measured fracture toughness and fatigue crack growth rates. The findings are then discussed in comparison to similar alloys and manufacturing conditions.
Supplemental Structural Analyses Used in Support of Certification of the Defense Programs Package 3
Authors: Sakalaukus Peter J. , Barrett Nathan P. , Koeppel Brian J.
Published: November 2023

The Defense Programs Package (DPP)-3 is to be certified by the National Nuclear Security Administration (NNSA) Packaging and Transportation Division (PTD). Certification is based on successful physical testing of the package, and six certification test units (CTUs) have been subjected to the normal conditions of transport (NCT) and hypothetical accident conditions (HAC) outlined in Title 10 of the Code of Federal Regulations Part 71 (10 CFR 71). During regulatory testing of one of the CTUs, the drum lid closure bolt closest to the impact surface failed during the HAC 30-ft side drop. One of the testing goals for this CTU was to minimize the thermal pathway from the drum exterior shell to the containment vessel (CV) flange and O-rings, leading to the maximum damage scenario in preparation for thermal testing at 1475 °F. Therefore, the puncture bar impact proceeded as originally planned by striking the side wall of the package exterior closest to the location of the CV flange. This puncture bar impact did not attempt to exploit the region of the failed drum lid closure bolt to potentially cause more damage to the package. After the conclusion of regulatory testing, the DPP-3 package finite element model was used to numerically evaluate the effects of puncture bar impacts to the drum exterior in the vicinity of the failed drum lid closure bolt to further demonstrate the robustness of the DPP-3 design. Three alternate puncture bar impact locations and orientations were evaluated to demonstrate that these puncture bar impacts would not substantially reduce the effectiveness of the DPP-3 packaging. This paper describes the supplemental finite element models performed and structural analysis results that demonstrate the alternate HAC 40-in. puncture bar impact tests would have no deleterious effect on the performance of the DPP-3.
A Phase Field Method Based Fracture Analysis of Functionally Graded Plates
Authors: P. C. Sidharth , Rao B. N.
Published: November 2023

Due to the graded distributions of their material properties, functionally gradient materials (FGMs) have more complicated fracture behavior than homogeneous materials, making it difficult to simulate their failure mechanism. The current work makes use of special shape functions and informed mesh refinement schemes in conjunction with the famous phase-field method to render the fracture computations faster at the same time retaining accuracy in the prediction. To this end, exponential shape finite element shape functions are introduced instead of standard bilinear shape functions conventionally used in finite element calculations accompanying the phase-field method. The exponential characteristic of such special shape functions is made use of to reduce the mesh refinement level at crack propagation paths. This study suggests a learned orientation scheme for these shape functions, informed by an approximate analysis using bilinear shape functions carried out during the analysis itself. Fracture simulations are carried out in functionally graded plates with different gradation schemes, and their effect on fracture resistance is investigated. Computational efforts incurred in the present implementation are compared with existing schemes using bilinear shape functions.
Analysis of Piping Components for High Temperature-Example Problem
Authors: Adibi-Asl Reza
Published: November 2023

ASME Code Section III Division 5 (high temperature) primarily focuses on component design, with limited guidelines for piping analysis and design. Prior research has examined the analysis requirements of ASME Section III Divisions 1 and 5 with regard to piping analysis, and has presented design-by-rule piping formulae for analyzing Class A piping under elevated temperatures. This paper presents step-by-step procedures and formulations, using an example problem of a piping system under elevated conditions.
Comparison of the Fatigue Life in Hydrogen Environment Using ASME Section VIII, Division 3 and ASME Section VIII, Division 2
Authors: Kuscu Koray , Singh Mandeep
Published: November 2023

In recent years, hydrogen gas has been gaining favor as a valuable energy transition option to help reducing carbon emissions. This transition requires hydrogen storage and distribution infrastructure with consideration of failure modes such as hydrogen embrittlement that is typically not a concern for other fuel types. ASME BPV Section VIII, Division 3, Article KD-10 has special requirements for vessels in hydrogen service. Although Article KD-10 has been in existence since the release of 2007 Edition of the Code, few studies have been done to compare conventional ASME Section VIII, Division 2 fatigue evaluation in air environment with ASME Section VIII, Division 3 fracture mechanics-based evaluation in gaseous hydrogen environment. This paper presents a comparison study of the calculated fatigue life using these two methods (S-N in air vs fracture mechanics in hydrogen) for different crack-like flaw sizes with the consideration of the current rules in both ASME Section VIII Division 3 and API 579 / ASME FFS-1 Codes. The comparison in this paper utilizes fatigue and fracture data of material in hydrogen service published by Sandia National Laboratories and various authors.
Influence of Electrode Weave Width on Weld Heat Input
Authors: Tatman Jonathan , Hargadine Mitchell , McCracken Steven L.
Published: November 2023

In arc welding processes, heat input is a measure of the energy that is supplied to the workpiece to produce the molten weld puddle. Heat input is generally calculated by taking the arc energy (volts × amperage) divided by the electrode linear travel speed. The units are typically (kJ/cm or kJ/inch). The effect of electrode weaving or oscillating transverse to the forward linear travel speed can be difficult to account for in the heat input calculation. The ASME Section IX committee is considering addition of a new essential variable to account for this effect of weaving on heat input. This has been proposed due to the potential for employing a wide weave and calculating heat input using the forward advancement of the weld bead as the travel speed, which could result in excessive heat input. The concern is a procedure qualification record (PQR) qualified with a high heat input and a wide weave could be used to support a Welding Procedure Specification (WPS) that permits utilization of the same heat input with stringer beads. This paper includes a literature study and heat input measurements for stringer and weave beads, demonstrating that introducing this new variable is not urgently required, lacks technical basis, and may even be unsuitable.