bluuebunny/crossref_metadata_2025_split huggingface dataset:
Validity of Toughness Measurements From Miniature Specimens Failing in Different Fracture Modes
Authors: Ortner Susan , Sanchez Marcos , Echols John , Cicero Sergio , Chekhonin Paul 
Published: November 2024

Abstract
Using 0.16T (4 mm thick) compact tension specimens to determine toughness in reactor pressure vessel steels permits the ductile to brittle transition temperature to be derived from small amounts of material and allows more effective use of surveillance specimens. Achieving validity in the toughness measurements requires more care in specimen manufacture, load train alignment and test temperature selection than when larger specimens are used. This is particularly evident in the shapes of precrack fronts, which appear more sharply asymmetric on smaller specimens. Questions have also been raised as to whether the failure mechanisms are the same in miniature and large specimens. This work, performed within the FRACTESUS project, presents toughness measurements and detailed fractography on both a homogeneously brittle base metal and a relatively ductile, inhomogeneous weld. The fractography shows that, even in a ductile weld metal exhibiting clear shear lip, brittle fracture initiates within the part of specimen experiencing small scale yielding, so long as the toughness measurement is valid. Similarly, although the precrack front asymmetry appears more marked in smaller specimens, as long as the deviation from planarity is within the ASTM limits, the asymmetry does not affect the location of the initiation site. For materials showing a variety of fracture modes, the fracture modes observed at the initiation sites are consistent with those observed in larger specimens. Where data are available, the stress and strain conditions at the initiation sites are also found to be consistent in 0.16T and larger specimens. These fractographic observations support the thesis that toughness measurements made on miniature compact tension specimens reflect the same material characteristics and failure mechanisms as those on larger specimens. The limitations on specimen geometry and loading identified by the ASTM Standard are sufficient to ensure that transition temperature values derived from miniature compact specimens are valid for materials failing via a variety of fracture modes.
Stress Analysis of Explosion-Welded Stainless Steel to Aluminum Cryogenic Transition Joints
Authors: Ok Ali 
Published: November 2024

Abstract
Transition joints are commonly used to connect components built from two dissimilar metals. In cryogenic applications, aluminum to stainless steel transition joints are often used to connect aluminum vessels and heat exchangers to stainless steel piping. Such transition joints have been built using different technologies. In this paper, explosion-welded transition joints will be considered and modeled.
All piping transition joints must be designed to accommodate stresses due to pressure and other piping loads and forces. Explosion-welded stainless steel to aluminum cryogenic transition joints typically utilize multiple intermediate material layers for better bonding (depending on the manufacturer’s process) and to accommodate the differential thermal expansion/contraction between the aluminum and stainless steel outer layers. Considering aluminum alloys have thermal expansion coefficient approximately twice those for steels, consideration shall be given to the operating temperature of the joint to evaluate the thermal stresses occurring at the interlayers.
ASME PVP2023-105205 paper discusses the qualification methods and requirements for explosion-welded parent plate and transition joint design but the thermal stress effect on the transition joints due to the differential thermal expansion/contraction in the materials was not discussed in the paper. This paper includes thermal stresses occurring on the joint due to the differential thermal expansion/contraction and its impact on transition joint design. Finite Element Analysis (FEA) is used to understand the effect of the joint geometry and material composition on internal stresses due to the combination of pressure, piping loads, and differential thermal expansion/contraction within the joint.
Expanded PTFE Gasket Material Performance Variation With Thickness
Authors: Bausman Anita , Wilson Jeffery 
Published: November 2024

Abstract
Polytetrafluoroethylene (PTFE) is an excellent gasket material, chemically, but it has relatively poor mechanical performance. As a result, much effort has gone into improving the mechanical performance of PTFE-based gasket materials. Methods to improve mechanical performance include the addition of fillers (glass fibers, glass microspheres, silica, barium sulfate, carbon, etc.) and the manipulation of the microstructure (micro-cellular, expanded, restructured, etc.). These various forms of PTFE materials can have widely varying mechanical performance. PTFE materials that are chemically the same will have significantly different mechanical performance if the manufacturing process and microstructure are different. An example is the performance of amorphous, virgin PTFE sheet compared to the performance of fibrillated, expanded PTFE (ePTFE) sheet. The thickness of a gasket material is another structural difference that results in different mechanical performance.
This paper is an extension of PVP2022-84765, PTFE Gasket Material Performance Variation with Thickness [1], which investigated barium sulfate filled, restructured PTFE’s mechanical performance. This paper explores the difference in the mechanical performance of common expanded PTFE (ePTFE) materials that are often considered to be functionally the same by end users. The mechanical performance of each material is compared for different thicknesses using the Hot Blowout, Thermal Cycling test (HOBTC, ASTM WK61856 Rev 10-9-2020). [2] The authors selected these thicknesses for performance review because of their usage in industry. ePTFE sheet is most commonly used on vessel and equipment flanges. The thinner thicknesses considered in this paper, 1.5 mm (1/16 inch), is most commonly used in piping flanges. The two thicker sizes reviewed for this paper are 3 mm (1/8 inch) and 6 mm (1/4 inch). Because ePTFE is so conformable, it is often used on problematic flanges with irregularities in the flange faces. Hence, the 6 mm (1/4 inch) thickness is more commonly seen with ePTFE applications than with other forms of sheet PTFE gasketing. Very little test data on 6 mm (1/4 inch) thick ePTFE exists. Leakage testing is according to the Room Temperature Tightness test (ROTT, ASTM F2836) [3]. The authors primarily used lab tests for HOBTC and ROTT data with some comparison to publicly available data. HOBTC and ROTT lab tests were performed on an amtec TEMES fl.ai1 test fixture at the authors’ company. This data will demonstrate to the end-user how different the mechanical behavior can be of the same ePTFE gasket material whose only obvious difference is how thick it is.
Analysis and Treatment of Pipeline Vibration Driven by Turbine-Driven Boiler Feed Water Pump
Authors: Wang Chengwen 
Published: November 2024

