bluuebunny/crossref_metadata_2025_split huggingface dataset:
Parametric Study on the Vibration of Small-Bore Piping Branch Connections
Authors: van Zyl Gys , Brodzinsky Richard 
Published: November 2022

Abstract
In vibration service, small-bore piping connections, especially unsupported cantilever configurations, are associated with a high level of concern as potential fatigue crack initiation locations. Various international guidelines and procedures address the assessment of piping vibration in general and of small-bore connections in particular. In this work, a review of these guidelines as applied to a specific class of small-bore connection was performed by means of a finite element parametric study on a large number of branch connections. The small-bore configuration evaluated in this work is an unsupported cantilever connection made using an integrally reinforced forged branch fitting with butt-welded joints. At the end of the branch is a flanged connection with either a blind flange only, or a single or double valve with a blind flange. For the parametric study a random distribution of run pipe diameter and thickness and branch pipe diameter, thickness, and length was used to evaluate a few thousand different small-bore configurations. Modal analysis was used to determine the relationship between stress and velocity at two critical locations: the weld between the branch fitting and header and the weld between the branch pipe and branch fitting. Results of the parametric study were processed and compared to the evaluation criteria of a number of established and upcoming guidelines and standards.
Development of Life Estimation Method for Nozzle Welds in Large Scale Piping of Modified 9Cr-1Mo Steel -Part II: Analytical Study
Authors: Takahashi Yukio , Shigeyama Haruhisa , Yaguchi Masatsugu 
Published: November 2022

Abstract
Creep strength-enhanced ferritic (CSEF) steels are widely used in fossil power plants operated in many countries and life management for the components made of these materials are of critical importance for plant operators. In particular, failures in welded joints in softened heat affected zone (HAZ) categorized as type IV failure have taken place widely in piping and boiler headers and prediction of such failure became a urgent requirement to be addressed. Following the simple longitudinal welds, weldments used for attaching various nozzles to main piping or boiler headers became the portions susceptible to type IV failure, stimulating the needs for prediction of their lives also. As a result, it turned out that a more sophisticated approach which can deal with complicated geometries involved in these weldments needs to be developed.
With such a background, the authors carried out an internal pressure creep test at 650 °C using the pipe of P91 steel with the outer diameter of 457.2 mm. Outline of testing condition as well as the results including the periodic damage inspection by several methods is presented in the accompanying paper whereas related analytical efforts will be described in this paper. Detailed finite element analyses were performed on nozzles with different geometries, incorporating creep deformation properties of each continuant of welded joint. Moreover, failure criterion based on inelastic strain energy density has been developed for softened HAZ, taking into account of the dependency on temperature, creep strain rate as well as stress triaxiality factor. Results obtained using these properties were compared with the test results in terms of the location and extent of cracking due to creep damage accumulation. They showed reasonable agreement, demonstrating the soundness of the developed approach.
Analysis on the Evolution Process of Dynamic Performance of Single Bolt Connection
Authors: Zheng Mingpo , Liu Zhifeng , Yan Xing , Chen Wentao , Li Ming 
Published: November 2022

Abstract
The connection quality of the bolted joints directly determines the service performance and reliability of the structure. However, there will always be a certain degree of loss in the bolt clamping force during the long-term service, accompanied by degradation of the mechanical performance. Herein, the experimental study on the single bolt connection was carried out to analyze the evolution process of dynamic performance. The clamping force was continuously monitored after tightening to obtain a quantitative analysis of its loss with and without external loads. The loosening curves of the clamping force with the service time was established respectively considering the main influencing factors. Transverse cyclic loads were applied to obtain the service loosening data of the bolt clamping force. The dynamic performance characterization parameters of the structure under different clamping forces were obtained through the modal test. On the basis of established force-performance relationship, the service conditions of the connection structure were evaluated to propose a performance evolution equation that varies over time. A comprehensive understanding of the service and evolution process of bolted joint was obtained through the experiment and analysis in this work. It provides an important reference significance in the performance prediction and control of bolted joints, which can help design a more reasonable structure.
New Evaluation Method for Seismic Fatigue Damage of Plant Pipeline (Quantitative Performance and Consideration of Application)
Authors: Inada Fumio , Sakai Michiya , Morita Ryo , Tamura Ichiro 
Published: November 2022

