bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hot Cell Pulsed Laser Welding of Neutron Irradiated Type 304 Stainless Steel With a Maximum Damage Dose of 28 DPA
Authors: Freyer Paula D. , Tatman Jonathan K. , Garner Frank A. , Frederick Greg J. , Sutton Benjamin J. 
Published: November 2019

Abstract
Radiation-induced degradation of reactor pressure vessels and internals is a concern to the aging nuclear fleet and welding solutions will be required if repair of these irradiated components is deemed necessary. However, the weldability of highly irradiated austenitic materials is significantly diminished due to the presence of irradiation induced helium in the material matrix. Helium-induced weld cracking is a complex phenomenon that is related to the concentration of helium, the heat input from the welding process, and stresses generated during cooling of the weld. During conventional high heat input welding methods such as gas tungsten arc welding, helium bubbles can coalesce and grow on base metal grain boundaries within the heat-affected zone which subsequently causes intergranular cracking.
The objective of this work was to obtain weldability data by characterizing welds made on highly activated, neutron irradiated Type 304 stainless steel containing both radiation-induced helium and microstructural damage such as void swelling. All irradiated materials welding was performed inside a Westinghouse hot cell utilizing a pulsed Nd:YAG laser with welds made on three rectangular samples of highly activated Type 304 stainless steel. The rectangular samples were cut and milled in-cell from sections previously obtained from two neutron reflector hex blocks.
The hex blocks are U.S. Department of Energy owned material and were irradiated for approximately 13 years in the EBR-II sodium cooled fast reactor from 1982 until 1995. The three samples selected for welding have nominal damage doses of approximately 0.4, 11, and 28 dpa with corresponding estimated helium contents of 0.2, 3 and 8 appm helium, respectively.
A number of different weld parameter sets were utilized and included variations of travel speed, wire feed speed and lens-to-work distances. The parameter sets allowed for a range of effective weld heat input levels to be compared. Single pass and multiple pass as well as wire fed and autogenous welds were made. This paper presents the results from post-weld evaluations performed on the three welded irradiated samples, focusing on the reduced tendency for cracks to form adjacent to the weld as a function of weld parameters, lens-to-work distance and helium content.
Quantitative Analysis of the Cause-Effect Relationship of Incidents Occurred in Tank Farm Based on the Method of Logistic Regression
Authors: Wu Xingguang , Hou Lei , Wu Zhuang 
Published: November 2019

Abstract
A large number of incidents occurred in the petrochemical industry due to the continuous accumulation and frequent transfer of dangerous substances. For these historical incident data, a lot of efforts have been made to analyze how and why incidents occurred by use of descriptive statistics, while scarce work was done to in-depth explore the performance characteristics of the causal factors related to different types of incidents. This paper focuses on the relative importance of different causal factors for different types of incidents. A total of 1144 incidents related to tank farms of China during the period 1960–2018 were collected and classified with regard to the intuitive consequences of incidents (fire & explosion, material loss, quality variations, equipment damage and personnel harm) and whether the domino effect was involved (domino incidents and non-domino incidents). The causal factors were classified into five major categories and subdivided into fifteen subcategories. The interaction analysis of each factor with the specific consequence type was performed. The method of logistic regression was used to quantify the relative probability of different causal factors for different types of incidents and to determine which factors have a significant effect on triggering the domino incidents. It is found that human factors and organization/management factors were more common causal factors to lead to different consequences, and the same causal factor has distinct effects on the probability of occurrence for different types of incidents. The results highlight the more critical risk factors for each type of incident and the method can be applied to provide guidance on incident prevention and safety protection.
Modification and Extension of Screening Criteria for Fatigue Analysis
Authors: Shen Jun , Lu Mingwan , Wang Zhenyu , Peng Heng , Liu Yinghua 
Published: November 2019

Abstract
ASME Code VIII-2-2017 and previous versions provided three screening criteria for fatigue analysis. From Edition 2004 to 2017, the design factor for material allowable stress decreased and the considered range of permissible cyclic number for design fatigue curve extended. However, screening criterion are almost unchanged except one restriction: If the specified number of cycles is greater than 106, then the screening criteria are not applicable and a fatigue analysis is required. In this paper, percentage limit of the design pressure in Method A is modified and the specified number of cycles is extended. Some revision suggestions are also proposed to broaden the applicable range of the screening criterion.
A Novel Heat Input Equation for Analysis Welding Thermal Distribution and Welding Residual Stress
Authors: Ma Linwei , Zheng Xiaotao , Wang Wei , Lin Wei , Xu Jianmin , Yu Jiuyang 
Published: November 2019

