bluuebunny/crossref_metadata_2025 huggingface dataset:
Transport of Large Nuclear Power Plant Components – New SCO-III Regulations and Mechanical Design Assessment
Authors: Komann Steffen , Wille Frank , Linnemann Konrad , Ramsay Jeff , Reiche Ingo
Published: November 2024

The decommissioning or refurbishment of nuclear facilities necessitates either the storage or disposal of large radioactive components such as steam generators, pressurizers, reactor pressure vessels and heads, and coolant pumps, to list the major contributors. These components or objects are large in size and mass, measuring up to approximately 6 meters in diameter, up to 20 meters in length, and weighing over 400 000 kg. In many situations, the components are transported off-site to a storage, disposal or recycling/treatment facility. Previously, many large objects had to be transported under special arrangement.

The latest 2018 edition of the International Atomic Energy Agency (IAEA) Regulations for the Safe Transport of Radioactive Material, No. SSR-6, incorporates regulations for the shipment of contaminated, but not activated large objects as a new category of surface contaminated object, SCO-III, based on the IAEA “performance package” concept.

This paper provides background and practical guidance on these regulations. Additionally, first experiences with SCO-III in the approval process are presented.

For SCO-III components a mechanical assessment regarding the tests specified in the transport regulations SSR-6 for demonstrating ability to withstand normal conditions of transport is required — a free drop of the package onto an unyielding target and a penetration test have to be investigated. Large components are unique objects; therefore, it is not possible to choose experimental testing as assessment method. The application of a complex numerical analysis for mechanical proof is necessary.

The assessment of the loads takes place based on local stress distributions.

The large nuclear components have typically been transported in an unpackaged manner, so that the external shell of the component provides the containment wall.

The paper will represent the methods, which are used for the evaluation of the mechanical integrity of the object for transport approval.
Proposal of Negative Stress Ratio R for Fatigue Crack Growth Rates of Austenitic Stainless Steels in Air for ASME Code Section XI Based on Trend in Experimental Data
Authors: Negyesi Martin , Yamaguchi Yoshihito , Hasegawa Kunio , Lacroix Valery , Morley Andrew
Published: November 2024

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

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

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

It is known that the toughness reduction of Cr-Mo steels owing to temper embrittlement can be alleviated by heat treatment above a certain temperature. This phenomenon (i.e., de-embrittlement) is, therefore, worth considering when there is a concern regarding brittle fracture in aging pressure equipment. In this study, vintage 1¼Cr-½Mo steels were taken from fluid catalytic cracking (FCC) reactors / orifice chambers and catalytic reforming reactors which started operation in 1970s. The steels were then heat-treated at various temperatures ranging between 530 °C and 720 °C (986 °F and 1,328 °F). Charpy impact toughness of as-received and heat-treated samples was investigated. The results showed that de-embrittlement could be achieved regardless of the impurity levels and operation periods. The result further indicated that the heat treatment at 570 °C (1,058 °F) was still effective as a de-embrittlement heat treatment for aging 1¼Cr-½Mo steels. This temperature is lower than the temperature noted in API RP571.
Effects of Welding and Constraint Conditions on the Welding Residual Stress and Hardness of Type 316 Stainless Steel Pipe
Authors: Li Suo , Yamaguchi Yoshihito , Katsuyama Jinya , Li Yinsheng
Published: November 2024

Flaws due to stress corrosion cracking (SCC) were recently detected in welded joints of austenitic stainless steel piping lines in pressurized water reactors. Welding-induced high hardness and tensile residual stress are known as one of the main factors affecting SCC. In this work, thermal-elastic-plastic coupled three-dimensional finite element analyses were performed to investigate the distributions of welding residual stress and hardness in butt-welded joints of Type 316 stainless steel. Different heat inputs were applied to the pipe welds, including normal heat input, high heat input and very high heat input. Two different axial constraints were considered for the welded joints, i.e., both ends free or clamped. Simulation results were compared with experimental data such as welding thermal cycle, axial shrinkage, and residual stress for validation. The effects of heat input and constraint condition on the welding residual stress and hardness were discussed in detail. The predicted results show that there are high hoop residual stress and high hardness in the 13-pass welded joint with normal heat inputs, and high axial residual stress in the 4-pass welded joint with very high heat inputs. The axial welding residual stress and hardness can be reduced by mitigating the axial constraint in the welded joint.
Life Assessment of Metals Used in Fusion Using R5 and RCC-MRx
Authors: Belrhiti Younes , Hamelin Cory , Knowles David , Mostafavi Mahmoud
Published: November 2024

In the European DEMOnstration Fusion Power Plant (DEMO) fusion reactor, in-vessel components face significant thermomechanical loads. They can experience severe damage due to high thermal load cycles, coupled with severe electromagnetic loading and unprecedented levels of irradiation damage. Cooling fluids are used to extract the heat to reduce operating temperatures and for energy production. Other elements, like the shielding liner and reflector plate supports, may also experience severe creep-fatigue and irradiation damage.