Abstract
In previous reports, it was shown that the cumulative absolute velocity (CAV) for each wave of the pipe seismic response corresponds to the vibration stress amplitude. A new seismic fatigue evaluation method was proposed by applying this relationship to Miner’s law of material fatigue damage. As a result, the cumulative fatigue damage can be calculated in proportion to the CAV of each wave to the power of 2.4. In this study, how the new method can be used to evaluate the cumulative fatigue damage quantitatively is considered. The cumulative fatigue damage was evaluated by the rain flow method as well as the new method where the parameters showing the effect of the concentrated mass and the pipe configuration on the vibration stress-velocity relationship were calculated accurately using the precisely analyzed mode function. The two results were found to be in good agreement. It is considered that this new method can give the evaluation result that envelops the pipes of the entire plant by appropriately setting the parameters.
High Pressure Connections Bolt Tightening – Requirements, Challenges, Problems, and Solution Proposition
Authors: Lutkiewicz Przemyslaw , Kirkemo Finn , Robertson David 
Published: November 2022

Abstract
There are many International and National standards for flanges and clamp connections. Different bolt pretension values are required by these standards. In general, two bolt tightening methods are recognized: by torque or tension tools. The tensioning method is more accurate; however, this requires temporary higher pretension. ISO-27509, for example will need temporary bolt pretension equivalent to 90–95% of yield strength, API 6A allows up to 83% of bolt yield strength. Metric and Imperial bolting types can be used. Both types have related thread standards with specific tolerance classes. It is known from field experience that in some cases combination of thread tolerances, bolt size, and tightening with tension tool, the induced interference between the nut and stud threads can prevent the turning of the nut preventing the correct pre-load. This paper investigates the problem and proposes some solutions to avoid jamming. Paper will present general overview and deep problem investigation based on Finite Elements nonlinear analysis results. The requirement for smooth nut turning thread clearance will be calculated. The thread tolerances will be compared and investigated in light of existing standards and beyond. The threads load carrying capacities will be also addressed in light of analytical calculations. The thread stripping phenomena will be also addressed. In addition, the torque tool method will be discussed in term of bolt stress and accuracy. The bolt scatter will be included in the discussion.
Constraint Effect on Fracture in Ductile-Brittle Transition Temperature Region (Report 2)
Authors: Hojo Kiminobu , Hirota Takatoshi , Nagoshi Yasuto , Fukahori Takuya , Sakima Kimihisa , Ohata Mitsuru , Minami Fumiyoshi 
Published: November 2022

Abstract
In order to predict fracture behavior of a structure with low constraint, tensile fracture tests using flat plate specimens with a surface flaw were performed at −80°C and −120°C in the ductile-brittle transition temperature (DBTT) region. The shape of the flat plate was 50mm thickness, 200mm width, and 500mm length. A semi-elliptical flaw of 5mm depth and 25mm length was introduced on the specimen’s surface. The measured KJ at fracture of the flat plate specimens were located between the predicted fracture probability bound of 5% and 95% of KJc from the laboratory specimen, C(T) and SE(B), including those for bending load obtained in the previous paper of the PVP2021 conference, Report 1. The Weibull parameters of the Weibull stress, m and σu, for the Beremin model and the parameters of the GTN model from the laboratory specimens, SE(B) and C(T) specimens, were used for the fracture probability prediction. Based on this verification result of the prediction procedure using the coupled model of the Beremin model and the GTN model, the plastic constraint correction coefficient χ, was proposed for fracture evaluation of a reactor pressure vessel. For simplification of the fracture evaluation, uniaxial loading plate models which accurately simulate the mechanical behavior of a reactor pressure vessel for representative PTS transients were applied for calculation of the coefficient χ.
The Development of a New Method to Compare the Fatigue Crack Growth Rates of Austenitic Stainless Steel Operating in a PWR Primary Coolant Subjected to Plant Realistic Temperature Loading
Authors: Howe Benjamin , Scenini Fabio , Burke Grace , Mann Jonathan 
Published: November 2022

