bluuebunny/crossref_metadata_2025 huggingface dataset:
Enhancement and Optimization of Crack Signal Processing in Alternating Current Electromagnetic Non-Destructive Testing
Authors: Li Yong , Dong ShaoHua , Wang LuMing , Liu GuanYi
Published: November 2024

Metal structural elements frequently exhibit surface crack defects due to their operational conditions characterized by high strength, susceptibility to corrosion, and mechanical wear. To facilitate reliable forewarning and maintenance, crucial for averting safety incidents during equipment service, an accurate and stable inspection approach is indispensable. Currently, human intervention primarily dominates defect inspection, which results in restricted techniques and reduced efficiency. This paper concentrates on optimizing characteristic signals using the principles of Alternating Current Field Measurement (ACFM). Initially, a finite element analysis technique is applied to simulate and compute five parameters: excitation frequency, coil turns, excitation voltage, coil wire diameter, and lift-off height. The aim is to determine electromagnetic parameters that are well-suited for the inspection environment. Subsequently, for heightened inspection accuracy, we introduce a targeted curve-fitting method based on simulation outcomes. Specific methods are designed to address characteristic feature identification concerning crack length and depth, which includes a time-difference method and a binary-double calculation method. Furthermore, we delve into the inherent patterns between butterfly maps and crack profiles. This exploration leads to a novel crack profile prediction method grounded in butterfly map characteristics, thereby enhancing the array of crack risk assessment methodologies. Finally, we establish an experimental platform to examine various lengths and depths of groove-shaped cracks in A36 material. This experimental setup also concurrently reconstructs profiles of cracks featuring identical characteristic dimensions. Our experimental results indicate that characteristic inspection errors for crack length and depth amount to 5.98% and 3.86%, respectively. Moreover, the inspection errors for profile attributes, based on butterfly map information, linked to crack length and depth, stand at 6.50% and 7.89%, respectively. Our experimental outcomes underscore the rationality of our characteristic signal processing and optimization methods.
Development of 3D Dimensional Inspection Methods for Pressure Vessels Using Portable, Non-Contact, Infrared Laser Type 3D Scanner
Authors: Hanaki Aiko , Enoki Yukihiko , Kudo Akihiro
Published: November 2024

During factory inspections of pressure vessels, there are many cases of missed allocations of attachments such as nozzles, clips and saddles. These oversights typically come to light during the installation of piping connections and/or equipment platforms at the construction site, following the installation of the pressure vessel. Addressing the mis-installations in the piping has led to the construction schedule delay and cost increase. The lack of comprehension in dimensional requirements of pressure vessels by fabricators causes these troubles. Additionally, oversights in verifying these requirements by inspectors prior to pressure vessel shipment also contributes the issue. Accuracy of dimensional inspection result using conventional manual measuring depends on skills of inspectors especially for large pressure vessels. In addition, it takes a several days to prepare inspection report with prevalent method.

In order to address these issues, a recently advanced and rapidly evolving technology, the non-contact infrared laser type 3D scanner, is introduced for the purpose of “3D Dimensional Inspection” within the oil and gas industries. Advantages of infrared laser type 3D scanners are lesser initial investment and more portable with lesser restriction of regulations for international transportation against stationary laser type scanners.

This paper presents trial results inspected pressure vessel dimension and discusses the advantages and disadvantages of the 3D Dimensional Inspection. The prospects for its future application to project execution is introduced.
Benchmarking Screening Methods for Acoustically Induced Vibration
Authors: Swindell Rob , Hayashi Itsuro , Karczub Denis , Mann J. Adin , Horder Nick
Published: November 2024

A series of tests was performed on a mockup of a typical relief/blowdown system as part of a Joint Industry Project investigating the phenomenon of acoustically induced vibration (AIV). The system consisted of an NPS6x8 pressure relief valve, an NPS12 tailpipe and an NPS20 sub-header, and small-bore (NPS2) connections were installed in the tailpipe and header. The goal of the testing program was to provide high quality data to quantify the impact of various fitting types, different mitigation methods, and provide data for improvements and validation of AIV and FIV screening, prediction and assessment methods.

This paper describes the use of the derived test parameters (principally the measured dynamic strain response and associated fatigue damage accrual in conjunction with the process conditions under which the tests were performed) to benchmark various public domain screening methods for AIV which are commonly used in industry to assess the risk of an acoustically induced vibration fatigue failure occurring. The results of the benchmarking are used to identify the conservatisms (and in certain cases, the non-conservatisms) associated with the screening methods considered. Conclusions are drawn concerning the key aspects that should be incorporated within a screening assessment, including considerations for both short duration and continuous operation, and gaps in the current methods identified. It is noted that some screening methods are more suited to assessing systems with short duration operation, and suitable factors of safety should be used when the methods are applied to continuously operating systems. Recommendations are also provided for how these gaps may be addressed in the future.
Using ASME B31J Stress Intensification Factors (SIFs) to Improve A BS 7608 Fatigue Analysis
Authors: Harper Chris , Breaux Lyle
Published: November 2024

Standards like ASME B31J-2017 describe a methodology for calculating stress intensification factors (SIFs, or i-Factors) for metallic piping components like branch connection fittings and elbows. These SIFs are based on fatigue tests done on commercially available metallic components, and relate the stress that causes a through-wall crack in the component to the fatigue strength of straight butt-welded pipe. The SIFs consider many different variables of the geometry including component diameter and wall thickness.