To assess the high-temperature structural integrity of such components, procedures in R5 and RCC-MRx are used to assess creep-fatigue, whereby fatigue is assumed from pulsed reactor operation and creep from sustained load at high temperatures. This project aims to conduct a creep-fatigue assessment of a representative joint, tungsten-to-tungsten via copper brazing (W-Cu). However, due to a lack of data on such fusion-specific joints, two more conventional joints are studied: a 316L similar metal weld; and a 316L-to-10CrMo9-10 dissimilar metal weld.

Methodologies used for creep-fatigue assessments within R5 and RCC-MRx are detailed and compared, then applied to each material using the appropriate materials data. The two procedures share similar underlying approaches however, some subtle differences may become important within an assessment.
Assessment of Circumferential Crack-Like Flaws in Piping Accounting for Partial Compressive Zone Using Contact Elements
Authors: Dulieu Pierre , Van Ende Antoine , Lacroix Valéry
Published: November 2024

When a circumferential surface crack-like flaw is detected in a pipe subjected to a bending load, it may be partially located in a compressive zone, preventing the crack faces to open locally. In order to take that phenomenon into account, contact elements at crack faces should be used in numerical Fracture Mechanics analyses to avoid crack face interpenetration. However, usual Fracture Mechanics analyses do not consider such contact at crack faces as the non-linearity introduced in the system resolution leads to excessive computation time for industrial applications. Consequently, interpenetration of the crack faces occurs which is not realistic. This behavior is observed when the mode-I Stress Intensity Factor (SIF) has negative value along the crack front.

In the present work, Fracture Mechanics simulations are conducted to assess the impact of including contact conditions at crack faces on mode I SIF considering linear elastic material conditions. Then, the behavior of the crack faces with respect to increasing load is assessed through J-integral calculations considering elastic-plastic material conditions. Those results along the crack front in the tensile zone are assessed for different cracks and types of loads. All these analyses intend to draw up a statement about the necessity to model contact conditions at crack faces in flaw acceptability assessments.
Research on Determination of Obround Shell Thickness
Authors: Jin Yao
Published: November 2024

The analysis and design of obround components has been difficult and complex due to the lack of theoretical solutions. The existing design codes use empirical formulas to determine the wall thickness for obround components. To make the wall thickness acceptable, trial and error is inevitable. Since the results are not precise, the thickness determined is not the minimum required thickness, MRT. The closed-form solution proposed recently makes it possible to directly determine the wall thickness for obround components. In this paper, a new method for determining the MRT of obround shells is proposed. In the method, an obround shell is imagined as being stretched laterally from a cylindrical shell or parent cylinder. As the parent cylinder continues to be stretched, the wall thickness of the obround shell should continue to increase to remain the maximum hoop stress constant. The MRT of the obround shell should be related to the MRT of the parent cylinder and the straight shell length of the obround shell. Parametric study is performed to investigate the relationship among them. Empirical expressions are used to describe those relationships. Using the proposed design method, the determination of the MRT of obround members becomes the determination of the MRT of the parent cylinders and additional parameters. The MRT of obround members is determined directly. The case study demonstrates that the proposed method is an efficient and accurate design process for obround members. The possibility of using this method in Fitness-for-service is explored. The new method is used to reassess operational safety in the event of vessel materials deterioration.
Derivation of Input Distributions for Probabilistic Evaluation of PT/CT Contact in CANDU Reactors
Authors: Nadeau Eric , Baniak Adrian
Published: November 2024

CANDU® nuclear reactors are comprised of 380 or 480 fuel channels, each having a pressure tube installed concentrically inside a calandria tube. Each PT contains 12 fuel bundles. Four helicoidal annular springs, also known as spacers, provide support to the PT and prevent contact between the two tubes.