Abstract
Fatigue Crack Growth Rates (FCGRs) of austenitic stainless steels can be significantly enhanced when tested in a high temperature water environment compared to those tested in air. Existing FCGR models are based on simple isothermal waveform loading. Recent work has highlighted that there may be a potential benefit into taking account of plant realistic loading waveforms in fatigue assessments as these may be less damaging than predictions based on simple loading conditions. As a result, new methods to account for these plant realistic loads have been developed to reduce excess conservatism of existing methods for predicting FCGRs.
To provide confidence in these methods, a previous UK thermomechanical fatigue testing programme has been conducted on Compact Tension (C(T)) specimens subjected to plant realistic loads, with the crack length and Crack Growth Rates (CGRs) being monitored in-situ using the Direct Current Potential Drop (DCPD) technique. This paper utilizes three different methodologies to evaluate the CGR of samples that underwent corrosion fatigue in different conditions namely; DCPD, post-mortem measurement of crack advance using Scanning Electron Microscopy (SEM), and the measurement of the spacing between striations to infer CGR.
It was found that DCPD provided a good global average of FCGRs at the crack front but does not capture local changes associated with the local microstructure.
Overall, it was shown that post-mortem examination for stage measurements can be reliably applied to infer CGR on samples that were not instrumented with DCPD.
Simulation of Compression Set of EPDM O-Rings During Aging
Authors: Zaghdoudi Maha , Weber Mike , Kömmling Anja , Jaunich Matthias , Wolff Dietmar 
Published: November 2022

Abstract
It is common practice in the application of finite element analysis to model compression set (CS) of elastomers during aging with two different material models according to the two-network theory of Tobolsky. The theory relies on the existence of two networks. The first one represents the original network after vulcanization and is sensitive to chain scission. The second network accounts for the formation of additional crosslinking during aging. Besides the use of user subroutines to describe the two-network model, an element overlay technique is also needed as the full set of both material behaviors did not exist for assignment to a single element. This element overlay technique is valuable for research and developmental purposes but makes extension to industrial usage quite challenging. Our goal is to simulate the CS of elastomers after long-term aging in a commercial finite element software with no need for extra subroutine codes or mesh superposition.
Ethylene propylene diene (EPDM) O-rings were aged in a compressed state at 75 °C, 100 °C, 125 °C and 150 °C for up to 183 days. Investigations of the experimental test results were used to identify material models and their parameters to develop a finite element model to simulate CS. The model was implemented in the finite element software ABAQUS/Standard® with a sequential temperature-displacement coupling.
Regarding the influence of temperature, the Arrhenius equation is adopted for the time-temperature relationship. The activation energy value that is required for the simulation is firstly determined from shifting the experimental CS results with the time-temperature superposition technique and plotting the shift factors in an Arrhenius diagram. The experiments were compared with the simulation results. Afterwards different activation energies were used in the simulation and discussed. A suitable choice of the activation energy value with regard to the reference temperature and the test temperature is presented. With the chosen activation energies, the match between numerical CS values after long-term aging and the experimental results was improved.
Plan of a Shaking Table Test on a Piping System Model for Verifying the Fracture-Control Concept
Authors: Nakamura Izumi , Kasahara Naoto 
Published: November 2022