Fatigue standards like BS 7608:2015 do not account for fitting geometry directly (stress calculations implicitly account for component geometry), focusing instead on weld joint details required for fatigue calculations. Standards like BS 7608:2015 are widely used and appear to more accurately simulate the fatigue failure of welded structures.

The goal of this paper is to outline a method to utilize the fatigue testing that is embedded in the ASME B31J SIF calculations to improve the accuracy of a fatigue analysis done using standard BS 7608:2015. Some consideration is required before using the standards together, due to different methodologies and S-N curves.

The paper includes several finite element analyses which test the conclusions of the paper. Additionally, calculations are done using the original testing data contained in ASME STP-PT-073 Annex E by A. W. Paulin.

The approach outlined in this paper is being adopted for use in the new API 579 Part 15 – Assessment of Piping Vibration. Specifically, API 579 Part 15 will permit the use of SCFs (stress concentration factors) derived using ASME B31J i-Factors (as outlined in Section 3) in certain limited situations, such as when SCF values for piping components are unavailable from FEA or strain gage testing.
Reliability Assessment of High Temperature/Pressure Steam Tube Dissimilar Metal Welding and Experimental Validation
Authors: Kim Jae Cheol , Park Jong Jin , Hoon Jegal , Hong Jong Ho , Perrin Ian
Published: November 2024

As the needs for coal power plant decrease, the needs for gas fired combined cycle power plant increase, and to decrease the emission of CO2, the steam conditions of heat recovery steam generator (HRSG) become more severe. For plant efficiency increase, the temperature of steam increases so that 9Cr ferritic steel cannot be used so austenitic stainless steel must be employed with consequent dissimilar metal welding (DMW) locations. In this study, integrity assessment analysis and validation test were carried out for the dissimilar welding composed of SA-213 T92, SA-213 S30432 and ERNiCr-3.

From the welding simulation, weld residual stress was predicted, and following post weld heat treatment (PWHT) the normal operating conditions were used for the finite element analysis to predict structural reliability. A hyperbolic sine law was adopted for the creep modeling, and creep life was predicted considering the properties of partially transform region of T92 side heat affected zone. In addition, considering the characteristics of HRSG of frequent start up and shut down, low cycle fatigue was assessed for the cyclic operation. The cyclic stress-strain curves for the materials were obtained from incremental tests, and nonlinear kinematic hardening model parameters of Chaboche type were determined and the cyclic operation was analyzed.

Experience of long-term operation of the DMW tube of the material combination in this study has been secured from USC grade coal power plant. However, to respond to the needs for the frequent start up and shut down of HRSG, reliability for low cycle fatigue must be proved, so low cycle fatigue mockup test was performed. Tube mockup of the DMW material combination was fabricated, and low-cycle fatigue apparatus was constructed using an induction heating device and a pressurizing device using nitrogen gas. Realistic operating temperatures and pressures were imposed for over 10,000 cycles and damage of the welding part was investigated.
Visualization of Combined Decomposition and Relief Processes in High-Pressure Systems
Authors: Röblitz Aaron , Berning Jarne , Busch Markus
Published: November 2024

Preventing decomposition is of outmost importance in polymer chemistry, as it can lead to significant equipment damage and production losses. As decomposition cannot be completely prevented by the formation of hotspots, e.g. due to insufficient heat removal, a sound knowledge of the decomposition characteristics and the necessary relief process is of enormous importance. Some critical factors in these processes are the flame front velocity, the maximum pressure and temperature as well as the rate of pressure change and the total venting time, which influence both processes and are therefore decisive for the safety of a polymerization plant. The investigation of the described parameters is carried out in this paper using a view cell. The influence of ignition and relief positions, relief and closing pressures, as well as initial conditions are considered. The focus is on the conditions in a high-pressure separator as well as in a reactor, e.g. in LDPE production. Data acquisition is achieved using fast response pressure and temperature sensors and a high-speed camera to provide time-resolved results that provide information on the combined decomposition and relief process.
Substantiating the Design of a U-Tube Heat Exchanger’s Tube-to-Tubesheet Joint: Demonstrating Conformance in Accordance With The Principles of ASME BPVC III Class 1 Nuclear Components and TEMA
Authors: Shore William , Morris Alex
Published: November 2024

This paper presents the work conducted by Rolls-Royce to substantiate the design of a U-Tube Heat Exchanger’s (HE) tube-to-tubesheet joint, including demonstrating conformance with the ASME Boiler and Pressure Vessel Code (BPVC) Section III-NB rules for Class 1 components and the Standards of the Tubular Exchanger Manufacturers Association (TEMA).