Abstract
Boiler feed pumps in thermal power plants are normally powered by electric motors, but turbine-driven pumps are also used to reduce operating costs.
However, during the first startup phase, a steam-driven boiler feed pump pipeline encountered unexpected serious vibration. The vibration gradually worsened as the turbine speed rised during the acceleration stage to the rated speed of 3000 rpm. The entire concrete floor kept vibrating due to the severe vibration of the pump inlet pipeline, even with reinforced support. It had been discovered through a series of vibration measurements that the pressure control valve in the reflux pipeline, which has a labyrinth pressure reduction construction, was the primary cause of the vibration. Resonance was brought on by the pressure drop waves that travelled through the fluid and had an impact on the pump’s intake and exit pipelines. Furthermore, the vibration frequency didn’t change with speed, showing frequency locking. When the swing check valve of the pump outlet pipeline was opened normally and the return pipeline was no longer working, the entire system returned to normal. In order to achieve this goal and ensure the construction progress, viscous dampers were added to the pipeline system to absorb vibration, allowing the pump to smoothly reach the rated speed.
Expanded PTFE Gasket Material Performance Variation Comparing Solid to Jointed Constructions
Authors: Bausman Anita , Wilson Jeff 
Published: November 2024

Abstract
Polytetrafluoroethylene (PTFE) is an excellent gasket material. Expanded PTFE (ePTFE) achieves better mechanical performance compared to plain PTFE by a highly fibrillated microstructure. However, between the fibers of the ePTFE, there are air voids. To achieve superior sealing, the microstructure must be adequately compressed to close these voids and reduce permeation leakage through the gasket material itself. During this compression, the ePTFE dimensions shrink in contrast to most PTFE sheet materials that radially expand when compressed. This ePTFE behavior is problematic where a gasket with a joint is needed, for example on industrial column body flanges larger than available ePTFE sheets. Care must be taken to make a leak-free ePTFE joint on such gaskets.
Industry experience with the common dovetail joint has been poor using ePTFE materials. However, joints are sometimes needed. The authors investigated the leakage and mechanical performance of ePTFEs as solid rings without joints, industry-standard dovetail jointed rings, and Engineered Interference Tortuous Path (EITP) jointed rings. Data was collected according to the EN13555 leakage test at room temperature [1]. A preliminary investigation of pressure performance at temperature was made using the first step of the Hot Blowout Thermal Cycling (HOBTC, ASTM WK61856 Rev 10-9-2020) test (no thermal cycles this test round) [2]. Lab tests were performed on an amtec TEMES fl.ai1 test fixture at the authors’ company.
Tensile Strain Capacity of an X70 Pipe With Internal and External Semi-Elliptical Crack Under Bending and Tension
Authors: Yu Xinping , Park Dong-Yeob , Wang Xin 
Published: November 2024

Abstract
This paper studies an in-depth examination of the tensile strain capacity (TSC) of an X70 pipeline containing an internal or external semi-elliptical crack when exposed to bending or tension. Comprehensive TSC evaluations were conducted through finite element analyses, incorporating initiation and ductile tearing criteria for different crack depths and magnitudes of internal pressure. During the analyses, crack-tip opening displacement (CTOD) and J-integral were calculated, taking into account the crack’s depth and the magnitude of the internal pressure. The finite element results enabled a precise estimation of crack driving forces for both CTOD and J-integral, with respect to the remote strain of the pipeline. The findings revealed that, in bending scenarios, both internal and external cracks exhibited lower values of CTOD and J-integral compared to tension conditions, resulting in a slightly higher tensile strain capacity. The disparities observed in CTOD and J-integral values between bending and tension conditions were relatively minor, suggesting that material and pipe properties may exert a more pronounced influence on their behavior than the specific loading condition in the pipeline. TSC calculations using initiation and ductile tearing methods indicated no significant differences for either external or internal cracks, under both bending and tension conditions. This study provides valuable insights into the TSC assessment of full-scale pipelines with semi-elliptical cracks, highlighting the significance of considering the specific loading conditions in such evaluations.
Indicators for Coke Drum Replacement Due to Bulge-Induced Damage
Authors: Araque Vivas Egler Dubin , Park Stephen Michael 
Published: November 2024

