bluuebunny/crossref_metadata_2025_split huggingface dataset:
Well Control Simulation With Non-Aqueous Drilling Fluids
Authors: Chagas Felipe , Ribeiro Paulo R. , Santos Otto L. A. 
Published: November 2019

Abstract
The demand for energy has increased recently worldwide, requiring new oilfield discoveries in order to supply this need. Following this demand increase, challenges grow in all areas of the petroleum industry especially those related drilling operations. Due to hard operational conditions found when drilling complex scenarios such as high pressure/high temperature zones, deep and ultradeep waters and other challenging ones, the use non-aqueous drilling fluids became a must. The reason for that is because this kind of drilling fluid is capable to tolerate these extreme drilling conditions found in those scenarios. However, it can experience changes in its properties as results of pressure and temperature variations, requiring special attention during some drilling operations, such as the well control. The well control is a critical issue since it involves safety, social, economic and environmental aspects. To support well control operations and preserve the well integrity, well control simulators are very useful to verify operational parameters and to assist drilling engineers in the decision making process during well control operations and kick situations. Well control simulators are also important computational tools for rig personnel training. This work presents well control research and development contributions, as well as the results of a computational well control simulator that applies the Driller’s Method and allows the understanding the thermodynamic behavior of synthetic drilling fluids, such as n-paraffin and ester base fluids. The simulator employed mathematical correlations for the drilling fluids PVT properties obtained from experimental data.The simulator results were compared to a test well data set, as well to published results from other kick simulators.
Capturing Two Consecutive Green Water Events by Convolution
Authors: Hernández-Fontes Jassiel V. , Silva-Casarín Rodolfo , Mendoza Edgar 
Published: November 2019

Abstract
Capturing the propagation of green water events on in ships and other marine structures is of importance when studying the hydrodynamic effects on their motion and the structure’s behavior. Analytical models used to predict green water elevations, such as dam-break models, have been considered to represent time series of water elevations of single green water events. This paper presents the use of a convolution approach to represent the time series of water elevations of two consecutive green water events on deck of a fixed structure. The procedure is described considering green water events, generated with regular waves, on a barge-type fixed structure. Its application is compared with results available elsewhere in the literature. With the assumptions related with the selection of input parameters of the convolution model, and considering only the first green water event, the results show that this methodology allows two consecutive green water events to be captured acceptably. It is hoped that this methodology will be useful in further time-domain applications which study the dynamic behavior of structures subjected to green water.
Quantitative Wear Estimation for Mooring Chain of Floating Structures and its Validation
Authors: Takeuchi Takaaki , Utsunomiya Tomoaki , Gotoh Koji , Sato Iku 
Published: November 2019

Abstract
For reducing maintenance cost of floating offshore wind turbine structures, it is necessary to establish quantitative wear estimation method for the mooring chains. In this paper, attempts have been made to improve the accuracy and applicability of the estimation method in the following steps.
By using the wear analysis method between the links of mooring chain that Gotoh et al. investigated with the finite element analysis software (MSC. Marc), the expression of the wear amount was obtained, which was a proportional functional form associated with sliding angle and tension.
The relative sliding angle and tension between links were analyzed by using a multibody dynamics software (MSC. Adams). A spar-type floater moored with three catenary mooring lines at Goto, Nagasaki prefecture, Japan was analyzed. Here, the floating body was modelled as a rigid body and mooring chains were modelled by mass-spring (lumped mass) model.
From these results, the wear amounts calculated by using the estimation formula and relative sliding angle and tension between links were compared with the measured wear amounts for mooring chain of the floater which was deployed for about one-year at Goto. The cases with only waves and those with wind and waves were analyzed.
From the comparison between the simulation results and the measured ones, it was found that the proposed method can fairly predict the wear amount of mooring chains. However, it was also found that the proposed method has a tendency to overestimate the measured results. These reasons were discussed in the paper.
Computations of Hydrodynamic Forces on Vessels Advancing in Waves by Four-Node Higher-Order Boundary Element Method
Authors: Yang Yuntao , Zhu Renchuan , Huang Shan 
Published: November 2019