The U-tube HE tubesheet forms part of the boundary between the shell-side and tube-side fluids. Tube-to-tubesheet joints of the HE locate the tubes within the tubesheet and consist of a hydraulically expanded region and a seal weld. Finite Element Analysis (FEA) could not accurately model the seal weld due to its small size causing singularities in the crevice region, generating unrealistic peak loads. Furthermore, local geometric constraints limited the use of a full-strength weld in lieu of a smaller seal weld.

Consequently, ASME BPVC Section III NB-3353, 4350 and 5274 were used in conjunction with the TEMA Class R and Class C rules to demonstrate safety and provide a robust design substantiation for the joint without FEA. Conformance to ASME BPVC Section III-NB and compliance with the principles of TEMA demonstrated that joint failure and subsequent fluid leakage will not occur.

This paper also describes the correlation between adhering to the rules of the ASME BPVC Section III-NB and the TEMA standards and the mitigation of common failure mechanisms for tube-to-tubesheet joints. The risk of tube pull-out, fatigue, environmentally assisted cracking and weld failure were shown to be low when qualitatively assessed with knowledge of adherence to the ASME BPVC Section III-NB code.
Applications and Considerations of Fitness-for-Service Methods to Real-World Environments of Crack Networks
Authors: Rosario Robert , Mollitor Barrie , Jackson Peter
Published: November 2024

The article highlights the importance of periodic field evaluations, Fitness-For-Service (FFS) applications, and industry experience by dissecting three real-world scenarios and their complementary nature. It covers two plants’ historical and technical backgrounds, discusses field procedures, and explains post-inspection tasks. Lifetime projections followed as engineering calculations were applied to flaw characteristics.

Plant A case studies 1 and 2 resulted from thermal quenching, and Plant B case study 3 was from operating excess and maintenance deferment. Common grounds across all case studies include preliminary diagnostics rooted in field observations, plant personnel account of the events, property damage, and circumstances that led to pressure-part component failure. Additional investigations expand the scope with laboratory analysis, modeling and simulation, and industry literature application. Each case study is a fitting example of common events affecting large-bore power piping worldwide. Those components installed outside the Heat Recovery Steam Generator (HRSG) serve combined cycle plants.

Asset management and industry professionals can extract common practices from all case studies that might reduce the probability of rapid localized degradation at their stations. Prompt identification of such variables prevents future catastrophic damage or, worst case, the irreversible loss of personnel lives. An opportunity to produce energy responsibly stands firm on proactive maintenance and timely damage recognition.
Research on Intelligent Monitoring Systems of High Voltage Direct Current Interference in Oil and Gas Pipelines
Authors: Liu Guanyi , Dong Shaohua , Jiang Zitao , Wang Luming , Chen Gengsheng , Wang Jiuzhen , Liu Xing
Published: November 2024

The western region of China is rich in oil, natural gas, hydropower, wind power, and other energy sources, while the economically developed eastern coastal areas exhibit a higher energy demand. To solve this problem, it is necessary to build high Voltage Direct Current Transmission lines and oil and gas pipelines for long-distance energy allocation. When the ground electrode in the HVDC line is discharged, the pipeline will be interfered by HVDC. Therefore, the complexity of HVDC stray current corrosion factors will bring the corrosion risk to the buried pipeline, resulting in oil and gas leakage, and even lead to a series of serious accidents such as fire and explosion. At the same time, the cathodic protection and interference parameter detection of long-distance pipeline need to collect the relevant data manually, which is not only time-consuming and labor-intensive, but also requires the business ability of the relevant personnel. In this paper, the performance of cathodic protection acquisition equipment and the construction technology of monitoring remote transmission function are studied. The structure and existing problems of the current intelligent monitoring remote transmission equipment system were analyzed and summarized. On this basis, a modular design of intelligent monitoring of oil and gas pipeline with HVDC interference is proposed and verified by experiments. The purpose of this paper is to provide reference for the further development and upgrade of the remote monitoring equipment system of oil and gas pipelines under HVDC interference, so as to ensure the safe and reliable operation of the pipeline.
Reliability-Based Safety Factor for Pressurized Components Considering Creep-Fatigue Failure
Authors: Wang Xiaoxiao , Chen Haofeng , Luan Weiling
Published: November 2024

Currently, the structural assessment procedures mainly rely on deterministic analysis considering the bounding values of the design parameters, and by adopting a safety factor, sufficient strength reserve is maintained to satisfy the uncertain factors. This safety factor is determined by the extensive expert experience, with redundant conservativeness included more or less. In this study, the reliability-based safety factor is developed by the established probabilistic Linear Matching Method framework (pLMM), to deal with the engineering component assessments under thermal-mechanical loads, where the uncertainty of design conditions is quantitatively taken into consideration. This risk management-based evaluation strategy is able to facilitate the design robustness of critical infrastructures in terms of Low Cycle Fatigue and Creep-Fatigue failures.
Intelligent Defect Recognition of Pipeline Welds Based on Deep Learning for Phased Array Ultrasonic Testing Images
Authors: Zhang Ruyun , Dong Shaohua , Zhang Laibin
Published: November 2024

