bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fitness-for-Service Assessment of Refractory Lined Duct With Hot Spot
Authors: Yoo Eui Jong , Kim Chongmyung , Choi Capjoo 
Published: November 2023

Abstract
The duct line in FCC unit is generally designed using carbon steel with inside refractory lining for a high temperature of service fluid. The refractory could be degraded during operation due to various causes. When the refractory is damaged and a high temperature of service fluid is affected to the duct directly, the surface of the duct is exposed to the elevated temperature, and it is called a hot spot. The temperature increase of hot spot does not lead to immediate failure, but it causes structural rupture or bulging of the duct due to creep in the long term. When hot spot occurs, the steam cooling method is generally used to mitigate the creep damage by spraying the steam onto the hot spot area. In case of extensive hot spot, it is difficult to apply the steam cooling method properly. If hot spot is not controlled by mitigation method, it is necessary to check the fitness-for-service of the duct line and determine the remaining life to prepare the maintenance plan to replace or repair the steel part and refractory lining of the duct line.
In this paper, a case study of fitness-for-service assessment is performed for the refractory lined duct with extensive hot spot in FCC unit. Piping stress analysis is performed to calculate stresses by weight and pressure. And remaining life against creep damage is evaluated with ASME B31.3 Appendix V. And detailed finite element analysis is performed under same condition, and creep life is calculated according to API 579 Part 10 Level 2 Assessment.
Through this process, fitness-for-service assessments for the refractory lined duct with hot spot are compared and its effectiveness is discussed.
Residual Stresses Impact on Fast Fracture Risk - Experimental Evaluation on Vessel Low Alloy Steel Plates
Authors: Louerat Jules , Doremus Luc , Ancelet Olivier , Marie Stephane , Chapuliot Stephane , Dahl Anna 
Published: November 2023

Abstract
Framatome and EDF have launched an important R&D program which aims at evaluating the effective impact of residual stresses on the fracture initiation in the brittle-to-ductile transition regime, on vessel low alloy steel plates including a surface defect.
The test program is designed to allow a direct comparison of the tests results, with and without residual stresses, other factors being equal, to address the impact of the residual stresses in the brittle-to-ductile transition domain. High level of residual stresses of secondary nature have been generated on specimens, at the vicinity of defects, without modifying the local material toughness by avoiding the introduction of significant plastic deformation close to the defect.
Specimens are pre-cracked and tested by 4 points bending. Results show an impact of residual stresses on the fatigue crack growth rate but none on the fracture risk in the transition and upper shelf of the brittle-to-ductile transition. Significant impact is only observed at the lower shelf of the material.
It is shown that local approach using Beremin model clearly catches these results. It also demonstrates that residual stresses can be neglected for fracture assessment analysis in the upper part of the brittle-to-ductile transition for high toughness nuclear vessel low alloy steels.
Applicability of Non-Uniformly Varying the Fin Density of Tandem Finned Cylinders As a Viable Vortex and Noise Suppression Technique
Authors: Alziadeh Mohammed , Mohany Atef 
Published: November 2023

Abstract
This article explores the applicability of using non-uniform finned tubes in tandem arrangement at L/Deq(avg) = 2.5 to suppress flow-induced acoustic resonance. Particle Image Velocimetry (PIV) measurements are performed to visualize the vortex development in the wake before and during flow-induced acoustic resonance. Acoustic pressure measurements are performed to characterize the aeroacoustic response of the tandem finned tubes. It was found that non-uniform finned tubes weaken the vortex shedding process and reduce the sound pressure level (SPL) during flow-induced acoustic resonance associated with the vortex shedding process by 50%. However, non-uniform finned tubes do not hinder the instability of the shear layers within its gap. This makes non-uniform finned tubes susceptible to flow-induced acoustic resonance associated with the instability of the gap shear layers. During this type of acoustic resonance excitation, highly discrete and well-organized vortex cores are formed in the gap and wake of both uniform and nonuniform finned tubes with SPL similar to that generated by the uniform finned tubes. A summary of the results are presented in the paper.
CFD Investigation of Effects of Different Feed Injection Schemes on Reaction Coking in an Industrial RFCC Riser
Authors: Chen Sheng , Yan Zihan , Chen Ming , Liu Mengxi , Liu Juanbo , Xie Guoshan 
Published: November 2023