Abstract
Replacement of coke drums is a major project that requires a significant investment and at least 3 or 4 years of planning. One of the leading causes of drum replacement has been the cost associated with repairs and unexpected shutdowns due to bulge-induced damage. An assessment of the total area of bulge-induced damage in 10 coke drums from two refineries (Sites A and B) that are conducting replacement projects is shown as an example of parameters that can be identified and tracked over the life span of the vessel.
The Local Plastic Strain Indicator, abbreviated as LPSI, is used as a methodology to quantify and track the evolution of bulged areas and surface damage found during laser mapping and remote visual inspections. LPSI identifies and ranks bulges prone to local failures using plastic strain calibrated against bulges that developed internal or external bulge-induced damage. The LPSI is the ratio of the plastic strain found at the point being analyzed to the calibrated strain limit found at points where through-wall cracks occurred due to bulging, in a percentage form.
Using LPSI to find the surface area of the drum cylinder that is bulged is a novel concept. Results show how total bulged area and the area with elephant skin surface damage increases over time, reaching the point where repairs are required to stop bulge growth and maintain safe operations. Eventually the accumulated bulging, surface damage, and amount of repairs required reach the point where the cost and potential for unexpected shutdowns leads to vessel replacement. Examples are provided to assist refiners in understanding how to assess their own drums.
A Finite Element Method to Simulate Non-Destructive Evaluation Testing of Downhole Tools Subject to Shock and Random Vibration
Authors: Ghosh Pritha , Sisak Ryan 
Published: November 2024

Abstract
A downhole tool typically encounters shock and vibration under different circumstances, including tool handling, tool transportation and tool operation. The aim of this work is to present a finite element analysis (FEA) method that can simulate non-destructive evaluation tests conducted on downhole tools subject to shock and random vibration. The downhole tool assembly is rigged up to the vibration test table and subjected to a shock signal or a random vibration signal as expected in well conditions. A corresponding three-dimensional finite element model of a downhole tool is developed with component geometry details and relevant interactions between the components, accounting for inertia of components and structural material properties. The method involves a two-part analysis of the finite element model: response spectrum and transient dynamic analysis for shock and random vibration. This simulation predicts the mechanical response of the tool used to determine failure within its operating range. The unique contribution of this work is that the analysis approach can capture the effects of the response of the tool assembly similar to non-destructive shock and random vibration testing. Comparisons of frequency response tests and structural integrity inspection from simulations versus testing on the downhole tool establish the fidelity of the FEA method as well as additional insights to the load path of the inner components of the tool assembly. The FEA method thus provides an alternative digital identification of the potential failure under shock and random vibration in downhole tool assemblies that is cost-effective and time-efficient, to reveal potential structural integrity issues of downhole tools in early design stages and identify critical components in the tools that need to be monitored during their physical testing.
Discussion on the Design Life and Ultimate Service Life Determination Criteria of Pressure Vessels in China
Authors: Chen Xuedong , Fan Zhichao , Xu Shuangqing , Chen Wei , Dong Jie 
Published: November 2024

Abstract
China is a big user of pressure vessels, with more than 4.97 million stationary pressure vessels in service by the end of 2022, among which pressure vessels in the process industry with high cost, many consumables, high technical difficulties, long production and procurement cycles. Therefore, the need for their long-term service is urgent. The design life of pressure vessels is the intended use time determined by the designer according to the design conditions and construction specifications to maintain the structural integrity or target function, and is a key parameter to balance safety and economy. The service life of the pressure vessels is the actual service time to maintain the structural integrity or target function under the actual service conditions, and changes with the actual service conditions. Reasonably extending the service life of pressure vessels in use is one of the important tasks of coordinating safety and development.
A Continuum Damage Coupled Unified Constitutive Model for Creep-Fatigue Damage Evaluation of Modified Grade 91 Tube Sheet Structures Under Flexible Loading Conditions
Authors: Islam Nazrul , Hossain Md. Sumon 
Published: November 2024