Non-destructive testing is a crucial process to ensure the quality of pipeline welding. Phased Array Ultrasonic Testing (PAUT) provides real-time scanning and imaging, and compared to radiogaphic testing, PAUT is harmless to humans and the environment, with accurate defect localization and high sensitivity. However, due to its relatively short history of widespread adoption, there is a shortage of professionals and teams trained in PAUT compared to traditional testing techniques such as radiography. In this paper, we study the intelligent defect recognition technology for welds in pipelines using deep learning-based Phased Array Ultrasonic Testing images. We establish a database of PAUT images for pipeline welds, including various types of defect detection images. Subsequently, we perform image peprocessing, to enhance features andreduce noise, thereby improving image quality. Multiple algorithms are employed for defect edge extraction to accurately identify weld defects. Finally, by analyzing the principles and issues of target detection, we improve existing models and frameworks and propose a novel deep learning-based framework for defect classification and localization in PAUT images of pipeline welds. Experimental results demonstrate that the proposed approach achieves high accuracy and localization precision in defect recognition of PAUT images for pipeline welds, providing effective technical support for automated evaluation of weld defects in pipeline systems.
Proposal of a New Flaw-to-Surface Proximity Rule for the Re-Characterization of a Subsurface Flaw Into a Surface Flaw
Authors: Lacroix Valéry , Dulieu Pierre , Hasegawa Kunio
Published: November 2024

When a subsurface flaw is detected close to the free surface of a pressure retaining component, it must be assessed whether the subsurface flaw shall be transformed into a surface flaw in accordance with flaw-to-surface proximity rules. Those re-characterization rules assume implicitly that if the interaction between the subsurface flaw and the free surface is too high, the remaining ligament is susceptible to break leading to this re-characterization of the subsurface flaw into a surface flaw. This re-characterization process from subsurface to surface flaw is adopted in all Fitness for Service (FFS) Codes. In the Section XI of ASME Boiler & Pressure Vessel Code, the limit value for this proximity rule depends on ratio be-tween the subsurface flaw to the free surface distance (i.e., the remaining ligament) and on the flaw depth. This limit value does not depend on the flaw aspect ratio.

This paper firstly demonstrates that, for a given flaw depth, the interaction between the subsurface flaw and the free surface of the component depends highly on the flaw aspect ratio. Therefore, the current flaw-to-surface proximity rule should account for this parameter as well. Then, the paper proposes an interaction limit criterion and presents a new limit value for the flaw-to-surface proximity factor, depending on the flaw depth, the remaining ligament and the flaw aspect ratio as well.
Revision of Long-Term Creep Strength of Base Metal of ASME Grade 91 Type Steel
Authors: Kimura Kazuhiro , Yaguchi Masatsugu
Published: November 2024

In a preliminary study on the creep rupture life scatter estimation of base metals of ASME Grade 91 type steel under actual service conditions performed by one of the authors, it was found that the creep rupture life curves and allowable stress of Grade 91 type steel pipes which were determined in Japan in 2015 may not be appropriate. Therefore, those were re-evaluated in this work by the Assessment Committee on Creep Data of High Chromium Steels, which consists of the Federation of Electric Power Companies of Japan, material producers, power plant manufacturers, and research institutes in Japan, which had evaluated the material in 2015. Creep rupture data were again provided for the re-evaluation by each organization of the committee, and creep rupture strength was assessed using the latest dataset of Grade 91 type steel by the region splitting analysis method in the same manner as in the previous study. It was suggested that the assessment should be performed at once simultaneously regardless of the product form such as pipes, plates, and tubes. As a result, the creep rupture life curves and allowable stresses of steel pipes were revised to the lower strength side than those in 2015. Furthermore, on the basis of the data and knowledge regarding the effect of chemical composition on the creep life of Grade 91 type steel, revisions to Japanese material codes regarding the chemical composition of Grade 91 type steel were proposed to prevent the production of low-strength Grade 91 type steel.
Effect of Temperature on Fretting Wear and Corrosion of 316L Stainless Steel In the Liquid Lead-Bismuth Eutectic (LBE)
Authors: Chen Hui , Zhang Shengzan , Tan Wei , Zhu Guorui
Published: November 2024