Abstract
To mitigate the severe effects in the beyond design basis accident (BDBA), the concept of fracture control was proposed in the previous study. The idea of the fracture control is to manage the accident consequence by controlling to cause minor failure prior to the fatal failure.
Taking the piping system as an example, boundary failure should be prevented under the BDBA condition, whereas the minor failure, such as support failure which does not affect the function of the piping system, can be acceptable.
To realize the fracture control concept on piping system, shaking table tests on piping systems with support are planned. As the first step of the attempt, fundamental experiment on relatively simple piping system and support configuration was conducted. In this experiment, pipe elbows made of simulation material (lead-antimony alloy) were used, and the support was modeled by a plate. Through the experiments, the fracture of support successfully occurred prior to the large deformation of pipe itself. The results showed that the fracture control may be possible when the fracture of support occurred prior to the failure of pipe itself, and the ratio of the input frequency to the specimen’s natural frequency (fR) be over 1.0 after the support failure. The test results demonstrated the possibility of fracture control concept by support failure.
As the next step of the attempt, shaking table test on more realistic piping system, which is named as validation test, is now prepared. The preliminary analysis shows that the inelastic behavior of support is expected.
Assessment of Gaseous Detonations in Pressure Vessels
Authors: Pease Derrick , Abatt George , Clutter Keith 
Published: November 2022

Abstract
This paper covers several practical engineering aspects of gaseous detonations in pressure vessels: (1) Description of the phenomena and physics of deflagration, detonation, deflagration-to-detonation transition, and reflections in pressure vessels; (2) Development of pressures and loads caused by the detonation process in pressure vessels; (3) Analytical evaluation techniques and assessment criteria in the context of the ASME B&PV Code Section VIII. There are many factors that govern the type and severity of gaseous detonations in pressure vessels including gas composition, initial pressure, and ignition location within the pressure vessel. This paper addresses several of these factors, how they affect the resulting pressure transients in the vessels, and how the pressure transient loads can be applied to the Abaqus structural model. The method of load application is easily adapted to other FEA software packages. The structural integrity of the vessel is evaluated using the Abaqus Johnson-Cook plasticity model and associated strain limit damage criterion. The paper is specifically focused on pressure vessels where gaseous detonations have unique characteristics compared with more constrained space such as piping systems. A companion paper (PVP2022-84291) addresses the unique characteristics of gaseous detonations in piping systems and pipelines.
An Evaluation of Probabilistic Integrity Assessment Codes
Authors: Guo Lingyun , Niffenegger Markus 
Published: November 2022

Abstract
In recent years, a large number of failure assessment models (FAMs), like SINTAP, BS7910 and API 579 have been developed to evaluate the structural integrity of pipelines. Based on them, various software, such as PRO-LOCA, PROST, xLPR, etc, have been established to evaluate the safety and reliability of pipelines. However, which of these codes fit best the user’s requirements is a difficult problem because it depends on scientific as well as on personal criteria. Therefore, in this paper, we propose several multiple evaluation criteria to discuss the integrity assessment codes. Furthermore, we apply mathematical methods to evaluate the prediction performance (PP) of the codes PRO-LOCA and PROST.
The PP covers seven criteria: correlation, multimodality, dispersion, risk, conservativeness, robustness and accuracy. The correlation, multimodality and dispersion reflect the stability of the predicted results, while risk, conservativeness, robustness and accuracy illustrate distributional location characteristics (DLC) of the prediction accuracy (PA).
Clearing Effect of Blast Loads from PVBs
Authors: Geng Jihui , Thomas J. Kelly 
Published: November 2022