In 1983, the PT in channel G16 at the Pickering A Unit 2 ruptured unexpectedly. It was found that, in the older CANDU design, the loose-fitting spacers might move large distances from their design locations resulting in long unsupported spans. This eventually leads to the PT contacting the CT, with the contact spreading axially over time. Because the moderator on the outside of the CT is much cooler (about 70 °C) than the PT (> 260 °C), this results in a cold region in the PT at the location of contact. The dissolved hydrogen in the PT can precipitate in the form of hydrides at the cold spot to form zirconium hydride blisters, which may crack, initiate delayed hydride cracking (DHC), and eventually lead to PT rupture.

The industry has been relying mostly on the Spacer Location and Repositioning program to prevent PT/CT contact. The PT/CT gap profile is also measured on a subset of FCs in each reactor during regular fuel channel inspections and during SLAR campaigns. To assist the CANDU operators with a risk-informed FC management program, a probabilistic methodology was developed to assess the probability of PT rupture resulting from contact and blisters.

The most critical inputs are the PT creep distribution and the end-slope distributions at each end of the PT. The derivation of those distributions for the reactor core is performed using a benchmark methodology comparing the predicted and measured PT/CT gap profiles. A probabilistic reactor core assessment is then performed to rank individual FCs by risk and determine a SLAR scope.

Since PT/CT gap is also measured in many of the inspected channels, there is a need to integrate the additional information from the gap data into the assessment to avoid identifying at-risk channels unnecessarily for subsequent SLAR scopes. For this purpose, a channel specific benchmark methodology has been developed to refine the PT creep and end-slope distributions in FCs with measured gap.

Therefore, for channels with no PT-CT gap information, the assessment is performed with core distributions, while for channels with PT-CT gap information, the assessment is performed with channel specific distributions.
Research on Effects of Surface Finishing and Mean Stress on Fatigue Lives of Notched Specimens: Mean Stress Effect for Notched Specimens of Carbon Steel
Authors: Wang Yun , Nakane Motoki , Hirano Akihiko , Takanashi Masahiro , Kitamura Yoshihide
Published: November 2024

DFC3 and DFC4 subcommittees in the Japan Welding Engineering Society (JWES) have investigated the mean stress effect and its correction methods on fatigue analysis for carbon steel STPT370 (equivalent to SA-106 Gr.A) in consideration of stress concentration.

The Modified Goodman approach has been widely applied for mean stress correction. However, according to the investigation results from polished smooth specimens, the Smith-Watson-Topper (SWT) approach showed higher rationality for mean stress correction. In this work the applicability of SWT approach was discussed for notched specimens.

Polished smooth specimens and notched specimens with stress concentration factors of 1.5 and 1.8 were prepared for fatigue tests. Firstly, the regression curves of both smooth and notched specimens were obtained from fully reversed fatigue tests. Secondly, mean stress fatigue tests for notched specimens were conducted at several loading levels. For both stress concentration factors, the data of mean stress fatigue tests dispersed below the regression curves of fully reversed fatigue tests, indicating that the fatigue strength of notched specimen could be reduced by the mean stress effect for this material. The elastoplastic analysis of Finite Element Method was conducted for estimating Mises equivalent stress and Mises equivalent strain at the bottom of notch. With these parameters, the equivalent stress amplitude Seq of SWT approach was calculated. For comparison purpose, Seq was also calculated by correcting the nominal stress amplitude and mean stress directly with the stress concentration factor Kt. Finally, the applicability of SWT approach for notched specimens was discussed by comparing the equivalent stress amplitude Seq to the fictitious elastic stress amplitude Sa of the regression curve of smooth specimens.

According to the results of this work, it was concluded that the equivalent stress amplitude Seq of SWT approach was available to mean stress correction for the notched specimens of STPT370.
Evaluation of Single Stud Replacement in Standard Piping Flanges
Authors: Brown Warren , Godfrey Darryl , van Zyl Gys
Published: November 2024

Single Stud Replacement (SSR, also known as hot-bolting) on the flanges of in-service piping is required on occasion to replace excessively corroded bolting, environmentally cracked bolting or to reduce the scope of work during turnarounds. Removal of a stud from a pressurized bolted joint is associated with an increased risk of leakage and a method to evaluate risk associated with SSR is currently under consideration for inclusion as an appendix in ASME PCC 1. In this paper, the authors explore the suitability of different methods of analysis for SSR, including the calculation of the reduction in gasket stress due to load loss associated with removal of a stud and using this result to assess the potential for leakage of the joint.