The change of temperature in liquid lead-bismuth eutectic(LBE) can lead to the formation of oxide film with different properties on the surface of structural steel. In the lead-cooled fast reactor, the heat transfer tubes are the important place for heat exchange in the steam generator. Affected by flow-induced vibration, the heat transfer tubes and the supports occur relative movement, resulting in fretting wear. The dense oxide film can protect the heat transfer tubes. Therefore, according to the temperature in operating conditions, this paper focuses on the influence of different temperatures on the fretting wear and corrosion of 316L austenitic stainless steel in LBE. The temperature ranges from 250°C to 600°C. With the increase of temperature, the friction coefficient decreases first and then increases, and the wear depth keeps increasing. When the temperature is 350°C–450°C, the wear depth increases slowly. Many small exfoliation layers and oxidized abrasive debris appeared on the wear scar surface. Meanwhile, no obvious dissolution corrosion occurred. When the temperature is 600°C, the wea depth increases rapidly to 9.63μm. Large exfoliation appeared on the wear scar surface. The NiO content on the wear scar surface decreases sharply to 2.36%, which indicates that the dissolution corrosion occurred severely, and the corrosion resistance of austenitic stainless steel decreased. 350°C–450°C is a temperature range, which is conducive to reducing the damage of fretting corrosion. The experimental results of this paper can provide reference data for the development of nuclear structural steel for lead-cooled fast reactors.
Tilting Manhole Cover: A Nonlinear Spring-Mass System
Authors: van de Meulenhof Niels F. , Tijsseling Arris S. , Vasconcelos Jose G. , Hou Qingzhi , Bozkuş Zafer
Published: November 2024

Manhole covers are potential “dancers”. They may leave their resting state and start “dancing”. They may hover, move up and down, tilt, rotate, bounce, make noise, flip over, or even fly up into the air. In general, their motion looks chaotic, probably due to the nonlinear dynamics governing the system.

The authors have previously derived basic models of dancing manhole covers covering the translational vertical motion of free covers and the rotational motion of hinged covers. In the current contribution the basic model is extended with tilting (without hinge) and bouncing behavior. Some fundamental problems and assumptions are discussed. Preliminary numerical results are shown together with 3D visualizations.

Scientific curiosity into a mysterious phenomenon has been the motivation for this study. The obtained equations governing the manhole cover’s motion may serve as boundary conditions in hydraulic-pneumatic models of sewer-manhole systems (think of geysering and ventilation).
Commissioning and Scalability of a High-Pressure Multi-Zone Autoclave for Polymer Synthesis
Authors: Schreiner Nicola , Weigel Christoph , Kirsch Julian , Gockel Lena , Busch Markus
Published: November 2024

On industrial scale, low-density polyethylene (LDPE) is produced at pressures and temperatures of up to 3500 bar and 300 °C. High-pressure tubular and autoclave reactors are used. Autoclave reactors usually show a high height-to-diameter ratio and are used as multi-zone autoclaves with additional feed points along the reactor axis. On laboratory scale most reactors used are stirred vessel with only one reaction zone. By means of residence time behavior and the possibility of temperature profiles, both types of reactors differ drastically. To bridge the gap between laboratory and industrial scale, this work shows the commissioning of a high-pressure multi-zone autoclave on lab-scale. An in-house designed stirrer is used, to divide the autoclave into three zones. During high-pressure polymerization experiments different zones of the autoclave are addressed. The response is given by temperature profiles. Subsequent, the effect on the molecular weight distribution is elaborated and discussed both experimentally and simulatively.
Influence of Resonant Acoustic Mode Shape on Source and Sink Patterns in the Wake of a Single Cylinder Based on Howe’s Energy Corollary
Authors: Shaaban Mahmoud , Rashed Mostafa R. , Mohany Atef
Published: November 2024

The interaction between the acoustic field and periodic flow structures in the wake of a cylinder can self-excite resonance and lead to undesirable noise and vibrations in heat exchangers. The underlying energy exchange mechanism responsible for the emergence of a resonant acoustic field depends on the coupling between flow and acoustic parameters in time and space. Previous investigations have demonstrated that a net positive acoustic energy rate over a complete coupled cycle is essential to sustain resonant conditions. However, existing models have primarily focused on the excitation of the fundamental acoustic mode, considering only one-way coupling, resulting in predominantly qualitative findings. This study utilizes Howe’s energy corollary to determine the amount of acoustic energy produced and absorbed by the flow moving downstream of a single cylinder in a rectangular duct. By considering full coupling, resonant mode shapes are self-excited, enabling the computation of the acoustic and flow fields, acoustic energy generation, and the phase delay between the acoustic field and the lift force. Results provide detailed insights into the coupling mechanism governing the first three transverse acoustic modes, which can be excited by the unsteady vorticity shedding from the cylinder within the relevant velocity range of interest.
Static Incremental Analysis With Modal Inertia Force Taking Into Account the Elastoplastic Nature to Estimate Elastoplastic Displacements of Structures
Authors: Taniguchi Tomoyo , Kaieda Takumi
Published: November 2024