Abstract
Blast waves from explosion sources such as a pressure vessel burst (PVB) exhibit both positive and negative phases, and the relative magnitude of the positive and negative phases is a function of standoff distance from the explosion source to the target of interest. When an incident blast wave reaches a target building, the blast wave will be reflected off the front wall (i.e., that facing the blast source). Both the blast wave positive and negative phases are affected by this reflection process. A fully reflected blast wave would be produced if the incident blast wave reflected off an infinitely tall and wide wall in a normal orientation. However, when an incident blast wave reflects from a facing wall of finite size, rarefaction waves are created at the edges of the wall and roof, which then sweep inward across the wall. The rarefaction waves result in a clearing effect for both the positive and negative phases. Clearing relieves some of the applied positive phase blast load on the reflected wall. However, clearing may either relieve or enhance the applied negative phase blast load, depending on the blast wave profile and the wall dimensions.
This paper focuses on the determination of negative phase clearing as a function of blast wave and structure parameters. Blast load adjustment factors (i.e., ratio of cleared to fully reflected blast loads) are introduced to characterize blast clearing as a function of these parameters. The purpose of the evaluation described in this paper was to generate a database of the blast clearing for engineering modeling of blast-structure interaction.
Assessment of Gaseous Detonations in Piping Systems and Pipelines
Authors: Clutter Keith , Pease Derrick , Antaki George 
Published: November 2022

Abstract
This paper covers several practical engineering aspects of gaseous detonations in piping systems:
(1) Description of the phenomena and physics of deflagration, detonation, deflagration-to-detonation transition and reflected deflagration-to-detonation transition in piping systems;
(2) Development of transient pressures and loads caused by the detonation process in piping systems and in-line components;
(3) Analytical evaluation techniques and assessment criteria in the context of the ASME B31 Codes. There are several factors that govern the type and severity of gaseous detonations in piping systems including gas composition, initial pressure and ignition location within the piping system. This paper addresses many of these factors and how they affect the characteristics of gaseous detonations in piping systems. The critical characteristic used to determine the structural integrity of piping systems to withstand a detonation is the transient pressure history inside the piping. This paper addresses how to develop such transient pressure histories that can then be readily applied to analytical structural models. There are several methods that can be used to apply a transient pressure history to a structural model of a piping system. This paper addresses some methods that have been used to apply this type of loading to finite element models in Abaqus. These methods could be easily adapted to other FEA software packages. There are also several evaluation methods that can be used to determine the structural integrity of the piping system. This paper addresses some of the more advance methods involving plastic deformation with strain limit damage and explicit time-history solvers. Finally, this paper is specifically focused on piping systems and pipelines where gaseous detonations have unique characteristics compared to more open volumes such as tanks and vessels. A separate paper (PVP2022-84269) addresses the unique characteristics of gaseous detonations in pressure vessels.
Research on Flexural Performance of Curved Carbon Fiber Laminate Composites
Authors: Li Hongfei , Chen Zhiping , Ge Peng , Miao Hao 
Published: November 2022

Abstract
As a clean and efficient secondary energy, hydrogen energy is of great significance for building a clean, low-carbon, safe and efficient energy system. At present, high-pressure gaseous hydrogen storage systems for vehicles mostly use carbon fiber reinforced composite materials as the pressure-bearing materials of hydrogen storage vessel to obtain a lighter mass, so as to ensure the hydrogen storage system has a higher hydrogen storage density. However, unlike traditional steel hydrogen storage vessel, carbon fiber composite hydrogen storage vessel has low rigidity and is prone to bending and deformation during manufacture and use, which can cause safety accidents. Most of the previous studies on mechanical properties have focused on flat laminates, which are of limited help to the study of hydrogen storage vessel. In view of this situation, this work fabricated the curved carbon fiber laminates with the same manufacturing process as the hydrogen storage vessel and investigated their flexural performance using a combination of experimental and finite element methods. The bending experiments of curved carbon fiber laminates at different angles were carried out. And the finite element model for flexural performance prediction of curved carbon fiber laminates was established through validation against the experimental results. A parametric study was further performed to analyzed the influence of carbon fiber winding angle on the flexural performance. This work will provide reference and basis for the subsequent research on the flexural performance of carbon fiber composite hydrogen storage vessel.