Abstract
The Grade 91 tube-sheet structure is a critical integral part of Sodium Fast Reactors (SFR) developed by the Japan Atomic Energy Agency. Life evaluation of such a component is complex because of its geometry with the numerous holes and combined creep-fatigue loading conditions at elevated temperatures. The Sodium in the SFR tube sheets is flowed at the operating temperature varied from 650°C and 250°C for hot and cold transients. For these components, the creep-fatigue damage evaluation is commonly performed using simplified approaches such as the Stress Redistribution Locus (SRL) method or non-unified constitutive models where creep and plastic strains are not coupled. However, understanding the behavior of Grade 91 steel under fatigue, creep and creep-fatigue loading conditions and its constitutive model based on these phenomena are important to properly predict the component responses. Hence, this study developed a 3D FE model of the tube-sheet component, utilized the advanced damage coupled unified constitutive model (UCM-CDM) of Mod. Grade 91, formulated by the author earlier, to analyze the creep-fatigue strength of the tube sheet under combined flexible loading. The damage estimation using the UCM-CDM model is compared with other commonly used non-unified models, and the robustness of the UCM-CDM model is discussed.
The Effects of Model Thickness on the Variation of Localised Stress Fields in Four-Point Bending Tests: A CPFE Study
Authors: Kuo Brandon , Taherijam Masoud , Abdolvand Hamidreza 
Published: November 2024

Abstract
Hydrogen embrittlement is one of the principal mechanisms leading to the degradation of engineering materials used in the core of nuclear reactors. This mechanism plays a major role in deciding when to replace the Zr-2.5Nb pressure tubes used in the core of CANDU nuclear reactors. The presence of localised stress fields in CANDU pressure tubes affects the diffusion of hydrogen atoms toward cracks, scratches, and other imperfections. These high-stress regions, in which the hydrogen accumulates, serve as the nucleation sites for hydrides. In this study, an in-house crystal plasticity finite element model was used to study the effects of model thicknesses on the distribution of stresses. This was done to provide a road map for comparing the results obtained from electron backscatter diffraction measurements (EBSD) to those calculated by CPFE modelling. It is shown, that within the ROI, the variation of von Mises stresses changes significantly with model thickness, while the hoop and hydrostatic stresses are only slightly affected. In all cases, the hydrostatic stresses were more pronounced at the midpoint of the sample. Additionally, it was found that to minimise the impact of the boundary conditions on the stresses at the free surface a thickness of 500 μm was found to be optimal.
ASME CC N-900 Revision Discussion (No.2) Revisit of Fabrication Strain Limitation of Pipe Fittings
Authors: Shibukuwa Kenichi , Wen Jie , Takanashi Masahiro , Funasaki Kenji 
Published: November 2024

Abstract
In 2019, ASME Section III and JSME published a remarkable code case (ASME CC N-900[1]/JSME NC1 CC-008[2]) regarding seismic design codes for piping by using elastic-plastic analysis. As shown in PVP2023-107170[3] “Seismic Design Method of Crossover Piping Across Building Isolation Boundary”, while it would be clear that this code case using elastic-plastic analysis allows for a reasonable seismic design of the piping, there are few examples of actual seismic design work using this code case. The reasons why the seismic evaluation method based on elastic-plastic analysis of piping has not been widely applied to actual design works include the limited applicability (especially, fabrication strain limitation of pipe fittings) of ASME CC N-900.
In this paper, a review of the fabrication strain limits for pipe fittings has been performed, and it is reported that the residual strain in the fabrication process of pipe fittings is small and has little effect on the ductility and fatigue strength of pipe fittings.
Mechanical Responses and Assessment of Fatigue Life for Submarine Suspended Pipelines
Authors: Zhang Yi , Shuai Jian , Shuai Yi , Liu Qianqian , Lv Zhiyang , Shi Lei , Jiang Lumeng , Jiang Yuanliang 
Published: November 2024

Abstract
As an essential component for the transportation of oceanic oil and gas supplies, it is crucial to ensure the efficient operation of submarine pipelines. The fatigue failure of submarine pipelines occurs frequently under the combined effects of currents, waves and soil. Firstly, a pipe-soil interaction suspended pipeline model was developed, which could be used to simulate the mechanical behavior of pipes and the dynamic response of the combined loads of waves and currents. Then, the effects of soil properties, current direction and suspended length on the stress distribution and dynamic mechanical response of submarine suspended pipelines were investigated. In addition, the vibration characteristics of suspended pipelines affected by soil were revealed. At last, according to the vortex-induced resonance evaluation and fatigue life assessment method, the critical length of suspended pipelines for the Bohai sea was determined. The results show that the stress change in the center of the suspended section reaches the most significant for the pipeline with a length of less than 20m. When the suspended length exceeds 20m of the pipeline, the connection between the suspended section and the buried section shows the most dramatic stress fluctuations. Meanwhile, the cumulative damage of the submarine suspended pipeline entering the soil becomes the maximum, and fatigue failure often occurs in this position. The results are expected to provide an important theoretical basis in safe operation and repair decision of submarine pipeline.