Estimating the maximum elastoplastic response of structures during earthquakes is of interest to designers. To date, only the time history analysis can calculate elastoplastic responses of structures. However, such responses are considered lack generality, because dependence of responses on accelerograms cannot be eliminated, and thus they are not always adequate as the design quantities. Contrary, the design response spectrum is generated to provide a normative response which should be considered in design. Therefore, if we can calculate elastoplastic responses of structures based on the design response spectrum, structural healthiness during the severe earthquake can be verified. Such a motivation in mind, this paper develops a static incremental analysis to estimate elastoplastic displacements of structures. Its essence is that; 1) use modal properties according to the spring state and define the modal inertia forces with/without intercept of the restoring force from the absolute acceleration spectrum value, 2) define the intensity of base excitation after yielding so as to make the absolute acceleration in the global coordinates system continue and 3) calculate the maximum elastoplastic displacement of each floor by the modal combination rule. The displacement calculated form the proposed procedure is compared with that computed. Accuracy of the proposed procedure is clarified.
Performance Assessment of Additive Manufacturing Components for an Ex-Core Nuclear User : Valve Component – NUCOBAM Project
Authors: Misler Roxane , Hernandez Rebeca , Fernandez-Viña Antonio , Nardone Steve , Hary Benjamin , Bertelle Norman
Published: November 2024

In recent years, the nuclear industry has been exploring the potential of additive manufacturing (AM) to create components for nuclear power plants (NPP’s). Roadmaps have been developed within this sector, outlining the steps required to enable the use of AM components’ production. In this context, several projects have been initiated, including the European project NUCOBAM [1]. The overarching objectives of the NUCOBAM project (Nuclear Components based on Additive Manufacturing) is to tackle the technical challenges associated with manufacturing NPP’s components using AM [2].

One of the key elements within the NUCOBAM project involves the performance assessment of an ex-core component, specifically a valve. The AM process and alloy within the project’s scope are Laser Powder Bed Fusion (L-PBF) and the austenitic stainless steel grade 316L. This assessment will be incorporated into a methodology for qualifying components produced trough AM that adhere to nuclear codes and standards. This paper will offer a detailed presentation of the study related to additive manufacturing valve body and the qualification methods for this component, along with the procedures developed within the NUCOBAM project.
Review of Secondary Stress Treatment in the R6 Fracture Assessment Procedure
Authors: James Peter
Published: November 2024

This paper is looking to review ongoing developments related to the treatment of secondary stresses in low temperature fracture such that best practice and pertinent information are identified.

In recent years there has been considerable activity on work associated with understanding the impact of secondary stresses on fracture. Here, secondary stresses are defined as displacement-controlled stresses such as thermal and weld residual stresses that do not contribute to plastic collapse. The consideration of such secondary stresses is crucial to the ongoing justification of high integrity components. The range of work internationally that has focussed on the treatment of secondary stresses includes work performed as part of the R6 development programme, work within other UK national programmes into fracture and work published internationally in the open literature. Given the wide range of activities and potential developments elsewhere, it is considered timely to provide a review of the recent work to understand the areas of progress, relative strengths and weaknesses, potential gaps in understanding, and how this may lead to developments in the associated guidance (such as R6 and BS7910).
Flow-Induced Pulsation in a Header Configuration
Authors: Belfroid Stefan P. C. , Driessen Ronald J. A. , Gonzalez-Diez Nestor , van De Krol Bart
Published: November 2024

Double Tjoint configuration can generate high pressure pulsation amplitudes due to the interaction between vortex shedding and the acoustic resonance. Specific geometries are more susceptible due to the orientation between the acoustic field and the flow field. One geometry often encountered in the field is a header configuration. The arche-type of this is a header with an inlet and outlet (of equal diameter to the header diameter) at ¼ and ¾ of the header. The goal of this paper was to evaluate the sensitivity of the inlet diameter, the inlet location and the outlet location on the pulsation amplitude. A 150 m, 3m header was used in conjunction with a 75mm outlet and an inlet diameter of 25, 50 or 75mm. The inlet location could be varied between 5 locations, the outlet in 3 locations. Only in a limited number of configurations, a flow dependent frequency was measured. The source does not correspond to the sources found in literature for the arche-type. No consistent Strouhal number could be defined. The inlet did act as broadband source for the excitation of the main resonance modes. Smaller diameter inlets lead to a high number of modes excited with overall a high amplitude whereas a larger diameter leads to an overall lower amplitude with excitation of only lower modes.
Towards a Data-Driven Evolutionary Model of the Cyclic Behaviour of Austenitic Steels
Authors: Dorward Hugh , Knowles David , Mostafavi Mahmoud , Peel Matthew
Published: November 2024

Understanding the cyclic behaviour of austenitic stainless steels is important in assessing the integrity of pipework in a wide range of applications including in the nuclear industry. Design and assessment codes such as R5 address the cyclic evolution through phenomenological approaches which can also be informed by models such as Armstrong-Frederick, Ohno-Wang and Chaboche-Lemaitre. They aim to predict the evolution of combined isotropic and kinematic hardening under cyclic loading. More recently, advances have been made in the development of both phenomenological and physically based crystal plasticity models in modelling the cyclic behaviour of steels, however the application of these is limited by their computational expense.

