bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fatigue Assessment and Monitoring of a Dented Pipeline Specimen
Authors: Freire J. L. F. , Paiva V. E. L. , Gonzáles G. L. G. , Vieira R. D. , Maneschy J. E. , D’Almeida A. L. F. S. , Ribeiro A. S. 
Published: November 2019

Abstract
The present paper reports initial results from an investigation program launched with the objective of presenting combinations of analytical, experimental and numerical methods to predict and monitor fatigue initiation and fatigue damage progression in equipment such as pressure vessels, tanks, piping and pipelines with dents or complex shaped anomalies. The monitoring of fatigue initiation and propagation in the actual specimens used nondestructive infrared inspection techniques. Thermoelasticity stress analysis (TSA), three-dimensional digital image correlation (3D-DIC) and fiber optic Bragg strain gages (FBSG) were used to determine strains at fatigue hot spots locations. Strain fields determined from the experimental measurements and from finite element analysis (FEA) were combined with the fatigue Coffin-Manson strain-life equation and the Miner’s fatigue damage rule to predict fatigue life (Nc). Results from one tested 3 m long tubular specimen containing a complex shaped dent are reported and fully analyzed.
Development of Optimized Welding Consumable for Joining Type 410 Martensitic Stainless Steel
Authors: Lawson Benjamin J. , Alexandrov Boian T. , Bundy Joseph C. , Benson David , Penso Jorge A. 
Published: November 2019

Abstract
Type 410 martensitic stainless steel is used in some downstream hydro-processing installations, due to its good resistance to sulfide corrosion and chloride stress corrosion cracking. Industry experience with Type 410 steel welds, using generic welding consumables, has shown difficulties in meeting the weld metal and HAZ hardness and toughness requirements. Recent research has pointed out the wide composition specifications of Type 410 base metal and welding consumables as the leading cause for significant hardness and toughness variations, related to exceeding the A1 temperature during PWHT and formation of fresh martensite, and to retention of significant amounts of delta ferrite. Predictive equations for the A1 temperature and the content of retained delta ferrite were used to identify optimal composition for Type 410 welding consumables with delta ferrite content below 20% and A1 temperature close to the upper end of the ASME specified PWHT range. Experimental metal core filler wire was manufactured and tested to validate the A1 temperature and delta ferrite content. A test weld in Type 410 steel was produced with the new filler wire and subjected to PWHT, metallurgical characterization, and mechanical testing. The weld metal and HAZ properties met the corresponding NACE and ASME hardness and toughness requirements.
Creep Life Evaluations of ASME B31.1 Allowance for Variation From Normal Operations: 11 Materials
Authors: Cohn Marvin J. , Haupt Ron 
Published: November 2019

Abstract
The ASME B31.1-2018 Power Piping Code (Code) paras. 102.2.4, 102.3.3, and 104.8.2 provide an allowance regarding operating above the design temperature and design pressure for short time periods. The concept of allowing occasional operation for short periods of time at higher than the design pressure or design temperature has been in the Code since 1967. These 1967 Code para. 102.2.4 limitations were based on engineering judgment that can now be quantitatively evaluated for the additional creep life consumption (creep rupture damage accumulation).
This study primarily is a quantitative estimate of the permitted increased life consumption, considering minimum creep rupture properties, associated with the 2018 Code operating allowances for piping materials operating in the creep range. Eleven base metal materials are considered in this paper — low carbon steel, 1.25Cr 0.5Mo, 2.25Cr 1Mo, 9Cr 1 Mo V, Type 304 SS, Type 316 SS, Type 316L SS, Type 321 SS, Type 321H SS, Type 347 SS, and Type 347H SS. Results of this evaluation may be used to improve the ASME B31.1 Code, including a technical basis for a possible revision to para. 102.2.4.
Previous studies have revealed that Grade P22 base metal creep damage is slightly more sensitive to stress than Grade P11 material creep rupture damage, and Grade P91 base metal creep damage is substantially more sensitive to stress than Grade P22 material creep rupture damage. Therefore, the allowable pressure and temperature variations result in a range of increased creep life consumption for different materials. The intent of this study was to modify the two Code allowance criteria so that the permitted increased creep life consumption (considering the minimum creep rupture properties of the material) of Allowance B is about the same amount as the increased creep life consumption result of Allowance A for the same material.
Consequently, this study was performed to realign the allowable increased creep rupture life consumption of Allowance B to be approximately equivalent to the allowable increased creep life consumption of Allowance A. If the Allowance B event duration is increased from 80 hours per year to 400 hours per year, the Allowance B increased creep life consumption is slightly less than the Allowance A life consumption for each of these materials.
A Methodology to Assess Elbow Fittings With Localized Material Variations
Authors: Ghosh Pritha , Kulkarni Mandar , Vyvial Brent , Ferguson James 
Published: November 2019