Abstract
Heavier and poorer crude oils often produce more reaction coke and lower yield of target product such as gasoline and LPG in a commercial FCC riser, and then affect the safety and running period of reactor. Our previous cold-model simulation indicated that a modification from the conventionally upward feed injection scheme to a downward one improves the oil-catalyst mixing. This work aims to improve oil cracking reaction and avoid coking process with a downward feed injection scheme, wherein the feed jets counter-currently impact the catalyst particle flow from riser bottom. A twelve-lump kinetics and vaporization of liquid oil were considered in a multiphase Eulerian model with the energy minimization multi-scale drag and mass model (EMMS). The extent of fixed coke near riser wall was predicted with our fixed coking model in simulation. Comparison with simulation date of upward feed injection scheme is conducted in terms of the profiles of oil gas component and fixed coke and the yields of gasoline and LPG at riser outlet. The results show that the simulation approach can accurately predict the complex processes of gas-liquid-solid three-phase flow, vaporization and reaction coking. Big discrepancies of multiphase flow and mixing occurs in the feed injection zone. The counter-current feed injection scheme can accelerate the vaporization of liquid oil droplets and speed up the heat and mass transfer compared with the traditional upward scheme; moreover, it can also improve the product yields and obviously reduce the deposition of coke near riser wall, especially in the feed injection zone. An optimal feed injection velocity with the counter-current scheme can greatly improve the conversion of raw oil, increase the yield of desired products such as gasoline and LPG, and reduce the amount of coke produced by reaction (19.49%).
A Mechanical Performance Comparison Between GMCL and Hybrid Gaskets
Authors: Abdelgalil Abdelgader 
Published: November 2023

Abstract
The paper provides a mechanical performance comparison between two types of gaskets; the GMCL and the Hybrid gaskets. A nonlinear FEA modeling was used to determine the pressure variations across the gasket face. The models determine pressure distribution on gasket face during installation, followed by gradual increase in pressure and temperature to represent normal operation condition. In all of these stages, the details of: gasket seating, gasket sealing and flange face rotation are all determined and compared.
Reliability and Life Assessment of Coke Drums Through Boat Sample-Based Testing
Authors: Saini Nitin , Lyu Zhe , Suzuk Yasin , Skinner Travis , Ju Feng , Iverson Millar , Bohra Sudeep , Li Leijun 
Published: November 2023

Abstract
Life assessment of coke drums is vital to prevent circumferential through-wall cracking and to ensure it’s safe and serviceable. Cracking in the shell/skirt-shell junction/welds, permanent distortion, and bulging (due to the ratcheting effect) are common damage mechanisms due to low cycle thermal fatigue. The difficulties in performing an insightful inspection and life assessment are limited by the wall thickness, location heterogeneity due to service conditions, and test methods. In this study, a boat sample-based testing procedure is developed for the life assessment of coke drums. The boat samples are extracted from four different locations named crack, bulge, notch, and benchmark from a 40-year serviced coke drum. The boat samples are machined for sub-size smooth tensile, notched tensile, low-cycle fatigue, and Charpy toughness specimens. Smooth tensile, notched tensile and low-cycle fatigue tests are performed at three test temperatures (room temperature, 250°C, and 480°C). The results of sub-size specimens are calibrated to full-size and compared with the knuckle plate (least temperature in the coke drum). The fracture toughness of boat samples is predicted by the Haggag method using the smooth tensile and metallographic results. The boat samples have gained strength but have a reduction in ductility and toughness compared with knuckle plate material. The boat samples have shown a change in the microstructure and hardness. Carbide precipitation is observed on the grain boundaries and within the ferrite grains. This precipitation might have reduced the ductility and toughness.
Evaluation of Cr-Mo Steels Welds Produced by Gas Tungsten Arc Welding With High Silicon Contained Solid Filler Rod to Omit Back Shielding
Authors: Takahashi Atsushi , Isono Shinya , Takauchi Hideaki 
Published: November 2023

Abstract
Where single-sided welding is applied to the fabrication and erection of piping, back shielding by inert gas and its maintenance for the first few layers is required for low alloy steels (LAS), stainless steels (SS) and nonferrous alloys to obtain good weldability and quality of welds.
However, installation and removal of back shielding isolations inside piping for the joint and the adjacent areas to be welded are sometimes impractical due to piping layout and construction sequence such as closure joints. And the unexpected remaining isolations sometimes become concerns for obstructing fluid flow or damaging piping components such as valves and rotating equipment during commissioning or after operation.
To solve the concerns, high silicon (Si) solid filler rod was experimented to SS welding by gas tungsten arc welding (GTAW) to omit back shielding, and positive results of the R&D were introduced in ASME PVP2022 [1]. The same concept using high Si solid filler rod for GTAW was expanded to welding for Cr-Mo steels and properties of the welds were studied by comparison of the welds produced by different concentration of Si in filler rods to the conventional GTAW with back shielding. This paper discusses and evaluates the potential of the GTAW with high Si solid filler rod which can omit the inert gas back shielding for Cr-Mo steels because positive results of the study were obtained as the same as the R&D for SS welds.
The Effect of Loss of Constraint on the Initiation of Ductile Fracture in a Mini-CT
Authors: Li Meng , Chaouadi Rachid , Uytdenhouwen Inge , Pardoen Thomas , Bonny Giovanni 
Published: November 2023