Abstract
A higher-order boundary element method (HOBEM) using three dimensional translating-pulsating (3DTP) Green’s function is developed and applied to calculate the hydrodynamic forces on vessels advancing in waves in the present study. In this HOBEM, geometrical and physical variables are expressed by the shape functions defined by four nodal values; and Green’s function in Havelock form is adopted in the numerical implementation. The Gauss-Legendre quadrature is first adopted for the integral of 3DTP Green’s function over panel. However, due to the highly oscillating characteristic of Green’s function near the free surface, numerical instability is observed in the final results. To avoid this unstable problem, an improved algorithm for the integral of Green’s function is proposed. We discretize the panel into a series of horizontal line segments and derive an integral expression of 3DTP Green’s function distributing on the line segment. By accumulating a series of 3DTP Green’s function distributing on various horizontal line segments, the panel integral of Green’s function is obtained. To validate the performance of the improved algorithm, hydrodynamic forces on a mathematical ship model Wigley III are first calculated. The results are compared with those of the former algorithm and experimental data, which shows that improved algorithm is more stable and accurate. The present HOBEM is then applied to analyse the radiation and diffraction problems for a Series 60 hull and a catamaran hull. The computed hydrodynamic coefficients and wave forces are found to be in good agreement with experimental data.
Flange Neck Creep Damage Below API 579-1/ASME FFS-1 Creep Damage Threshold Triggered by Ring Joint Dissimilar Flanges
Authors: Ishizaki Yoichi , Yonekawa Futoshi , Suzuki Teppei , Hase Akira 
Published: November 2019

Abstract
Reduced flange design is commonly used for fixed bed reactor top nozzles due to the easier provision of manway access for down time maintenance. In this design, a dissimilar flange design is often opted for a material break point of the unit to avoid a dissimilar weld in the piping system.
This design concept is also adopted our fixed bed reactors. The vessel is made of 2.25Cr steel including 40inch top nozzle. On the 2.25Cr top nozzle, 347SS dissimilar reduced flange was provided for manway access purpose in conjunction with top nozzle. It had been operated for 54,000Hrs until the reduced flange neck experienced minor cracks. As the total operating hours reached 140,000Hrs, cracks were propagated and leaked. According to their inspection record of those cracks, a creep damage like pattern was observed while its operating temperature was 520Deg. C, that was below the 550Deg.C of ASME Sec II Part D[1] allowable stress table time dependent allowable stress range, and also below the 537Deg.C of potential creep damage threshold indicated in API 579-1 / ASME FFS-1[2] Table 4.1 which is the same with API 571 Table 4.3[3]. As we conducted FEM analysis using an isochronous curve based on API 579/ASME FFS-1 Omega Method[2], the results well explained the actual damage and life, and confirmed a creep damage could happen below the creep damage threshold of API 579-1 / ASME FFS-1[2] and API 571[3], depending on the multiaxial stress state.
In this paper, the detail of the inspection findings and isochronous model FEM analysis including remaining life assessment as well as comparison between the damage and analysis will be discussed.
Effect of Interference on Stress and Strain Distribution on the Spherical Sealing Cup of a PIG in Dented Pipeline
Authors: Zhang Hang , Dong Jinhui , Cui Can , Liao Ningsheng 
Published: November 2019

Abstract
Regular pigging operation of the pipeline inspection gauges (PIGs) is crucial for pipeline transportation. However, the PIG is often stuck when it runs in the oil and gas pipeline due to the interaction between spherical sealing cup and dent inside the pipe. The stress and strain distribution of the outer edge of the spherical sealing cup can provide a reference to the problem of understanding the blockage. In this study, numerical simulation of a PIG with spherical sealing cups runs through a pipe with dented wall is presented using MSC Marc 2016. Effects of the interference (δ) of the spherical sealing cup on the stress and strain distribution on the outer edge of the cup were discussed based on the model. Simulation results indicate that the smaller the thickness of the spherical sealing cup, the greater the effect of the interference of the cup on the stress. And the thickness of the cup should not be too small, an example of the failure of pigging due to the small thickness of the cup and the increase in the interference is given. The conclusions obtained in this study can contribute to the optimization design of the PIGs.
Influence of Quenching-Tempering on the Carbide Precipitation of 2.25Cr-1Mo-0.25V Steel Used in Reactor Pressure Vessels
Authors: Wang Yafei , Hu Songyan , Cheng Guangxu , Zhang Zaoxiao , Zhang Jianxiao 
Published: November 2019

Abstract
The carbide precipitation of 2.25Cr-1Mo-0.25V steel is studied during the head-fabrication heat treatment process using gold replica technique, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and selected area electron diffraction (SAED). Shapes, structures and sizes of carbides before and after heat treatment are analyzed. The dissolution of strip-shaped carbides and the precipitation of granular carbides are confirmed. Amorphous films at the boundaries of carbides are observed by high-resolution transmission electron microscope (HRTEM), which is formed due to the electron irradiation under TEM.
Thermal Analysis of the 9977 Package Used for Nuclear Material Storage
Authors: Tamburello David , Kesterson Matthew , Hensel Steven 
Published: November 2019