Abstract
In the numerical simulation of welding residual stress (WRS), the thermal fields distribution of the weld beads during welding process is the basic data to calculate the residual stress due to thermal expansion and extraction. Different welding heat input control method had been proposed and used in the WRS finite element method (FEM) analysis, such as input based on theory, input controlled by temperature monitoring point and so on. Some disadvantages like less calculating efficiency, unexpected temperature variation have been found in these methods. Based on the study of the FEM result of temperature distribution through the weld butter field by using constant unit heat input, the heat transfer activities of each weld bead were researched. And a novel heat input fitted equation was proposed to describe the suitable heat input data for each weld bead of the welding process. More reliable and uniform melting temperature of weld beads with different location could be achieved. And the welding residual stresses from different welding thermal field of theory method, temperature monitoring point method, and novel heat input equation method are compared with the measured WRS results. The results show that the WRS achieved from the novel heat input equations is close to the measured result and has more computational efficiency. The uncertain WRS data used for probability safety assessment were also proposed based on the FEM results with the novel heat input equation method.
Effect of Flow Approach Angle on Acoustic Resonance Excitation of In-Line Tube Bundles in Cross-Flow
Authors: Alziadeh Mohammed , Mohany Atef , Hassan Marwan 
Published: November 2019

Abstract
This paper presents preliminary experimental results on the influence of the flow approach angle on the acoustic resonance excitation of in-line tube bundles in cross-flow. The pitch-to-diameter ratio (P/D) of the in-line tube bundles investigated is P/D = 1.733. The flow approach angle was investigated by physically rotating the tube bundle clockwise relative to the flow direction. The tube bundles are capable of rotating with increments of 5° up to an angle of 45°. For brevity, only the results for the 0° and 30° orientation will be presented herein. For the 0° orientation, two Strouhal frequencies (St1 = 0.437 and St2 = 0.252) were observed. However, only one of these frequencies (St1 = 0.437) was capable of exciting resonance. During resonance, a peak sound pressure level (SPL) of 170 dB was achieved. The Strouhal frequencies and peak SPL agrees well with what has been presented in the literature. For the 30° orientation, only one Strouhal frequency (St1 = 0.98) was measured. At this orientation, the lock-in phenomenon occurred at a much lower flow velocity compared to the 0° orientation with a peak SPL reaching 153 dB. Jumps in the lock-in frequency were observed at the 30° orientation. This phenomenon is associated with two reasons. The first reason is a partial lock-in with an acoustic resonant mode, due to the acoustic energy not being fully trapped within the tube bundle. The second reason is related to the changes in the apparent speed of sound resulting in variations in the acoustic cross-mode frequency depending on where the excitation source is emanating from within the tube bundle. A brief summary of the results is presented in this paper.
Influence of Roughness of Inner Surface of Simple Mechanical Testing Method to Evaluate Influence of High Pressure Hydrogen Gas
Authors: Ogata Toshio , Ono Yoshinori 
Published: November 2019

Abstract
In order to standardize the simple testing method to evaluate mechanical properties using hollow-type specimen in the high pressure hydrogen gas, influences of the hole and inner surface roughness on the relative reduction of area (RRA) and other properties in slow strain rate tensile (SSRT) tests were investigated on different surface finished specimens at 105 MPa hydrogen gas for SUS316L and JIS SNCM439 steels.
There is no influence of the hole and the inner pressure for the yield strength and the tensile strength. The RRA slightly increased in less roughness specimens. So, the axially polished finish for the hollow specimen will be proposed to the standard testing procedures of the SSRT test with this method to evaluate mechanical properties in the high pressure hydrogen gas.
Effect of Plastic Deformation on Hydrogen Embrittlement Sensitivity and Strength of 2.25Cr1Mo0.25V Steel by Synchronous Hydrogen Charging
Authors: Li Qing , Hu Yuqi , Cheng Guangxu , Zhang Zaoxiao , Liang Xiaowu 
Published: November 2019