Abstract
As one of the most appealing miniaturized geometries for fracture toughness characterization, the miniature compact tension (mini-CT) geometry was demonstrated to provide reliable fracture toughness measurement in the ductile-to-brittle transition regime and Master Curve assessment. However, when using a mini-CT in the upper shelf (fully ductile) regime, the ductile crack initiation and the crack growth resistance tend to be underestimated for most of the investigated RPV steels.
Previous experimental investigations have attributed the underestimation of the crack resistance properties to two concurrent processes related to loss of constraint and cold working occurring in the ligament ahead of crack tip during cracking, and gave an engineering size correction that mainly accounts for the thickness of the specimens. In this study, finite element simulations and two micromechanics-based approaches: the Rice-Tracey void growth model and Thomason void coalescence model are combined, aimed at investigating the role that the loss of constraint plays in the initiation of ductile fracture in a mini-CT and providing numerical evidence to support the proposal of the size correction on the critical fracture toughness. The final objective of this paper is to estimate the ductile crack initiation behavior that would be obtained from a standard 1T-CT specimen by applying appropriate size correction on a mini-CT.
The results show that the method incorporating the finite element simulations and two micromechanics-based approaches can well describe the effects of loss of constraint for different materials, thus contributing to the size correction of critical fracture toughness of mini-CT in various conditions.
Ventilating Process and Pyrolysis Gas From High-Pressure - Reactor Conditions on Mini-Plant Scale
Authors: Imhoff Moritz , Busch Markus 
Published: November 2023

Abstract
Pressure relief systems for high-pressure applications such as the high-pressure polymerization process are calculated mostly via API 520[1]. Here and in other empirical methods like the DuPont method, the mass relief is calculated via the density of ethene for the given process conditions. The valve body characteristic is further considered. Different physical properties of an unburned and burned phase in the case of a ventilated deflagration are generally not considered. The objective of the presented work is to generate an in-depth understanding and increase the reliability of venting process gases exemplary from the high-pressure polymerization process regarding real scenarios like considering polymer content and pyrolysis products from ethene decomposition. A transient pressure relief model and method is employed with the help of an isentropic nozzle model and a real gas equation of state. Polymerization mixtures are relieved from pressure up to 2000 bar, throughout a defined nozzle diameter. Thermodynamic behavior of gas mixtures is calculated with a real gas equation of state. The ventilation of ethene with a polymer component up to 20 wt.% content does reduce the discharge coefficient in comparison to sole ethen. Still, the resulting depressurization rates are mostly faster due to the higher density of the mixture. When pyrolysis gas from ethene decomposition is ventilated, the increased temperatures from decomposition heat and the resulting products do affect the relief process in a systematic manner. Hereby the depressurization takes longer in comparison to the unburned phase. Calculated discharge coefficients are significantly reduced compared to polymerization mixtures.
Application of the J-Q Methodology to Consider the Geometrical Effect on Fracture for Large Steam-Generator Tubesheet
Authors: Ancelet Olivier , Marie Stephane , Chapuliot Stéphane , Parrot Aurore 
Published: November 2023

Abstract
In the frame of a Fracture Mechanics Assessement in the perforated part of the steam-generator tubesheet, a defect relying two holes is postulated, which represent a singular configuration compared to conventional FMA. Indeed the defect is relatively small in comparison to the plate thickness and the crack length is limited by the distance between two holes.
To take benefit of the geometry effect of this configuration, an application of the two parameters J-Q approach is performed on tubesheet component.
At first, the methodology was applied to define and validate the methodology on an experimental data base with different constraint levels. This data base contains numerous fracture tests performed by both EDF and Framatome on various specimen geometries extracted from a 18MND5 low alloy ferritic steel plate, in the brittle-to-ductile transition regime. C (T), SEN (T), SEN (B), and non-standard specimens [1].
Secondly this methodology is applied to predict the benefits of this approached for tubesheet configuration. Different configurations are tested: underclad defect, surface defect, mechanical loading, thermal shock, in the middle of the perforated zone or near the border of the perforated zone.
These applications show some significant constraint effect for underclad defect and some moderate effect for surface effect.
A methodology is proposed to correct the classical Engineering Fracture Mechanics Assessment to gain margins without considering any probability of failure or statical approach.
Suggested Procedure for Determining the PCC-1 Appendix O Gasket Properties
Authors: Girão Carlos D. , Veiga José C. , Meira Igor 
Published: November 2023