In this study, the application of data-driven approaches for modelling the cyclic evolutionary behaviour is investigated. A synthetic cyclic dataset is produced through crystal plasticity finite element simulations to represent experimental cyclic data. A functional principal component analysis technique is proposed as a reduced order representation of the cyclic data to act as a data-driven parameterisation of the hysteresis curve. This method is shown to be able to accurately recreate the hysteresis loops with only a small number of scalar parameters.
Hydrogen Permeation Behavior of the Liner of Type IV Hydrogen Storage Cylinders Under Different Pressures
Authors: Qi Zhipeng , Shi Hao , Hua Zhengli , Yang Miaomiao , Peng Wenzhu
Published: November 2024

Type IV hydrogen storage cylinders are increasingly recognized as a prime solution for hydrogen storage in hydrogen fuel cell vehicles (HFCVs). Compared with other cylinders, this type of hydrogen storage cylinder is comprised of a polymer inner liner wrapped with carbon fiber composite material, offering advantages such as light weight, low cost, and fatigue resistance. Nonetheless, the polymer liner, typically fabricated from high-density polyethylene (HDPE) or polyamide (PA), exhibits notable hydrogen permeability, posing an increased risk of hydrogen permeation leakage. This constitutes a primary factor influencing the safety of its operational application in hydrogen storage contexts. In this paper, experiments on hydrogen permeation were executed under varied pressure conditions on two representative liner materials (HDPE and PA6) of Type IV hydrogen storage cylinders, aiming to scrutinize the relationship between hydrogen permeation performance of different liner materials and pressure, and to encapsulate the differences and consistencies between materials. Based on the test results, a finite element simulation was conducted on the hydrogen permeation behavior of the cylinder liner to probe into the effects of various liner high-pressure side pressures and liner thicknesses on the hydrogen permeation behavior, culminating in the formulation of the hydrogen permeation law of Type IV hydrogen storage cylinders. The outcomes of this study and the elucidated hydrogen permeation laws provide a fundamental reference for further research and design endeavors aimed at enhancing subsequent Type IV cylinder liners.
Prediction of Tensile Behaviour of Electron Beam Welded SS316L Using Crystal Plasticity Framework
Authors: Ashraf Farhan , Demir Eralp , Mokhtarishirazabad Mehdi , Mostafavi Mahmoud , Knowles David
Published: November 2024

Electron beam welding (EBW) is particularly attractive to the nuclear sector for joining future components due to its characteristic features, efficiency, and high productivity. In terms of its characteristics feature, EBW creates a narrow heat-affected zone and uniform energy density that minimize distortion and residual stresses in the weldment. Moreover, EBW can join thick components with uniform chemistry, however, it creates significant microstructural heterogeneities and different texture inducing directional properties in the weldment. The weld microstructure consisted of large columnar grains relative to the equiaxed grains of varying sizes in the surrounding parent material.

This work aims to study the effect of microstructure heterogeneities on the mechanical response of weldment using a crystal plasticity framework. The grain size and texture dependence of local deformation have been a grand challenge to model the mechanical response of metals. Here, we implemented a finite element crystal plasticity framework named “University of BRIstol cryStal plasTicity sOLver” (BRISTOL) that considers the effect of heterogeneous microstructure to predict the mechanical properties of the weldment in different loading directions. The comparison of model results with experiments shows that the proposed length-scale dependent model predicts accurate stress-strain response of the weldment in the longitudinal and transverse directions.
The Mechanical Behavior of Corrosion Resistant Alloys at Elevated Temperature With Internal Hydrogen
Authors: Ronevich Joseph , San Marchi Chris , Narasimhachary Santosh , Palmert Frans , Sheng Shilun , Wanjura Stefan
Published: November 2024

Structural materials used in combustion or power generation systems need to have both environmental and temperature resistance to ensure long-term performance. As the energy sector transitions to hydrogen, there is a need to ensure compatibility of highly-alloyed austenitic steels and nickel-based alloys with hydrogen over a range of temperatures. Hydrogen embrittlement of these alloy systems is often considered most detrimental near ambient temperatures and low temperatures, although there is some evidence in the literature that hydrogen can affect creep behavior at elevated temperature. In the intermediate temperature range (e.g., 100–400°C), it is uncertain whether hydrogen degradation of mechanical properties will be of concern. In this study, three alloys (304L, IN625, Hastelloy X) commonly used in power generation systems were thermally precharged with hydrogen and subsequently tensile tested to failure in air at temperatures ranging from 20°C to 200°C. At 20°C, the hydrogen-precharged condition for all materials exhibited loss in ductility with relative reduction of area ranging between 32% and 57%. The three alloys exhibited different trends with temperature but, in general, the relative reduction of area improved with increasing temperature tending towards noncharged behavior. Tests were performed at a nominal strain rate of 2 × 10−3 s−1 in order to minimize loss of hydrogen during elevated temperature testing. Hydrogen contents from the grip sections were measured both before and after testing and remained within 10% of starting content for 100°C tests and within 8–23% for 200°C tests.
ASME VIII-3, Nonmandatory Appendix G Total Effective Axial Clamping Preload Derivation
Authors: Ritter Erick R.
Published: November 2024

This paper rederives the ASME Boiler and Pressure Vessel Code, Section VIII - Rules for Construction of Pressure Vessels, Division 3 - Alternative Rules for Construction of High Pressure Vessels (ASME VIII-3), Nonmandatory Appendix G - Design Rules for Clamp Connections, Wc parameter, which is the total effective axial clamping preload on one clamp lip and hub shoulder for gasket seating or assembly. The derivation herein shows that the current definition of Wc is potentially half of what it should be. This paper is substantiated with both hand calculations and finite element analysis (FEA) and will attempt to provide background in the ongoing discussion of whether or not the current code has an error.