An advanced SSR calculation method was developed and applied to standard ASME B16.5 flanges of all sizes and classes. The results were then verified against finite element analyses performed on a sample of standard flanged joint configurations. Current ASME PCC-2 guidance regarding pressure limitations for safe SSR are also examined, in order to establish whether or not they are effective or appropriate. The results and conclusions of this study are presented, along with a discussion on how the evaluation method can be used to assess risk in combination with other factors that have an influence on the probability and consequence of leakage during SSR.
Study on the Discharge Characteristics of Multi-Hole Nozzles and Feasibility Verification for Built-In Nozzle Flapper in Air Spindle
Authors: Xu Peimin , Inaba Kazuaki , Takeishi Hisami , Kagawa Toshiharu
Published: November 2024

To improve the production efficiency of semiconductors, in the past we proposed a compensation system that uses a nozzle flapper as a distance sensor to adjust the air bearing to improve processing accuracy. Although the feasibility of the single-hole nozzle flapper system has been verified in past research, its static characteristics and structure cannot meet the requirements of the air shaft in actual engineering applications.

In this paper, we propose the design of the multi-hole nozzle flapper from the perspective of static characteristics. On the other hand, to ensure the compactness of the air spindle, a built-in nozzle flapper was designed. The static properties of the two types of nozzle flappers and the structural parameters that influence them were experimentally explored.
Using Zero Added Corrosion Allowance for API 650 Tank Components For Various Refining Services
Authors: Ardaniel Zesan , Shargay Cathleen , Basic Michael , Soltaninia Shahab
Published: November 2024

Storage tanks are commonly used equipment in many industries and for refining, they are typically designed in accordance with API 650 [1]. API 653 [2] is used once the tank enters service for setting the minimum inspection and repair requirements for maintaining the tank integrity. Many designers add corrosion allowances to carbon steel storage tank shell, bottom, and roof plates. However, doing this can lead to redundant or excessive corrosion allowances as some “extra thicknesses” are already obtained using API 650 designs. These “extra thicknesses” are shown by comparing the initial required thicknesses in API 650 (without added corrosion allowance) to the corroded thicknesses which require repair in API Standard 653. The differences are, by definition, corrosion allowances. This paper shows the thickness calculations for each major tank components, including the shells and bottoms, per both the API 650 and API 653 standards. In addition, this paper provides recommendations for adding additional corrosion allowances in a few highly corrosive tank services in refining and other similar industries. However, this analysis shows that using zero added corrosion allowance is appropriate for many services as the built-in corrosion allowance is already sufficient.
The Impact of Tube Array Compactness on the Generation of Acoustic Resonance
Authors: Noufal Rasha , Kishawy Hossam , Mohany Atef
Published: November 2024

This study presents an experimental investigation into the effects of tube array compactness on self-excited acoustic resonance. The primary focus is on varying the number of rows and columns in the tube array, with rows ranging from 1 to 9 and columns from 2 to 3. The experimental results demonstrate a clear correlation between the compactness of the tube array and the occurrence and strength of self-excited acoustic resonance. Specifically, an increase in the number of columns was found to significantly enhance both the occurrence of excitation and the amplitude of the generated acoustic pressure. Additionally, increasing the number of rows led to the excitation of higher acoustic modes. These modes were observed to synchronize with the wake of the tube array, as evidenced by phase-locked particle image velocimetry (PIV) measurements. This synchronization indicates a complex interaction between the acoustic field and the fluid flow, wherein the phase of the excited acoustic mode’s particle velocity plays a critical role.
Study on Industrial Computed Tomography Detection and Identification of Inclusion Defects in Thick-Wall Polyethylene Pipe Butt Fusion Joint Within Nuclear Power Plant
Authors: Shi Yan , Tao Yangji , Shen Zitao , Shi Jianfeng , Miao Cunjian , Tang Ping , Guo Weican
Published: November 2024

