bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Ageing on Residual Stresses in a Girth Welded Stainless Steel 316 L Pipe
Authors: Coulthard R. J. , Mostafavi M. , Truman C. E. 
Published: November 2019

Abstract
Residual stresses within welded components can redistribute when exposed to high temperatures and large levels of loading. The ageing process for a specimen attempts to replicate the temperature regime experienced during typical service use of the component, redistributing stresses from the as-welded condition to post-ageing. The aim of this investigation was to study the effects of ageing on weld residual stress redistribution and to evaluate the changes in the residual stress profiles before and after the pipe had been aged.
In this investigation the through thickness residual stresses within a narrow gap girth TIG welded stainless steel 316L pipe were measured. The ageing of the pipe specimen involved heating to 400°C for 3000 hours. To measure residual stress the incremental Deep-Hole Drilling (iDHD) method was employed; two measurements were taken, once before and after ageing.
Analysis of the measured pre and post-ageing residual stresses showed a consistent reduction in the magnitude of approximately 50 MPa, corresponding to the change in the yield stress of the material at room and elevated (400°C) temperatures; the maximum residual stress, of 450 MPa, was measured at 4 mm from the external surface of the pipe.
Comparison of Fracture Assessments of Corrosion Pits Using Sharp and Blunt Notched Crack Procedures
Authors: Meek Caroline , Spence Matthew 
Published: November 2019

Abstract
Historically, when determining failure criteria for a cracked structure, the structure has been assessed with the crack tip assumed to be infinitely sharp. For scenarios where it can be shown that the crack tip is blunt, such as for corrosion pits, this may lead to overly pessimistic assessments which can have implications for remnant life assessments of structures.
Recent research has been carried out to evaluate structures with the crack tip as a blunt notch with a radius, and to develop a notch acuity parameter. That research led to formulae for adapting either the failure assessment curve or the failure assessment points utilising the notch acuity parameter for ferritic materials.
This paper analyses various configurations of crack and specimen geometry, crack tip notch acuity parameter and crack spacing. It takes a finite element model of a cracked structure with an infinitely sharp crack and compares the failure parameters to those of equivalent notched cracks. The comparison is completed using the formulae derived in recent literature and those determined using finite element models with the blunt notched radii at the crack tip incorporated into the model.
Investigation of the Stresses and Interaction Effects of Nozzle-Cylinder Intersections When Subject to Multiple External Loads
Authors: Bozkurt Murat , Nash David , Uzzaman Asraf 
Published: November 2019

Abstract
Analyzing and solving the problem of practical cylinder-cylinder pressure vessel intersections is challenging when using a finite element approach. Although numerous theoretical and finite element solutions have been developed for the cylinder-cylinder intersection problem, there remains the requirement for an updated, innovative model which takes account of all practical as-fabricated features including fillets and crotch corner ground radii. This study presents the development of a suitable model, based on the results of a parametric macro study, which is able to compare all of these operations on a single, high fidelity model. This study considers a cylindrical pressure vessel with a single nozzle connection without reinforcement plate and examines the maximum stress values in the nozzle-shell intersection area (crotch corner) under the various loads applied to the nozzle. Additionally, internal pressure and external load actions on the nozzle, including effects of circumferential, torsional, and longitudinal moments are compared using a suitable finite element approach. Furthermore, equations and solutions for external loads in spherical and cylindrical shells are given in WRC Bulletins 107 and 537. Therefore, comparisons with the results obtained from these are made for validation purposes and the overall impact of the new as-built approach is presented.
Integrity Assessment of Cables Under Postulated Electrical Fire Accidents in a Zero-Power Research Reactor
Authors: Jyung Jae-Min , Chang Yoon-Suk 
Published: November 2019