Abstract
The 9977 is a US Department of Energy (DOE) shipping package used to transport plutonium bearing materials. The package utilizes a single 6 inch diameter containment vessel and a foam overpack to protect against fire and impact events. A storage facility fire, hotter and longer than the regulatory transportation fire, is evaluated to ensure radioactive material containment is maintained. A sensitivity analysis of foam degradation is also considered to conservatively simulate potential aging effects of the foam during storage. A minimum foam thickness needed to maintain containment during the hypothetical facility fire is determine.
A Framework for Underground Gas Storage System Reliability Assessment Considering Functional Failure of Repairable Components
Authors: He Lei , Wen Kai , Gong Jing , Wu Changchun 
Published: November 2019

Abstract
As one of the most important means of nature gas peak shaving and energy strategic reserving, the reliability assessment of underground gas storage (UGS) system is necessary. Although many methods have been proposed for system reliability assessment, the functional heterogeneity of components and the influence of hydrothermal parameters on system reliability are neglected. To overcome these problems, we propose and apply a framework to assess UGS system reliability. Combining two-layer Monte Carlo simulation (MCS) technique with hydrothermal calculation, the framework integrates dynamic functional reliability of components into system reliability evaluation. To reflect the state transition process of repairable components and their impact on system reliability, the Markov model is introduced at system level. In order to improve the calculation speed, artificial neural network model based on off-line MCS is established to replace the on-line MCS at components level. The proposed framework is applied to the reliability assessment and operation optimization of an UGS under different operation conditions. Compared with the traditional single-layer MCS method, the proposed method can not only reflect the variation of UGS reliability with hydrothermal parameters and operation time, but also can improve evaluation efficiency significantly.
Tuning of the Acoustical Analysis Model for Hypercompressors Through Strain Gage Pulsation Measurements
Authors: Fusi Andrea , Cappelli Leonardo , Carcasci Cosimo , Sacco Marco 
Published: November 2019

Abstract
Reciprocating compressor plants are typically exposed to vibrations, resulting from the discontinuity of the flow (pressure pulsations) and from external mechanical loads (compressor motion). To minimize the impact of pressure pulsations on vibration issues, a robust acoustical study is needed in the early design stage. Reliable standards and guidelines concerning vibration and pulsation are available for common applications (up to 350 bar) [1][2]. Within this pressure range it is possible to meet the standards by introducing pulsation suppression devices such as volume bottles or orifices. The Low-Density Polyethylene (LDPE) process requires very high pressures obtained with dedicated machines (Hypercompressors). There are no specific pulsation guidelines for these extreme pressures; in addiction reactive pulsation suppression devices like volume bottles are ineffective due to the high speed of sound in real gas (and related long wavelengths) at such pressures.
This paper describes the case history of a plant which exhibited high piping vibration from the first machine start-up. A survey was made to measure vibrations and pressure pulsations by means of strain gages: internal pressure was derived from external deformation through pressure vessel theory. Strain gages were chosen because they can be easily installed without positioning restrictions, while dynamic pressure sensors require pressure taps and must be limited to specific points.
Pulsation measurements were compared with an acoustic analysis, showing some discrepancy, especially at relatively high harmonics, mainly due to incorrect evaluation of the thermodynamic properties of high-pressure ethylene. In fact, in the LDPE process pressure range, isentropic exponent kv and compressibility factor Z can reach very high values, consequently affecting the calculation of the speed of sound.
A new acoustic modelling was developed to achieve better consistency with the measurements. Pressure-dependent kv and Z were taken into account and a sensitivity analysis of the most relevant valve parameters was performed.
Comparing the vibrations and pulsations spectra, once the MNF, compressor manifold arrangement and external loads are known, is fundamental to detect the origin of vibrations and how they are affected by pulsations.
Impact of Using ASME Section XI Code Case N-830 on Plant Heatup and Cooldown Pressure-Temperature Limit Curves for Pressurized Water Reactors
Authors: Carolan Alexandria , Mays Benjamin , Udyawar Anees , Hall J. Brian 
Published: November 2019

Abstract
Nuclear plant reactor pressure vessel heat-up and cool-down pressure temperature (P-T) limit curves are determined using ASME Section XI, Appendix G. ASME has adopted into ASME Section XI Appendix G the allowable use of the ASTM E1921 master curve fracture toughness based reference temperature (T0) to index the KIc curve. ASME Section XI Code Case N-830 allows the use of the KJc 95% lower bound master curve indexed using T0 directly. In ASME Section XI Appendix G, the equation RTT0 = T0 + 19.4°C, as an alternate RTNDT, shifts the KIc curve to approximate the KJc 95% lower bound master curve, however, the KIc exponential curve parameters are different. Thus, this paper evaluates the impact on plant heatup and cooldown pressure-temperature limit curves between the two ASME approved methods for typical pressurized water reactors (PWR). Different degrees of embrittlement are assessed to determine differences in the two approaches on reactor pressure vessel (RPV) beltline operating curves. Furthermore, in the proposed Revision 19 of Regulatory Guide 1.147, the US NRC has included a condition on the use of Code Case N-830 that prohibits the use of the current KIc equation in ASME Section XI Appendix G when these values are above the KJc lower bound 95% curve at temperatures below T0 − 64°C. This paper briefly discusses this NRC condition on the P-T limit curves.
The Influence of Multiaxial Stress Relaxation on Component Creep Damage Accumulation
Authors: Matev Nayden , Ainsworth Robert A. , Su Meini , Stevens Mark , Jappy Alan 
Published: November 2019