High-density polyethylene pipe exhibits notable corrosion resistance and mechanical properties, and has been applied in nuclear power plants. Due to operational efficiency and safety considerations, polyethylene pipe used in nuclear power plant generally features considerable wall thickness, which poses a huge challenge for radiographic non-destructive testing of the embedded defects. In this study, the effects of X-ray source tube voltage, the number of digital radiography image merging, and the number of scanning frames utilized for three-dimensional computed tomography image reconstruction on the quality of industrial computed tomography images of polyethylene pipe butt fusion joint with a wall thickness of 80 mm were systematically researched. A method for detecting and identifying inclusion defects in thick-wall polyethylene pipe based on industrial computed tomography technology and image morphological method was proposed. It was found that the critical parameter impacting defect recognition was contrast to noise ratio rather than signal to noise ratio. For inclusion defects that were easily missed, the Top-Hat algorithm was used to automatically identify inclusion defects in thick-wall polyethylene pipe butt fusion joint. Additionally, these computed tomography results were validated by phased array ultrasonic testing results, indicating its potential for quality surveillance and failure analysis of polyethylene pipe within nuclear power plants.
Stress and Strain Analysis of Sealing Cup With Internal Groove of Pipeline Inner Inspection Tool in Dented Oil and Gas Pipeline
Authors: Wang LuMing , Dong ShaoHua , Li Yong , Liu GuanYi , Zhang Hang , Tian Cheng
Published: November 2024

As an important mode of oil and gas transportation, pipelines will produce different forms of defects with the increase of service life and the change of external environment. Regular inspection in pipeline is an important way to ensure the safe operation of pipeline. As an important driving component of the pipeline inner inspection tool, the reducing ability of the sealing cup determines whether it can have stable passability when the inner diameter of the pipeline changes or when defects such as dents occur in the pipeline. This article designed a conical sealing cup with an internal groove structure, and the kinematic simulation model of the pipeline inner inspection tool in the non-destructive straight pipe was established based on the finite element method. A push experimental platform was established for the study, and strain data of the sealing cup before and after entering the pipeline were collected. The trend of change was in good agreement with the simulation curve. In order to avoid the stuck of pipeline inner inspection tool in the pipeline dents, the simulation study was conducted on a 6%OD dent defect pipeline using a 19mm thick sealing cup as an example. The study showed that the groove morphology of the cup in contact with the defect pipeline stretched towards both sides, and the surrounding area of internal groove contracted inward to promote the overall diameter change of the cup. Compared to the cup without groove, the maximum contact stress was significantly reduced, which proves that it has better diameter reducing ability and higher passability. According to the model introduced in this article, it can provide guidance for the application of sealing cup with internal groove.
Non-Destructive Testing Study of Hydrogen Storage COPVs Based on Digital Shearography Technique
Authors: Wen Ange , Ma Li , Li Yifan , Wang Shoulong , Liu Changchen , Ying Kaidi
Published: November 2024

Composite overwrapped pressure vessel (COPV) is a vital component of the high-pressure hydrogen storage system used in hydrogen fuel cell electric vehicles (FCEV). However, the heterogeneity of fiber reinforced polymer (FRP) and the influence of the manufacturing process often result in manufacturing defects such as delaminations and cracks. These defects exhibit random variations in size and location, which not only leads to complex local mechanical behavior but also poses challenges in their detection. This study presents the utilization of digital shearography techniques for non-destructive defect detection in COPVs subjected to internal pressure. A Type III COPV of product model CHG3-383-55-35S/A (according to Chinese standard GB/T 35544) was subjected to various loading states and shear conditions in the experimental investigation. During the test, the characteristic shear fringe patterns caused by the local displacement gradient distortion was recorded in shearograms. The shearography technique leverages the understanding that defect-induced distortion in the displacement gradient is translated into anomalies in the fringe pattern. By analyzing the characteristic fringe patterns obtained in different loading state, the use of shearography approach effectively identified and revealed the size and location of embedded delaminations and surface micro-cracks. In the end, the study also explored the influence of the measurement parameters, such as inspection field of view (FOV) and shear direction, on the detection sensitivity of shearography results. The work aims to provide a reliable and efficient testing scheme for defect detection in COPVs.
GDDM: A Solution for Cross-Domain Class Imbalance and its Application in Fault Diagnosis
Authors: Fan Xiaoxuan , Duan Lixiang , Jiang Lumeng , Yu Shengyang
Published: November 2024