Abstract
Fire protection and appropriate management are important to ensure security of nuclear facilities alike other industries. While relevant hazard analyses have been successfully carried out for commercial reactors, based on recently strengthened IAEA guideline and national standards, examination of research reactors is also required. The objective of this study is to represent integrity assessment of safety related cables connected to operating console in the control room of a zero-power research reactor. Two postulated electrical fire scenarios were identified among diverse accident causes and systematically analyzed by two numerical softwares with different turbulence models. Both polyvinyl chloride and cross-linked polyethylene were selected, respectively, as the representatives of various thermoplastic and thermoset cable materials. As results, temperature and heat flux profiles of the cables were calculated. Their maximum values were compared with the corresponding damage criteria, of which details and key findings will be discussed.
Property Degradation and Residual Life Assessment of Service Exposed Reformer Tubes
Authors: Han Zhiyuan , Xie Guoshan , Cao Luowei , Wang Likun , Sun Guohao 
Published: November 2019

Abstract
Reformer furnaces are widely used in a hydrogen plant to obtain hydrogen from hydrocarbon. The radiantt coils tubes are the most critical components of a reformer furnace, which can be heated up to 850 °C or higher temperature for long time during service. The failure of tubes usually happened before the designed life due to over-heating or unexpected damage, which usually leads to unplanned shutdown of plant and great losses. Thus, it is important to assess the damage conditions and residual life of furnace tubes. This study is an attempt to investigate the property degradation and residual life for service exposed reformer tubes of a hydrogen reformer furnace after 6 years service. Microstructural and mechanical experiments were carried out to reveal the property degradation, included optical observations, scanning electron microscope (SEM) observations, room temperature tensile tests, high temperature tensile tests, and stress rupture tests. Finite element analysis was also used to investigated the influence factors on the stress of tubes. The residual life of furnace tube was estimated based on these experimental and simulation results.
Experimental Studies on Discharge Characteristics of the Typical Thermally-Activated Pressure Relief Device Used for High-Pressure Hydrogen Storage Cylinder in Different Fire Conditions
Authors: Bo Ke , Zheng Jinyang , Gu Chunlin , Zhao Baodi , Huang Qianghua , Liao Binbin 
Published: November 2019

Abstract
Thermally-activated pressure relief devices (TPRD) with glass bulbs or fusible alloy are applied to high-pressure hydrogen storage cylinders (HHSC), in order to release hydrogen gas from the cylinder in fire accidents. In this paper, cylinders with different TPRDs were tested in two groups using different bonfire test methods. In group A, the fire was set exactly under the TPRD. While in group B, the fire was set 80 mm beside the TPRD. The result shows that TPRDs with glass bulb and fusible alloy acted in a similar way when the fire was under the cylinder and the TPRD. However, they acted in a quite different way when the fire was only under the cylinder and beside the TPRD. In group A, hydrogen was released continuously from TPRD both for glass bulb and fusible alloy. In group B, hydrogen was released continuously from the TPRD using glass bulb which was similar to the group A. However, for TPRDs using a fusible alloy, hydrogen was released in several stages taking much more time. The results are instructive for the design and selection of TPRDs on HHSC.
Elastoplastic Solution and Limit Load Analysis of Orthotropic Cylindrical Shell Subjected to Internal Pressure
Authors: Zhao Yujie , Xu Min , Li Chunxiao , Zhou Binbin , He Xiaohua , Zhou Changyu 
Published: November 2019

Abstract
Cylindrical shell structure is widely used in pressure vessels. In this paper, the orthotropic cylindrical shell structure is analyzed based on the theory of elastoplastic mechanics and the Hill48 yield criterion, the elastoplastic limit load expression of the orthotropic cylindrical shell and the corresponding three-dimensional stress formulas at different stages are obtained. The effect of the radius ratio and the yield strength ratio on the elastic limit load and plastic limit load of the cylindrical shell are also discussed. Finally, the orthotropic cylindrical shell structure is simulated by finite element method, the numerical results verify the correctness of the analytical solutions.
Development of New Design Fatigue Curves in Japan: Discussion of Crack Growth Behavior in Large-Scale Fatigue Tests of Carbon and Low-Alloy Steel Plates
Authors: Takanashi Masahiro , Ueda Hiroshi , Saito Toshiyuki , Ogawa Takuya , Hayashi Kentaro 
Published: November 2019