Abstract
Elbow fittings are manufactured using quenching and tempering heat treatment processes. Such fittings can occasionally exhibit localized regions with lower yield strength than the design target, potentially due to non-uniform heat treatment. This paper presents an analytical methodology to examine the influence of these localized lower yield zones on the load capacity of the affected pipe fitting. In parallel, full-scale testing has been performed to quantify the actual response of the elbows under a combination of different loading conditions. The experimental data is used to validate the analytical approach. Details of the analytical method include a two-fold criterion: a global failure based on elastic–plastic stress analysis and a local failure based on the tri-axial strain limit per ASME Boiler and Pressure Vessel Code Section VIII, Division 2. This paper presents the details of the finite element model development, assessment procedure, validation and parametric analysis of the size and location of the low yield zones in the elbow fittings. The fittings are analyzed for three possible operating scenarios: internal pressure, internal pressure with opening moment and internal pressure with closing moment. To characterize the influence of the low yield zone on the strength of the pipe, a parameter termed as “effective yield strength” is introduced. This approach is further demonstrated and found suitable for predicting burst pressures of components with lower yield zones of various diameters and thicknesses. This assessment method can be further extended to assess other pipeline components that exhibit similar behavior.
A Study on Degree of Conservatism of Two Safety Assessment Methods for Piping and Vessels With Defects
Authors: He Meng , Li Haitao , Han Zhiyuan , Xie Guoshan , Sun Liang , Wang Weihua 
Published: November 2019

Abstract
Flaws (defects), such as local thinning due to corrosion, inevitably exist in piping and pressure vessels. These defects can be evaluated using the fitness for service (FFS) method provided in the GB/T 19624 standard. Recently, the GB/T 35013 standard (Fitness-for-service assessment of pressure equipments), which provides another FFS assessment method for local thinning on piping and vessels, has been published. The evaluation method for local thinning in the GB/T 35013 standard is generally similar to that in the API 579-1/ASME FFS-1 (2016), but is totally different from that in the GB/T 19624. In this paper, the differences of the local thinning assessment methods in the GB/T 35013 (or API 579-1/ASME FFS-1 (2016)) and the GB/T 19624 are summarized, and the degree of conservatism comparisons between these standards are presented. The maximum allowable operating pressure (Prmax) that takes into account the effect of defects for straight pipe sections and vessels under different defect sizes and safety factors in these two standards have been calculated and compared. Monte Carlo simulations have been carried out to estimate the failure probability (Pf) and reliability of the straight pipe sections and vessels with different safety factors using the GB/T 19624.
Valve Modeling Methods for Modal Analysis
Authors: Farrell Ronald , Ezekoye L. Ike 
Published: November 2019

Abstract
This paper presents several modeling methods for performing a valve assembly modal analysis. It discusses the background of the methods, their strengths and limitations, and then introduces a new approach that can be used in performing valve modal analysis. An early paper presents a classical approach based on a lumped mass model and the Rayleigh energy principal to determine primary mode natural frequencies. A follow up paper reaffirms the classical method and introduces enhancements. A recent paper provides a comparative study of the classical approach, laboratory testing, and solid modeling results using the finite element analysis program ANSYS Mechanical. In this paper, a third approach is presented, which is an extension of the classical method, where 3-D beam-based geometry is defined using the ANSYS SpaceClaim program that is then ported to ANSYS Mechanical. The classical and solid modeling approaches from the previously cited papers are reviewed to highlight the modeling evolution and then the newly developed approach is presented. An example is presented that compares natural frequency results of the new method and the previous methods.
The motivation for the new method is to provide better compatibility with 3-D piping system models, which are typically used to study the effect of valve mass and stiffness on system response without the complexity of a solid model or the difficulty of communicating the details of a classical model to the system modeler.
Much of the process of creating a 3-D beam model is automated. It uses input from an existing classical model and employs the following ANSYS software packages: SpaceClaim, Workbench, Mechanical, and ACT. A great feature of the resulting 3-D model is that beam geometry is more realistic to scale, and therefore provides valuable user feedback for checking model validity. This approach is an improvement over the classical model where only manual data input validation is possible. Other benefits of the new method are covered in greater detail in the paper.
Large Ranges in Power Piping Girth Weld Creep Rupture Lives
Authors: Cohn Marvin J. , Faham Fatma G. 
Published: November 2019