Timely and accurate fault diagnosis of mechanical equipment helps improve the safety of pipeline system. In practical cross-domain diagnostic tasks of mechanical equipment, there exists a problem of cross-domain class imbalance, which makes it difficult to effectively transfer knowledge from the source domain to the target domain. To address this issue, this paper proposes a Graph Data-Driven Method (GDDM) for cross-domain discriminative feature extraction. The key of this method lies in using a designed Graph Construction Model (GCM) to extract discriminative features across domains. Specifically, the GCM uses pearson similarity to measure the inter-class differences between samples and uses them as the weights for connections between graph nodes. Based on this, it constructs graph data that integrates sample features and their relationships, effectively modeling inter-class differences among samples. Furthermore, by inputting the graph data into a spectral graph convolutional network, it extracts discriminative features, overcoming class bias and achieving effective cross-domain knowledge transfer under the condition of cross-domain class imbalance. The proposed method is applied to the publicly available bearing dataset from the Case Western Reserve University, and experimental results demonstrate its effectiveness and stability in handling cross-domain class imbalance data, achieving effective cross-domain knowledge transfer and fault diagnosis.
Laboratory Testing of Buried Pipelines Subjected to Ground Displacement Due to Seismic Motion
Authors: Chang Che-Yu , Yang Hsuan-Chih , Chang Wei-Kuang
Published: November 2024

Ground displacement is considered the major natural hazard in causing damage to pipelines. Although the most effective method to reduce pipeline damage is routing the pipelines away from the ground movement potential areas, the pipelines in Taiwan unavoidably pass through faults, soil liquefaction potential areas, and sensitive areas of landslides, given that thirty-six active faults are crossing the island. Currently, available researches show that quasi-static testing is utilized to study the pipeline behavior under fault displacement. This paper presents laboratory testing design and results of buried pipelines subjected to ground displacement due to seismic motion. Pipelines are buried in a uniaxial shear box which is designed to introduce fault displacement caused by seismic motion. Different pipeline diameters are tested for comparison to study the diameter effect of pipelines. Protection measures such as different backfill materials and various burial depths are also tested to possibly offer suggestions on pipeline damage mitigation methods. The dynamic behavior of the pipelines is presented by the measurements collected by the strain gauges and accelerometers located on the pipelines. This study provides valuable information on the dynamic behavior of buried pipelines subjected to ground displacement due to seismic motion, which can enhance the design of the pipeline systems for seismic damage mitigation.
Study on Fracture Characteristics of Pipeline Girth Weld Based on Curved Wide Plate Tensile Test
Authors: Zhang Tieyao , Shuai Yi , Zhang Junjie , Shi Lei , Lv Zhiyang , Zhang Yinhui , Xia Gang , Li Xingtao
Published: November 2024

It is the premise and foundation of pipeline integrity evaluation to clarify the fracture toughness and strain capacity of pipeline girth weld. The curved wide plate is very close to the full-size pipeline in geometric size. Compared with the small-size specimens in the laboratory, the crack tip constraint state of the curved wide plate specimen is the closest to the real pipeline structure, which is the main way to study the deformation ability of the girth weld in the pipeline industry. In this study, wide plate specimens with different girth weld positions of 1016 mm × 15.0 mm L485M pipeline were intercepted, and different sizes of cracks were machined in the weld center of wide plate specimens. The slow rate uniaxial loading of wide plate specimens with cracks was carried out by kiloton tensile testing machine until the specimens were broken. During the test, the double COD (Crack opening displacement) gauge was used to monitor the opening displacement of the crack mouth near the crack, four high-precision displacement sensors were used to monitor the deformation of different positions of the specimen, and 52 strain gauges were used to monitor the axial and circumferential strains of different positions of the specimen. Through the experimental study, the strain response and fracture characteristics of the curved wide plate specimen with weld center crack under external load are obtained, which provides a data basis for the subsequent extensive parameter research, and also provides a reference for the safety evaluation of the cracked pipeline.
Sensor-Less Semiactive Damper That Automatically Switches Damping Force Using 3-Phase Motor and Relay
Authors: Matsuoka Taichi
Published: November 2024

The author developed a sensor-less semiactive damper that consists of a three-phase direct drive motor whose damping force is automatically switched by a rectifier circuit and relay, using the motor instead of a speed sensor. It is more compact and has higher performance compared to previous damper using DC motor. The direct drive motor is attached to the end of the shaft of the ball screw mechanism. Since the voltage between the motor terminals is proportional to the rotation speed, when the speed exceeds a border level, the voltage rises to the operating voltage of the relay, which closes the load circuit of the relay and causes a short circuit between the terminals, switching to the high damping force. The resisting force characteristics of the damper were measured by experiments, and a theoretical equation was derived. Next, the damper was attached to a one-degree-of-freedom system, and seismic wave excitation experiments were conducted. Experimental results show a little advantage in vibration reduction in the semiactive case which switches automatically, compared to a passive case where the damping coefficient of the damper is not switched. The experimental results agree with the calculated results mostly, and vibration control effect of the damper is confirmed.
An Overview of Codes and Standards for Electrolyzer Applications
Authors: Quackenbush Karen , Panicker Jitesh
Published: November 2024