Abstract
In Japan, the Design Fatigue Curve (DFC) Phase 1 and Phase 2 subcommittees, which are a part of the Atomic Energy Research Committee of the Japan Welding Engineering Society, have proposed new design fatigue curves and fatigue analysis methods for carbon, low-alloy, and austenitic stainless steels. To confirm the validity of the proposed design fatigue curves, a Japanese utility collaborative project was launched, and the authors conducted fully reversed four-point bending fatigue tests for large-scale specimens of carbon steel and low-alloy steel plates. Subsequently, in a previous paper (PVP2018-84456), the authors reported that the fatigue lives determined by the best-fit curve proposed by the DFC subcommittee corresponded to those of approximately 1.5–7.0-mm-deep crack initiation in large-scale specimens.
In this study, the fatigue crack initiation and propagation behavior observed in large-scale specimens was investigated by using a plastic replica and beach mark method. Similar to the case of small-sized specimens, in the large-scale specimens, multiple fatigue cracks initiated at an early stage of testing, and propagated with coalescence to penetrate the specimen width. However, no fatigue cracks were detected at the design fatigue life. Approximately 100-μm-long cracks were observed, albeit only after the specimen was subjected to a number of cycles that corresponded to approximately 3.5 times the design fatigue life.
According to NUREG/CR-6909 Rev.1, the crack depths in small-sized round bar specimens at the fatigue lives, which are defined by 25%-stress-drop cycles, are reported to be approximately 3 mm. The results of the large-scale tests indicated that regardless of the specimen size, nearly the same phenomenon occurred on the specimen surface until approximately 3–4-mm-deep crack initiated. The size effect was mainly caused by the stress gradient. The finite element analysis indicated that the stress gradient in the large-scale specimen was gentle owing to the large thickness of the specimen, and the stress in the vicinity of the surface was considered to be uniform. In conclusion, the size effect was not apparent. As the same conclusion can be applied to considerably larger actual components, designers do not need to consider the size effect when designing pressure vessels or piping by using the design fatigue curve determined based on small-sized specimens.
Consideration of Thermal Embrittlement in Alloy 316H for Advanced Non-Light Water Reactor Applications
Authors: Ren Weiju , Lin Lianshan 
Published: November 2019

Abstract
To construct advanced non-light water reactors (ANLWRs) operating in the temperature range above that for the traditional light water reactors (LWRs), Alloy 316H is one of the candidate materials because of its inexpensiveness, significant service experience, and qualification for nuclear applications by the American Society of Mechanical Engineers (ASME). However, during the life span at temperatures expected for the ANLWRs, the alloy is likely to experience thermal embrittlement that has not been a concern for the traditional LWRs. To prepare for the development, the possibility of adverse thermal embrittlement effects on Alloy 316H performance in the ANLWRs must be evaluated and a technical basis regarding thermal embrittlement, if necessary, must be established for structural integrity analysis to provide reasonable assurance of adequate nuclear safety protection.
In this paper, current technical basis for nuclear applications of Alloy 316H deterioration from thermal aging is briefly introduced. The likelihood of adverse thermal embrittlement effects on Alloy 316H performance is evaluated through historical data on microstructural and mechanical property evolution. Characterization of thermal embrittlement is then discussed, followed by a review of predictive models and trend curves for alloy embrittlement. Based on the review and evaluation, technical gaps for addressing thermal embrittlement issues are identified and gap-filling actions are recommended for establishing a technical basis to enable adequate consideration of thermal embrittlement in Alloy 316H applications to the ANLWRs.
Design and Material Selection for Acoustic Isolated Pipe Supports
Authors: Eijgenhuijsen Menno , Masand Girish 
Published: November 2019