Other parameters in the ASME VIII-3, Nonmandatory Appendix G such as HG (difference between total effective axial clamping preload and the sum of total hydrostatic end force and total joint-contact surface compression), H (total end force required for operating or assembly conditions), and others may have similar issues that will need correction if the conclusions of this paper are accepted. Additionally, ASME Section VIII, Division 1 and Division 2 (ASME VIII-1 and ASME VIII-2) have similar definitions that may need correction.
Design of Jacketed Pressure Vessels Introduction to an Innovative Methodology Based on Formulae
Authors: Rohart Philippe
Published: November 2024

When pressure vessels are intended to transfer heat, and require temperature control, jacketed vessels can constitute an interesting technical solution. Quite common in the field of pharmaceutical industry and chemical engineering, it is composed of a main capacity (where an exothermic or endothermic chemical reaction can take place), with an external cavity, where a cooling or heating fluid is circulating.

Such equipments can theoretically be designed by analysis (DBA). However, it also cumulates difficulties: temperature variations and gradients (due to heat transfers), buckling (due to external pressure), and also fatigue (due to load cycles). Therefore, preparing a calculation note in order to justify the mechanical strength of such an equipment remains a challenge.

The French pressure vessels code, CODAP, led a set of studies, in order to provide innovative and simplified rules, based on formulae (DBF). Several types of jackets were considered, differing by their geometries. This paper describes the rules recently published in the chapter C12.2, dealing with U-shaped jacketed vessels. It provides its technical bases, its scope (in terms of geometry, material parameters, loads considered, failure modes covered, ...), and the design criteria. It finally details the developments and evolution to come in the next versions of CODAP.
Life Prediction With Material Hardening Models for High Temperature Cyclic Loadings
Authors: McGuire Ryan , Rajasekaran Ramesh , Ching Hsu-Kuang , Bankston David
Published: November 2024

This study addresses the challenges associated with predicting deformation and cyclic behavior in reactor components operating at elevated temperatures. It explores a potential solution by combining two conventional models to achieve more accurate results. While creep models and isochronous stress-strain curves aid in long-term deformation prediction, cyclic behavior often relies on simplified models such as isotropic and kinematic hardening. This work aims to augment the accuracy and efficiency of inelastic analysis by fine-tuning parameters within a combined isotropic and kinematic hardening model tailored to specific materials. A rigorous validation process was undertaken to ensure reliability, involving comparisons with advanced viscoelastic models. The outcome is a reliable and efficient inelastic model that can be employed to analyze components within TerraPower high-temperature nuclear reactors. The methodology calibrates predetermined percent contributions from a database of material properties derived from strain-controlled tests. An iterative process optimizes isotropic and kinematic hardening values, ensuring convergence that resulted in a precise material model. The proposed approach, leveraging a combination of kinematic and isotropic hardening methods, presents a robust model for engineers to analyze components in high-temperature reactors. This contribution enhances reliability and efficiency in structural design and maintenance, addressing the limitations of traditional models.
A Review: The Effect of Laminate Parameters on the Performance of Fibre-Reinforced Composite Pressure Vessel
Authors: Wu Haoyu , Chen Zhiwei , Ji Fang , Jia Xiaoliang , Wang Jinhui
Published: November 2024

Sustainable development has become the main theme of the world’s economic development nowadays. Hydrogen energy, as a new type of clean energy, has received extensive attention and focused research from countries in recent years, and the search for safe, efficient, economical and more energy-saving hydrogen storage technologies is the main direction of hydrogen energy utilization development. With the increasing requirements for the light weighting of hydrogen storage pressure vessels and the growing maturity of composite material design and processing technologies, various pressure vessels have evolved from metal tanks to fiber-reinforced pressure vessels (FRPVs) over the past decade or so, mainly to reduce weight and increase pressure ratings. Fiber-wound pressure vessels are an important direction for the future development of high-pressure vessels, and during the preparation of fiber-reinforced pressure vessels, the parameters of the winding and molding process play a crucial role in the performance of the products. In this paper, the effects of design and process parameters such as resin mass fraction, fiber volume fraction, winding tension, winding path, winding pattern, etc. on the forming process of FRPV winding layer and the performance and quality of the finished products are reviewed, and different optimization techniques for each parameter are summarized, and the problems and development trends are proposed to provide a reference for the research on the forming process of fiber-wound pressure vessels.