This paper provides an overview of key codes and standards relating to electrolyzers. It will highlight similarities and differences between requirements published in ASME Section VIII, Division 1 Code Case 3078, ANSI/CSA 22734, NFPA 2, and applicable national and international standards. The paper concentrates on design considerations, materials requirements, and pressure testing requirements.
Tensile Testing for Determination of Mechanical Properties of Recycled PET-G Plastics
Authors: Alvarez Avianna , Ma Qin , Mckenzie Janice
Published: November 2024

Polyethylene terephthalate glycol (PET-G) has become one of the most widely used industrial thermoplastics due to its superior characteristics when compared to PET as well as other common plastics in industry. Because of its unique and favorable characteristics, PET-G has wide applications for making medical devices. The research teams led by Professor Michael Moor and Professor Michael Davidson at Loma Linda University, School of Allied Health Professions and Department of Orthotics & Prosthetics (O&P), have been working toward developing low-cost injection molding equipment to provide affordable, viable, and feasible O&P care for the most economically challenged individuals around the world. As part of their work, recycled PET-G plastics were melted and then thermoformed into plaster molds under various conditions. Their mechanical properties are highly desirable.

In this study, tensile properties of the PET-G recycled plastic dog-bone coupons were obtained and tested for modulus of elasticity, yield strength, tensile strength, and ductility. ADMET eXpert 7600 equipped with MTESTQuattro Materials Testing Software was used as the testing machine. The load cell was 1000 lb. in capacity with crosshead movement, and the vertical test space can accommodate up to 41 inches. For consistent testing, ASTM standards were employed in preparation of the specimens and testing procedures. It was found that the present recycled PET-G plastic yields results of tensile strength of approximately 47 MPa, 0.2% offset yield strength of approximately 35 MPa, tensile modulus of approximately 1.9 GPa, and ductility in the range of 170–250 percent elongation. All these findings are in agreement with literature for similar recycled PET-G plastics.
Failure Analysis and Materials Degradation Properties Assessments in an Aged Hydroprocessing 347H Austenitic Stainless Piping
Authors: Batts Kevin , Hau Jorge , Penso Jorge , Caldwell Eric , Dalal Mitul
Published: November 2024

A leak occurred on the suction 347H SS piping of a pump connected to one of the two reactors of a train during start-up of a hydrocracker unit while the other two-reactor train was online. Operations initiated shutdown activities and emergency response.

Destructive testing revealed a crack in a weld in the pump suction piping. This weld had recently undergone inspection. The results showed no indications of a crack. The UT phased array method using shear waves is an industry standard, but this crack was undetectable with standard NDE due to a combination of the thickness of the pipe, weld root geometry, and the weld metal properties. These features caused sound waves to reflect in a way that prevented distinction of waves reflected from a defect.

The crack in the pump suction line of the reactor had initiated at a stress riser on the surface geometry of the weld root. The weld had impact testing results in the range of 18–42 J (13–31 ft-lb), and elongation in the range of 15–16% at ambient conditions, suggesting some embrittlement have taken place. For new 347H SS pipe and welds, approximately 108–136 J (80–100 ft-lb) would be the expected impact test range and > 35% elongation. The toughness and elongation had been reduced by the precipitation of brittle phases over the service life of the weld at about 427 °C (800 °F). The usual maintenance procedure to dismount the pump was achieved by hitting the flange joint with sledgehammers. This introduced high strain rate loading that caused the cracking in these embrittled welds.
Formulation of the Stress Corrosion Crack Growth Rates Based on the Theoretical Strain Rate Model for Light Water Reactors
Authors: Koshiishi Masato , Akazawa Dan , Miura Yasufumi , Kako Kenji
Published: November 2024

This study developed a formulation method for SCC growth rate based on SCC growth theory and the theoretical equation of strain distribution ahead of the crack tip. The SCC growth rate in a light water reactor environment is usually expressed in the form of a power law of the stress intensity factor, K. However, the power law of K was originally introduced with reference to the Paris law in fatigue crack growth and it is not based on SCC growth theory. Based on the theoretical equation for the strain rate ahead of the crack tip of a growing crack, it is appropriate to express the SCC growth rate in the form of a power law of log(K/K0). On the other hand, the conventional equation in the form of a power law of K is based on the strain distribution ahead of the stationary crack and it is not theoretically appropriate for growing cracks. Applicability of the proposed formulation method was also confirmed for several types of materials in the present study.
Research on Effects of Surface Finishing and Mean Stress on Fatigue Lives of Notched Specimens - Definition of Fatigue Life of Notched Specimen Using Crack Growth Analysis
Authors: Itatani Masao , Ogawa Takuya , Takanashi Masahiro , Wang Yun , Nomura Yuichiro , Kitamura Yoshihide
Published: November 2024