Abstract
Stress analysis evaluations of high energy piping systems operating in the creep range have revealed that each piping system has a large range of ASME B31.1 Code stresses. It is typical that there are only a few locations of high stresses and many more locations of much lower Code stresses. Over the past 20 years, the authors have evaluated several hundred piping systems operating in the creep range, including main steam, hot reheat, high pressure, and intermediate pressure systems constructed of Grade 11 (1¼-Cr-½Mo-Si), Grade 22 (2¼Cr-1Mo), and Grade 91 (9Cr-1Mo-V) materials. Stress contour plots illustrate the significant range of Code stresses (sometimes factors greater than 2) at various piping system locations. This study also considered the variation of high stress locations for the initial as-designed piping stress analysis versus the as-found stresses associated with field anomalies. The stress contour plots also illustrate that field anomalies in sister units can result in different high stress locations from one unit to another. In addition, significant unintended field anomalies may result in as-found analysis high stress locations at low stress as-designed (expected) analysis locations.
Since there is a large range of stresses in these power piping systems, the girth welds have a significant range of creep rupture lives. In Grade 11 material operating at 1000°F (538°C), an 18% stress increase results in 50% decrease in creep rupture life. In Grade 22 material operating at 1000°F, a 12% stress increase results in 50% decrease in creep rupture life. In Grade 91 material operating at 1060°F (571°C), an 8% stress increase results in 50% decrease in creep rupture life. For Grades 11, 22, and 91, the creep rupture times are a function of stress to the powers of 4, 6, and 9, respectively. Consequently, the evaluation of the large range of stresses in these piping systems revealed that the piping system girth welds can have creep rupture lives varying by more than a factor of 10. The large range of piping stresses and associated large range in creep rupture lives within a piping system are illustrated as stress histograms for several example piping systems. Four case studies illustrate successful selection of girth weldments with the most in-service related creep damage.
Magnetic Barkhausen Noise Method for Characterisation of Low Alloy Steel
Authors: Kadavath Gokulnath , Mathew Jino , Griffin James , Parfitt David , Fitzpatrick Michael E. 
Published: November 2019

Abstract
Application of NDE techniques to operating reactor materials is useful for the determination of deviations resulting from material inhomogeneity and long-term degradation of properties from irradiation damage. A new programme, Nondestructive Evaluation System for the Inspection of Operation-Induced Material Degradation in Nuclear Power Plants (NOMAD), focuses on the non-destructive investigations of Reactor Pressure Vessel (RPV) steels in ageing reactors to better assess the integrity for lifetime management. In this study, Magnetic Barkhausen Noise (MBN) is used to characterise the effect of inhomogeneties in a Jominy end-quench test specimen subjected to differential cooling rates. The effect of material state encompassing different variables such as surface roughness, microstructure, hardness and residual stress is correlated with the MBN Root Mean Square (RMS) parameter in order to enhance the understanding of the embrittlement phenomena. These studies will contribute to the development of a tool that can monitor and quantify the extent of material degradation in operating nuclear power plants.
Computational Evaluation of Thermal Barrier Coatings: Two-Phase Thermal Transport Analysis
Authors: Irick Kevin , Fathi Nima 
Published: November 2019

Abstract
In the power plant industry, the turbine inlet temperature (TIT) plays a key role in the efficiency of the gas turbine and, therefore, the overall — in most cases combined — thermal power cycle efficiency. Gas turbine efficiency increases by increasing TIT. However, an increase of TIT would increase the turbine component temperature which can be critical (e.g., hot gas attack). Thermal barrier coatings (TBCs) — porous media coatings — can avoid this case and protect the surface of the turbine blade. This combination of TBC and film cooling produces a better cooling performance than conventional cooling processes. The effective thermal conductivity of this composite is highly important in design and other thermal/structural assessments. In this article, the effective thermal conductivity of a simplified model of TBC is evaluated. This work details a numerical study on the steady-state thermal response of two-phase porous media in two dimensions using personal finite element analysis (FEA) code. Specifically, the system response quantity (SRQ) under investigation is the dimensionless effective thermal conductivity of the domain. A thermally conductive matrix domain is modeled with a thermally conductive circular pore arranged in a uniform packing configuration. Both the pore size and the pore thermal conductivity are varied over a range of values to investigate the relative effects on the SRQ. In this investigation, an emphasis is placed on using code and solution verification techniques to evaluate the obtained results. The method of manufactured solutions (MMS) was used to perform code verification for the study, showing the FEA code to be second-order accurate. Solution verification was performed using the grid convergence index (GCI) approach with the global deviation uncertainty estimator on a series of five systematically refined meshes for each porosity and thermal conductivity model configuration. A comparison of the SRQs across all domain configurations is made, including uncertainty derived through the GCI analysis.
Determinants of longitudinal change in insulin clearance: the Prospective Metabolism and Islet Cell Evaluation cohort
Authors: Semnani-Azad Zhila , Johnston Luke W , Lee Christine , Retnakaran Ravi , Connelly Philip W , Harris Stewart B , Zinman Bernard , Hanley Anthony J 
Published: November 2019