Abstract
The hydrogenation reactor is an important equipment in petrochemical industry, and it has been produced by many processes such as plate rolling and welding. It served in high temperature, high pressure in hydrogen environment, and faced the risk of hydrogen embrittlement in the stages of operation and downtime cooling. Moreover, plastic deformation is inevitable in the manufacturing process of hydrogenation reactor, and influence mechanical properties and hydrogen resistance of materials. 2.25Cr1Mo0.25V is widely used in the hydrogenation reactor, so it is important to discuss how the plastic deformation affect hydrogen embrittlement sensitivity.
In this paper, the effect of plastic deformation on hydrogen embrittlement sensitivity and strength of 2.25Cr1Mo0.25V steel was investigated by slow strain rate tensile test coupled with electrochemical hydrogen pre-charging and synchronous charging experimental method. The experimental method was better than the common method which performs tensile test after hydrogen charging. Results show that hydrogen embrittlement sensitivity increases with the growth of plastic deformation. When the plastic deformation reached the necking area, the hydrogen embrittlement sensitivity decreases with the growth of plastic deformation. In addition, hydrogen significantly reduced the breaking strength of this steel, while the plastic deformation only increased the yield strength of this steel. The fracture morphology of tensile specimens indicated that the hydrogen embrittlement caused by electrochemical charging was very obvious, and the trend of hydrogen embrittlement degree of the fracture was basically consistent with the result of mechanical experiment. The mechanical properties and fracture micro-morphology of specimens without hydrogen and specimens with electrochemically irreversible hydrogen were compared, it can be obtained that the effect of electrochemically irreversible hydrogen on mechanical properties was negligible.
A New Methodology for CTOD Estimation Using Double Clip Gauge in Pipeline Steels
Authors: Silvestre Marcus N. , Sarzosa Diego F. B. 
Published: November 2019

Abstract
The increasing energy demand has spurred the exploration and production of oil and natural gas in dangerous and hostiles areas. Therefore, accurate calculation of fracture toughness is essential for fitness-for-service (FFS) analyses of critical engineering structures, such as the piping system used in the offshore industry. Regarding the oil and gas exploration in Brazil, 68% of the total area has already been explored, with 71% of that explored area having been developed in recent years. Oil and gas companies have preferentially chosen Crack-tip Opening Displacement (CTOD) due to the vast data of fracture toughness obtained in the past. Moreover, the professionals involved in this area are more familiarly with this parameter since it is easy of understanding because it involves physically crack flank deformation. Different methods to measure CTOD are available in the literature, such as the plastic hinge model, J-integral conversion and double clip gage method (DCGM). Experimentally, DCGM has been widely used to calculate in offshore pipelines. Discrepancies between experimental and numerical measures have been reported. Motivated by the explanation above, this work aims to propose new numerical analyses to evaluate the CTOD using the DCGM using non-linear finite element analyses. New and improved equations are developed to take into accounting knifes position.
Effects of In-Plane and Out-of-Plane Constraint on Fracture Toughness in Austenitic Stainless Steel
Authors: Palmer Iain , Mokhtarishirazabad Mehdi , Moffat Andrew , Mostafavi Mahmoud 
Published: November 2019

Abstract
An improved understanding of the failure behaviour of safety critical component could result in substantial benefits for industry; these include a reduction in design constraints resulting in optimised and cheaper designs, reduced risk and therefore cost. Yet surprisingly, there is little information in design and assessment codes on the behaviour of thin sections. The aim of this paper is to investigate the fracture of thin sections, with reduced out-of-plane plastic constraint, by using a unified measure of constraint. A range of single edge notched bend specimen made of stainless steel 316L were tested. The specimens had a combination of in-plane and out-of-plane constraint levels achieved through different crack lengths and thicknesses. FEA simulations of the tested specimens were conducted to estimate the crack tip stress and strain fields for each, in order to determine Rice and Tracey contour values. Using critical values of Rice and Tracey parameter and a critical area (normalised by thickness) enclosed by this parameter, toughness scaling values for low constraint specimens are calculated.
Measuring the Effectiveness of Metal Weld Overlay Repairs Through Bulge Depth and Bulge Sharpness Analysis
Authors: Araque Egler , Love Darren , Park Stephen , Rutt Daryl , Clark Rick 
Published: November 2019

Abstract
Weld overlay is a repair method that has been used over the last 10 years to limit the growth of bulges and to extend the remaining life of delayed coking drums. Different refinery operators have used varied approaches, ranging from localized patches on specific regions of concern, to bands along circumferential welds, to large sections of structural repair that completely cover a bulged area. The authors have observed the evolution of regions repaired with internal weld overlay on 18 drums over periods of 5 and 8 years. A comparison of bulge sharpness and bulge depth on a year-over-year basis is presented to measure the effectiveness of metal weld overlay and how the overlay impacts continued distortion of the vessel. Furthermore, factors such as the taper ratio in the transition zones, and the distance between the peak of a bulged area and the edges of the weld overlay, are presented as key parameters that affect the likelihood of cracks developing along the transition zones at the upper and lower edges of the repair.
Suppression of Low Energy Natural Modes of Pipe for Mitigation of Turbulence Induced Vibration
Authors: Seena Abu , Lee Donghyung , Kim Juyoul 
Published: November 2019