Abstract
Health, Safety and Environmental (HSE) Reports prepared for the detailed design phase of facilities in the Oil & Gas or Petrochemical industry often recommend the application of acoustic (noise) insulation at specific pipe sections. Those recommendations include the use of acoustic isolation material at pipe support locations, refer Fig.1. The aim for using acoustic isolation supports is to limit noise being transmitted to the supporting structures and surrounding environment. High noise levels may be flow induced due to the presence of various equipment restrictions and discontinuities in gas and steam piping. Specific material requirements and adequate guidelines for designing effective acoustic isolation supports are generally not provided in abovementioned HSE reports and project specifications. The purpose of this paper is to create an awareness of the importance to carry out design of acoustic isolation supports based on proper engineering and to start this activity at an early stage in a project. This paper describes the basic theory of acoustic isolation and specific considerations in the design of pipe supports to minimize transmission of noise to underlying support structures while being effective to carry the piping loads. The paper also briefly describes a test method to determine the dynamic stiffness for isolation material, an important property to assess whether a material can be used for effective isolation. The paper ends with a comparison of properties for some materials and their effectiveness when used to isolate noise.
Pathway to Evaluate Printed Circuit Heat Exchanger Based on Simplified Elastic-Perfectly Plastic Analysis Methodology for High Temperature Nuclear Service
Authors: Devi Urmi , Morrison Machel , Hassan Tasnim 
Published: November 2019

Abstract
Printed Circuit Heat Exchangers (PCHEs) are well-suited for Very High Temperature Reactors (VHTRs) due to high compactness and efficiency for heat transfer. The design of PCHE must be robust enough to withstand possible failure caused by cyclic loading during high temperature operation. The current rules in ASME Code Section III Division 5 to evaluate strain limits and creep-fatigue damage based on elastic analysis method have been deemed infeasible at temperatures above 650°C. Hence, these rules are inapplicable for temperatures ranging from 760–950°C for VHTRs. A full inelastic analysis method with complex constitutive material description as an alternative, on the other hand, is time consuming; hence impracticable. Therefore, the simplified Elastic-Perfectly Plastic (EPP) analysis methodology is used as a solution in ASME Code Section III Division 5. The current literature, however, lacks any study on the performance evaluation of PCHE through EPP analysis. To address these issues, this study initiates the pathway of EPP evaluation of an actual size PCHE starting with elastic orthotropic analysis in the global scale. Subsequently, preliminary planning for analyzing intermediate and local submodels are provided to determine channel level responses to evaluate PCHE performance against strain limits and creep-fatigue damage using Code Case-N861 and N862 respectively.
Vibration Design of Amine Regenerator Tower and its Piping System
Authors: Park Jae-Yeol , Chae Minsung 
Published: November 2019

Abstract
Fluid induced vibration in high-elevation tower and its piping system is examined with on-site measurement, numerical simulation, and analytical model. In this article, Amine regeneration tower in gas separation plant is subjected to investigation since significant vibration in both tower and its piping system prevents the normal operation especially with increased loading capacity. Measurement in frequency domain for inlet piping system shows single dominant peak as well as small peaks in low frequency range. In search of solution, analytical study with computational fluid dynamics model is conducted to reduce fluid velocity which results in decreased dynamic force in both piping system and regeneration tower and reduces the fluid-induced vibration associated with slug flow. Based on the fluid dynamics study, piping modification is designed and applied to the piping system and tower and vibration improvement is achieved as expected.
Research and Development of Three-Dimensional Isolation System for Sodium-Cooled Fast Reactor: Part 4 — Proposal of Optimal Combination Method for Disc Spring Units and Newly Friction Model for Sliding Elements
Authors: Fukasawa Tsuyoshi , Okamura Shigeki , Somaki Takahiro , Miyagawa Takayuki , Uchita Masato , Yamamoto Tomohiko , Watakabe Tomoyoshi , Fujita Satoshi 
Published: November 2019