ObjectiveTo evaluate multiple determinants of the longitudinal change in insulin clearance (IC) in subjects at high risk for type 2 diabetes (T2D).Research design and methodsAdults (n=492) at risk for T2D in the Prospective Metabolism and Islet Cell Evaluation cohort, a longitudinal observational cohort, had four visits over 9 years. Values from oral glucose tolerance tests collected at each assessment were used to calculate the ratios of both fasting C peptide-to-insulin (ICFASTING) and areas under the curve of C peptide-to-insulin (ICAUC). Generalized estimating equations (GEE) evaluated multiple determinants of longitudinal changes in IC.ResultsIC declined by 20% over the 9-year follow-up period (p<0.05). Primary GEE results indicated that non-European ethnicity, as well as increases in baseline measures of waist circumference, white cell count, and alanine aminotransferase, was associated with declines in ICFASTINGand ICAUCover time (all p<0.05). There were no significant associations of IC with sex, age, physical activity, smoking, or family history of T2D. Both baseline and longitudinal IC were associated with incident dysglycemia.ConclusionsOur findings suggest that non-European ethnicity and components of the metabolic syndrome, including central obesity, non-alcoholic fatty liver disease, and subclinical inflammation, may be related to longitudinal declines in IC.
Gallstone ileus: a review
Authors: Inukai Koichi 
Published: November 2019

BackgroundGallstone ileus is an important complication of cholecystolithiasis. In general, surgery is the treatment of choice for such cases, but clinicians face difficulty in the selection of an appropriate approach. Closure of a cholecystoenteric fistula can be achieved through one-stage or two-stage operation. Two-stage operation has a lower mortality rate than a one-stage procedure, but persistence of the cholecystoenteric fistula is associated with the risk of carcinogenesis and recurrence of gallstone ileus.ObjectiveThis study reviews the different surgical approaches according to the impaction site of the gallstone, using data of previous studies by our group and clinical reports in the literature.ConclusionsFirst, for cases involving impaction at the duodenum, the cholecystoenteric fistula can be repaired in the same surgical field, and one-stage operation obtains favourable outcome; hence, one-stage operation is considered as treatment of choice. Second, for cases involving impaction at the small intestine, natural closure of the cholecystoenteric fistula or low mortality is expected; hence, two-stage operation may be performed, possibly using minimally invasive laparoscopy. Third, for cases involving impaction at the colon, natural closure of the cholecystocolonic fistula is unlikely, and patients have a high risk of reflux cholangitis due to faecal fluid; hence, one-stage operation is considered as treatment of choice.
The catastrophic and impoverishing effects of out-of-pocket healthcare payments in Kenya, 2018
Authors: Salari Paola , Di Giorgio Laura , Ilinca Stefania , Chuma Jane 
Published: November 2019

IntroductionProgress towards effective service coverage and financial protection—the two dimensions of Universal Health Coverage (UHC)—has been limited in Kenya in the last decade. The government of Kenya has embarked on a highly ambitious reform programme currently being piloted in four Kenyan counties and aiming at national rollout by 2022. This study provides an updated assessment of the performance of the Kenyan health system in terms of financial protection allowing to monitor trends over time. In light of the UHC initiative, the study provides a baseline to assess the impact of the UHC pilot programme and inform scale-up plans. It also investigates household characteristics associated with catastrophic payments.MethodsUsing data from the Kenya Household Health Expenditure and Utilization Survey (KHHEUS) 2018, we investigated the incidence and intensity of catastrophic and impoverishing health expenditure. We used a logistic regression analysis to assess households’ characteristics associated with the probability of incurring catastrophic health expenditures.ResultsThe results show that the incidence of catastrophic payments is more severe for the poorest households and in the rural areas and mainly due to outpatient services. Results for the impoverishing effect suggest that after accounting for out-of-pocket(OOP) payments, the proportion of poor people increases by 2.2 percentage points in both rural and urban areas. Thus, between 1 and 1.1 million individuals are pushed into poverty due to OOP payments. Among the characteristics associated with the probability of incurring OOP expenditures, socioeconomic conditions, the presence of elderly and of people affected by chronic conditions showed significant results.ConclusionKenya is still lagging behind in terms of protecting its citizens against financial risks associated with ill health and healthcare seeking behaviour. More effort is needed to protect the most vulnerable population groups from the high costs of illness.