Abstract
Turbulence induced vibrations are most commonly encountered in industrial piping’s. Several guidelines are available for knowhow and its mitigation in piping designs and acceptable limits of vibration beyond which fatigue failure may occur in pipes. In present paper, it has been emphasized to predict potential turbulence induced vibrations at Design Stage rather than to have the expensive trouble-shooting solutions after the fabrication of system. The detailed review of currently available methods for assessing flow-induced vibrations in piping systems, including current limitations in existing codes and guidelines are discussed. These limitations are centered on the empirical approach currently taken in codes and guidelines. In present paper, a rational approach has been proposed in which the turbulent kinetic energy of the fluid flow is compared against the kinetic energy required to vibrate the pipe beyond its allowable level of vibration. The proposed method has been accessed using a documented case study. The parameters needed to evaluate the relative energies of vibration to turbulent kinetic energy of the fluid flow can be determined from FEA software, which make the present approach practically feasible for the mitigation at design stage.
Spiral Winding Technology for PTFE Gaskets
Authors: Girão Carlos D. , Veiga Jose C. , Valle André C. , Garcia André F. 
Published: November 2019

Abstract
PTFE is used in a variety of applications that goes from wiring in aerospace to non-stick coating in cookware. Some of the PTFE properties, such as high chemical stability and good conformability, makes it excellent for use as a gasket material, especially with aggressive media, pharma and food applications.
The scope of this paper is to present an innovative PTFE gasket manufacturing method for sealing aggressive media. The patented technology represents a unique production process that improves reliability, reduces cost and material waste when compared to traditional production methods. The gasket can be tailored to meet specific needs making it possible for customizations such as radial density variations, assorted colors compositions according to the gasket region and properties, or even use of distinctive fillers along its radius. Comparative data are reported among the developed technology and traditional processes.
Phase-Locked PIV Measurements of Vortex Shedding Characteristics Downstream of Straight Circular Finned Cylinders During Acoustic Resonance
Authors: Islam Rashid , Shaaban Mahmoud , Mohany Atef 
Published: November 2019

Abstract
Excitation of acoustic resonance by flow perturbation downstream of cylinders can result in hazardous levels of acoustic pressure. Previous studies have shown that straight finned cylinders are susceptible to flow-excited acoustic resonance. In this work, the excitation of acoustic resonance by flow around finned cylinders of different fin parameters including the spacing between the fins, the thickness of the fin, and the height of the fin is investigated. All the investigated finned cylinders have the same equivalent diameter. Phase-locked particle image velocimetry (PIV) measurements are carried out during acoustic resonance to characterize the flow field downstream of the cylinders and identify the influence of the fins on the flow structures at the peak of resonance excitation. Results show that straight circular fins excite acoustic resonance at lower velocities and result in higher sound pressure level compared with a single bare cylinder of the same effective diameter. This behaviour is due to the effect of fin parameters on the strength and the formation length of vortices shed during the acoustic cycle. A brief summary of the results is presented in this paper.
Effects of Local Wall Thinning With Crack on Stress Intensity Factor for Pipes Subject to Combined Pressure and Bending
Authors: Tao Joy (Xiaoya) , Zhu Lei 
Published: November 2019

Abstract
At ageing power plants, local thinning of pipework or vessel is unavoidable due to erosion/corrosion or other reasons such as flow accelerated corrosion (FAC) — one of the common degradation mechanisms in pipework of nuclear power plant. Local thinning reduces the structure strength, resulting in crack initiation from the corrosion pit or welding defect when subject to cyclic loading. General practice is to use the minimum thickness of the thinned area to calculate both limit load and stress intensity factor (SIF) in performing Engineering Critical Assessment (ECA) using Failure Assessment Diagram (FAD). Using the minimum thickness is normally overly conservative as it assumes that thinning occurs grossly instead of locally, leading to unnecessary early repair/replacement and cost. Performing cracked body finite element analysis (FEA) can provide accurate values of limit load and SIF, but it is time consuming and impractical for daily maintenance and emergent support. To minimise the conservatisms and provide a guidance for the assessment of locally thinned pipework or vessel using existing handbook solutions, a study was carried out by the authors on the effect of local thinning on limit loads. The study demonstrates that local thinning has significant effect on limit load if the thinning ratio of thinning depth to original thickness is larger than 25%. It concluded that the limit load solutions given in handbooks (such as R6 or the net section method) are overly conservative if using the minimum local thickness and non-conservative if using the nominal thickness.
This paper discusses the effect of local thinning on SIFs of internal/external defects using cracked body finite element method (FEM). The results are compared with R6 weight function SIF solutions for a cylinder. A modified R6 SIF solution is proposed to count for the effect of local thinning profile. Along with the previous published paper on limit load it provides comprehensive understanding and guidance for fracture assessment of the local thinned pipework and vessel.