DFC and DFC2 subcommittees in the Japan Welding Engineering Society developed a new approach of fatigue analysis method. This fatigue analysis method has been made several modifications and incorporated into the JSME Environmental Fatigue Evaluation Method 2022 Edition (JSME S NF1-2022). Research on effects of surface finishing and mean stress on fatigue lives of notched specimens have been followed by DFC3 and DFC4 subcommittees.

In the DFC4 subcommittee, it was investigated the evaluation method of combined effects of stress concentration and surface finish, and stress concentration and mean stress on the fatigue properties of ferritic steels. DFC4 subcommittee evaluated the load controlled fatigue test results using notched round bar specimens. The fatigue tests were finished when the displacement over notch mouth exceeded the prescribed value and crack depth was measured on the fracture surface of specimens. Although the fatigue lives of specimen should be compared based on the same crack depth, crack depths are different among the specimens when the fatigue test finished. To compare the fatigue lives based on the same standard life among the specimens, the fatigue crack growth analysis was conducted. The stress intensity factor (SIF) of surface crack in notched round bar specimen was investigated first. Next, the suitable fatigue crack growth rate (FCGR) for tested material was investigated among the existing FCGR equations and determined. The crack depth for fatigue life evaluation was determined to be 2 mm and influence of FCGR, stress amplitude and stress concentration factor Kt on N2mm were investigated by case studies.

It was found that the effects of fatigue crack growth rate, stress amplitude and stress concentration factor Kt on the N2mm were relatively smaller for low-alloy steel than carbon steel because the tested stress amplitude were higher for low-alloy steel than carbon steel.
Elastic Properties of Randomly Oriented Fiber-Reinforced Composites Using ANSYS Material Designer
Authors: Graham Luke , Ma Qin
Published: November 2024

Advanced engineering materials such as fiber-reinforced composites are gradually dominating the modern industry and becoming one of the leading engineering materials on the market. Before manufacturing any structure made of these advanced materials, it is often critical to first obtain their elastic properties. Traditional methods for quantifying elastic properties include analytical and experimental methods. Analytical methods may be used to obtain closed-form solutions, but these methods are limited only to specific types of simple problems. Experimental methods may be derived using simple protocols, but the tests can be expensive and time-consuming. Therefore, numerical analysis can be used to obtain the necessary elastic properties of these advanced engineering materials. Starting at release 19.2 in late 2018, ANSYS introduced Material Designer (MD). The MD essentially allows the elastic properties of advanced materials to be estimated more affordably by using numerical simulation. In this study, ANSYS MD is applied to predict the elastic constants for randomly oriented fiber-reinforced composites, including tensile and shear moduli and Poisson’s ratios. The results were compared with existing models in literature and with available experimental data.
Microstructural Evolution and Creep Behavior of T92/HR3C Dissimilar Welds Used in China Plants
Authors: Che Chang , Cong Yu , Yu Jianming , Chen Xinzhong , Wang Hao
Published: November 2024

Creep rupture experiments were conducted at 650°C under different stress conditions (70MPa, 60MPa, 50MPa) on a T92/HR3C welded joint that had been in service for 105 hours. Scanning electron microscopy and optical microscopy were used to observe and quantitatively analyze the microstructure and precipitates of the samples before and after creep rupture, and the hardness distribution of the joint was measured. The results show that the size variation of Laves phases and M23C6 carbides significantly impact the creep failure of the welded joint. With the increase of creep time, the size of Laves phase in fine-grained heat-affected zone (FGHAZ) on T92 side increases. In addition, the rapid coarsening of M23C6 carbide in this area is an important reason for the decrease of creep strength of welded joints. Further EBSD analysis of FGHAZ revealed changes in the microstructure, including grain coarsening and a reduction in GND values, which were important factors contributing to the degradation of T92 FGHAZ performance. After creep rupture, the hardness in the T92 FGHAZ significantly decreased, becoming the region with the lowest hardness in the entire welded joint, ultimately leading to failure and rupture in this area.