Abstract
Unless detailed inelastic analysis is utilised, high temperature codes base creep relaxation during a dwell period within a cycle on the start-of-dwell equivalent stress. The relaxation of the equivalent stress is then taken to be governed by a uniaxial creep law for the material being considered. Elastic follow-up is also included in such calculations. With this approach, only equivalent values of stress and creep strain rate are obtained and the stress multiaxiality is therefore assumed to remain at its initial value as the stress relaxes. Codes suggest that the stress drop is limited to a small fraction (typically 20%) of the initial equivalent stress to ensure that this assumption does not lead to significant inaccuracy. This paper reports creep relaxation results for a cruciform plate subjected to displacement-controlled biaxial loading. The initial biaxial loading ratio, the geometry of the cruciform plate and the value of the power in a power-law creep model are varied and these lead to variations in the elastic follow-up describing the creep relaxation. The biaxial stress ratio is generally found to change as relaxation occurs and a multiaxial ductility approach is used to evaluate the associated effect on creep damage accumulation. This is compared with the creep damage estimated by assuming relaxation is simply controlled by the equivalent stress with no change in multiaxial stress state during relaxation. For biaxial plane stress with one principal stress initially being negative, it is found that significant equivalent stress drops (up to about 40% of the initial value) can be allowed without the simplified equivalent stress approach becoming inaccurate. More care is required for positive stress biaxiality and the influence of multiaxial stress changes is found to depend on the initial stress biaxiality and the degree of elastic follow-up. The results will be used to propose improved guidance for simplified inelastic calculations.
A Review of Optimising the Design of a New Coke Drum Skirt
Authors: Berry Alex , Brown Warren , Seijas Antonio , Cook Sarah 
Published: November 2019

Abstract
Coke drums are subjected to severe thermal cycling with the skirt to shell connection weld being vulnerable to fatigue cracking. It is essential this connection is well designed to ensure a long life before repairs are inevitably required. Much has been written on coke drum skirt design with the aim of reducing the thermal stresses and strains encountered at the skirt connection weld, some designs have removed the weld completely allowing the drum to sit in an “egg-in-cup” arrangement. This paper includes a short literature review discussing Coke drum skirt designs and explains skirt behaviour during the drum cycle that results in eventual skirt cracking. A case study is reviewed in detail for a new pair of coke drums, where the predicted fatigue life of the chosen welded connection is assessed using axisymmetric, quarter symmetry and half symmetry finite element analysis supported by thermocouple data. The optimised design focuses on a conventional tangential design where the effects of the essential variables such as skirt thickness, skirt connection location, skirt-to head-gap and slot design (length, location & spacing) have been modelled and optimised to obtain a skirt design that produces the longest fatigue life for the intended duty cycle. Coke drum skirts must be installed onto the shell to exacting tolerances during manufacture to ensure concentricity and minimal gap between the skirt and shell. A brief overview of how this is achieved will be presented.
The Effects of Carburisation on Creep Response of Stainless Steel Components
Authors: Cakstins J. , Ainsworth R. A. , Su M. 
Published: November 2019

Abstract
Stainless steel components in the UK’s Advanced Gas-cooled Reactors can undergo microstructural changes near the surface due to the reactor carbon dioxide environment. Carburisation tends to increase the material’s elastic modulus, yield strength and creep resistance. However, the ductility of the material tends to be reduced. This paper assesses the effect on the component response of the changes in local elastic, plastic and creep material properties resulting from carburisation. A pressurised carburised cylinder is modelled analytically as a set of concentric, creeping homogeneous cylinders. The results show a reduced overall deformation rate in the steady state as expected. For completeness, it is shown quite generally that steady-state deformation in a creeping component is reduced by locally increased creep resistance. The cylinder model, however, shows that the locally increased creep and plastic resistance leads to higher stresses in the carburised region than in a homogeneous cylinder, particularly during the transition before steady-state conditions are established. The transient period before steady state creep is then examined in more detail numerically by allowing the material properties to change due to carburisation during the transient phase. This leads to reduced stresses in the carburised region. The influence of the results on deformation, triaxial stress fields and associated creep damage distributions are examined and used to provide guidance on both component assessment and on evaluation of carburised material properties from deformation measurements on test specimens.