Abstract
The authors proposed a newly three-dimensional isolation system, consisting of a rubber bearing, vertical oil dampers and disc spring units, to reduce the seismic response in the vertical direction as well as horizontal direction. This isolation system is employed with a number of disc spring units to provide the vertical restoring force to the superstructure. The disc spring units are combined by three disc springs in parallels and they are are stacked in six serials. The vertical restoring force has susceptible to the variation forces for the individual disc springs because the disc spring units are combined in the six serials. The The purpose of this paper is to present two kinds of proposal to improve the quality control of our isolation system and the prediction accuracy of seismic response. The first is to create the the optimal combination method for the disc spring units using the meta-heuristic algorithm to minimize the variation of vertical vertical restoring force. The proposed optimal method was verified through the result of static loading tests using the 72 disc springs which have the half dimensions to full scale. The second is to create a newly analytical model for the friction force caused by polymeric materials. The proposed analytical model was verified by comparing the loading test results. Moreover, the seismic isolation performances were clarified by the seismic response analysis that consider the vertical restoring force of the disc spring units which were combined using the optimal method and the friction force of sliding elements which were modeled by the proposed friction model. This analytical result revealed that our isolation system can reduce the seismic response not only for the high frequency components but also the low frequency ones.
Proposal for Improving Insulation Installation Practice for Superheated Steam Line
Authors: Kanamaru Shinichiro , Qian Shaoxiang , Yamada Yoshinori 
Published: November 2019

Abstract
Insulation is widely used in process plants to reduce heat loss of process fluids in piping and pressure vessels. However, insulation is often not installed around Normally No Flow (NNF) line pipe. In a refinery plant, a steam leak incident happened due to a through-wall crack, which was found around the connection between an insulated superheated steam line with insulation and an uninsulated safety valve line. The through-wall crack was identified to be a fatigue crack initiated at the inner surface by fractography. An unsteady Computational Fluid Dynamics (CFD) analysis was performed to identify mechanism of the through-wall crack initiation. Based on the observation of fractography and the CFD analysis, it is inferred that the through-wall crack was induced by a high cycle thermal fatigue phenomenon, so-called thermal striping, due to incomplete mixing of hot and cold fluids. Many thermal striping incidents in nuclear plants and process plants have been reported. In view of the above fact, it is suggested that conventional insulation installation practice for NNF line pipe, in particular superheated steam line, may cause cracks due to thermal striping around the connection between main superheated steam pipe and branch dead-end leg. In this paper, a convenient guideline for insulation installation is proposed for a dead-end leg of superheated steam line to prevent cracks caused by thermal striping. The guideline can be used to judge the necessity of insulation installation, based on degree of superheat of steam.
Simplified SCC Simulation Considering Growth Arrest at Fusion Line of Weld
Authors: Okada Hiroshi , Kamaya Masayuki , Yusa Yasunori 
Published: November 2019

Abstract
The authors have carried out a series of developments on methods to perform natural crack propagation analysis in last several years. This paper describes the results of SCC (stress corrosion cracking) growth analyses under some assumptions on the growth behaviors and assumed stress distributions. The SCC growth was assumed to initiate in the weld metal and to be arrested at the fusion line of weld. Although it is possible to model a realistic configuration of weld, it may take a large amount of modeling and computational cost. Thus, an appropriate simplification for the SCC growth prediction is demanded. Hence, two kinds of welds were considered in the present investigation. One had a realistic configuration. The other was a simplified one whose volume of the weld metal had a rectangular shape. Thus, a further simplification was made such that the cracks were assumed to be rectangular in their shapes. SCC growth analyses were performed by finite element based crack propagation simulation software using a remeshing technique that was developed and has been updated by the authors. The paper describes the method of crack propagation analysis briefly and presents the results of the SCC growth analyses. Some discussions on the simplification of the SCC propagation analysis are presented. Then, it is concluded that an appropriate use of rectangular shaped crack may give a conservative prediction on the SCC growth prediction.