Abstract
The ASME Pressure Vessel and Boiler Code Section VIII – Appendix 2 – Rules for Bolted Flange Connections with Ring Type Joints [1] has been used successfully for many years. An experienced engineer will apply the rules and, in most cases, the vessel will be operated for many years without leakage. However, there have been many papers addressing its shortcomings [2–4]. The Gasket Properties of the Appendix 2 has never been updated with newer designs and materials. Its tabulated values are reminiscent of the “Asbestos time”. Properties such us maximum gasket stress and relaxation are not considered.
The ASME – PCC-1 – Pressure Boundary Bolted Flange Joint Assembly [5] has introduced the Appendix 0 – Assembly Bolt Stress Determination to address some of the problems associated with the Appendix 2. Several new gasket properties were introduced without a procedure to determine them. Two papers presented at PVP Conferences [6,7] proposed a protocol to determine some of the gasket properties.
In Europe the rules for calculating flanges and determining the gasket properties were updated with the EN 1591 - Flanges and their joints - Design rules for gasketed circular flange connections [8] and EN 13555 - Flanges and their joints – Gasket parameters and test procedures relevant to the design rules for gasketed circular flange connections [9]. Since their introduction there has been a major effort to test gaskets and determine their properties. Manufactures are publishing results and there are two public websites [10,11] where values are posted. With so many data available the purpose of this paper is to suggest a procedure to use the EN13555 data to determine the Appendix – O gasket properties.
Study on the Circumferential Pressure Distribution of the Tube Bundle in the Center of the Heat Exchanger
Authors: Qi Sijiu , Tan Wei , Zhu Guihong , Zhu Guorui 
Published: November 2023

Abstract
The fluidic vibration problem of heat exchanger tube bundle is an important factor causing its destruction. In this paper, a combination of experimental and numerical simulations is used to study the pressure distribution and inter-tube flow field on the central tube bundle of heat exchangers at low flow velocity, and to provide data support and theoretical support for the vibration analysis of the tube bundle.
Based on the computational fluid dynamics method, ANSYS Fluent software was used to perform numerical simulations for four types of arrangement: square triangle, square, corner triangle and corner square models with different incoming flow velocities and pitch ratios. The calculation results show that the stationary point of the central tube varies in position and number with the change of flow velocity at low flow velocity, and gradually stabilizes after the flow velocity increases. It is also observed that the standing point of the central tube gradually moves backward with the increase of the incoming flow velocity. The angular size of the boundary layer separation point: the angle of the corner triangle arrangement is the largest, the angle of the square triangle arrangement and the square arrangement is the second largest, and the angle of the corner square arrangement is the smallest; there is no significant change in the size of the pressure in the direction of incoming flow for different pitch ratios of the central tube, and the position of the standing point remains basically the same, but the pressure in the direction of the wake flow decreases slightly with the increase of the pitch ratio.
To verify the simulation results, a water-tunnel experimental setup was designed to measure the pressure distribution around the circumference of the tube bundle using an electronic pressure scanning valve. The experiments verified the vibration characteristics in the environment of a tube bundle arranged in a square triangle with a spacing ratio of 1.41, which is consistent with the trend of the simulation results and verifies the reliability of the simulation results.
Investigation of Acoustic Resonance Phenomenon in a Large-Scale Heat Exchanger
Authors: Huang Guofeng , Wang Heng , Tan Wei 
Published: November 2023

Abstract
In gas-gas heat exchangers, pure tone noise can be generated by gas flow pass tube arrays when the frequency of vortex shedding is close to that of acoustic modes, which is called acoustic resonance. Such resonance phenomenon usually occurred while serving because it is difficult to predict in the design stage. The loud noise is harmful to operational staff and may cause structural damage. The paper reports a case of acoustic resonance in a large-scale heat exchanger containing more than 15,000 staggered tubes with a pitch ratio of 1.33. Unexpected acoustic resonance occurs during service although two longitudinal baffles have been installed aiming to eliminate it. The noise of high-pressure levels appears in the heat exchanger operation process. Acceleration signals are obtained at different positions of the outer wall. Results show that acceleration fluctuations are dominated by narrow band peaks from 100 to 145Hz. By numerically investigating the characteristics of the flow field, vortex shedding frequency is found to be similar to this range, indicating a close relationship between vortex shedding and acoustic resonance. The acoustic modes of the shell side are also calculated by using the effective speed of sound. The results show that the modes excited are more likely to be a combination of longitudinal and transverse modes, rather than a transverse mode which is more commonly encountered. Longitudinal modes used to be ignored and staggered tube bundles are considered not prone to suffer acoustic resonance, which may increase the risk in the design stage. From the case discussed in this paper, it is probably necessary to take both longitudinal and transverse coupled modes into consideration.