Razvan George Ripeanu

Razvan George Ripeanu
Petroleum - Gas University of Ploiesti · Mechanical Engineering

PhD

About

74
Publications
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239
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Introduction

Publications

Publications (74)
Article
Full-text available
During transporting or raising processes any equipment used in petrochemical industry needs some special ears to be easy and safety manipulated. In the paper are presented some experimental results measured around some lifting ears welded on a cylinder. A special experimental device has been manufactured to complete the experiments. The acquisition...
Article
Full-text available
In the petrochemical industry there are many devices with cylindrical shapes such as: columns and horizontal or vertical vessels. All these devices, during the fitting or transporting processes must be raised using some special ears. Using the same methodology with those presented in [1,2,4,5], the paper presents the stresses that appear around som...
Article
Full-text available
In flanges, which operate at high temperatures and high pressures, such as in the petrochemical industry, relief of material stresses and thermal deformation are produced due to temperature increase, and as a result, the sealing pressure of the gasket is weakened, and leaks can occur. In this paper, using ANSYS 19.2, the tightening forces and torqu...
Article
Full-text available
In the case of well drilling interventions and repair operations, the specific installations must sometimes work for a longer period, of several weeks, during which severe weather conditions may appear. These include those in which high-speed winds occur, which influences the state of stress and displacements of masts, which are spatial constructio...
Article
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This paper aims to experimentally evaluate the wear and corrosion resistance of the coated active parts surfaces of a cut off valve. This paper presents the electrochemical corrosion, hardness and wear tests of the gate valve coated surfaces with a plastic material, in order to evaluate the seat and gate valve couple behaviour in an aggressive medi...
Conference Paper
Full-text available
The fix drilling equipments (masts) are the most important structure components from drilling rigs because support all the loads that appear during the drilling technological process. In order to ensure a safety behavior of the entire mast it is recommended that a proper calculation model to be completed. In the paper is presented a static and dyna...
Article
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The aim of this paper is to make a theoretical and experimental study to evaluate the water jet influence on a metallic material used in oilfield manufacturing, using AWJ process. It was investigated how the scattering of the jet has influenced the width of the kerf and neighboring area. The metallic material is P275NL2 which is a low temperature q...
Article
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The aim of this paper is to provide a method for modelling the influence of stray currents on buried pipes, using as calculation the boundary element method (BEM), using the module dedicated to corrosion in COMSOL Multiphysics software, which allows investigation both macroscopically and microscopically of corrosion processes. Dispersion currents,...
Article
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This paper aims to evaluate the erosion wear in coated valves where multiphase fluids containing oil and sand flow. Analysis models to evaluate the erosion rate of gate valves coated and uncoated with Everslik 1301 by using COMSOL Multiphysics 5.4 are presented. Also, based on these models, analysis results performed compare the erosion rates of co...
Article
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The present researches established the failure causes of the drill string, used in corrosive environments with H2S, in an oil field, by initiating fatigue cracks from the corrosion points on the inner surface of the drill pipes, which favoured the diffusion of hydrogen, the brittleness of the material and the brittle fracture.
Article
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Coiled tubing used in operational exploitation of oil and gas wells are made of special steels which have to resists to some special requirements such as: tensile strength, internal pressure resistance, collapsing resistance, fatigue strength, corrosion resistance and action of weakening factors. It is interesting that various producers are using d...
Article
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One of the methods used for the secondary exploitation of oil deposits is the water injection. The injected water is obtained after the separation of the well extracted fluid that contains a mixture of crude oil, water, gases and solid particles. Prior to injection, water must meet the following requirements: a high degree of purity obtained though...
Article
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Across the years there was an increased attention drawn by erosion modelling, both as a general approach and also towards pipeline applications (with a concentration on pipe bends). Several authors have studied the phenomena and tried to explain the mechanisms and factors affecting the emergence and magnitude of erosion. Most of the proposed models...
Article
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This study has the main objective the flow modelling using CFD through active parts waterjet cutting machine, model YCWJ-380-1520. More precisely, the study of flow through the cutting head and estimate the erosion wear caused by abrasion of these parts. The active parts of cutting head are the body of head, high pressure nozzle with jewel and mixi...
Article
Full-text available
In the paper is presented the working principle of the device as well as the constructive-functional scheme for its realization. The use of such a device allows variable gear ratios to be obtained in a very wide range. It has the advantage of a compact construction relative to other mechanisms with varying transmission ratios, such as the crank mec...
Article
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The aim of this paper is to make a research in order to analyze the modification of the microgeometry parameters of AWJ machined surfaces for a ductile material used in oilfield and petrochemical equipment. Experimental research was performed on waterjet cutting machine model YCWJ-380-1520 using pre-establish working conditions. The SURTRONIC 3+ de...
Article
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The heavy weight drill pipe, one of the most expensive components of the drill string, is exposed, beside fatigue and corrosion, to an intensive wear process as a result of the friction with the inner wall of the casing or the borehole wall, that lead to a drastically decrease of it durability. In order to improve the durability, the worldwide spec...
Article
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Gate valves, which are widely used in oil production and transportation processes, can be eroded by high fluid pressures and sand particles contained in crude oil during operation. This erosion can result in loss of valve thickness and shutdown of the operating system. Erosion is not uniform on valve elements, and it is different depending on the s...
Article
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The paper presents the results of the theoretical and experimental researches carried out for the evaluation of the corrosive rate of different equipment from water injection treatment plant used for water flooding. The degradation are occurring mainly at pipelines and connecting elements of the flotation skid, in the form of advanced corrosion wea...
Conference Paper
Full-text available
Flexible tubing (coiled tubing) demonstrated its capabilities and has been becoming nowadays a necessity in the oil and gas industry. Within the applications of flexible tubing have to be mentioned inclined drilling or horizontal drilling, cleaning clogged wells, interventions on wells both on production wells and during the drilling activities. Th...
Conference Paper
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If at first the non-circular wheels were treated as a hobby subject, their use now becomes ever larger. They are used in robotics, replacing cam mechanisms and lever mechanisms in the textile and agricultural industries. The paper presents a device used for the processing of non-circular gears, a device made according to my own design. For machinin...
Article
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Drill collars are special pipes used in the drilling of wells for weighting the drill bit, enabling it to drill through the rock. In the drilling process, the drill collars are exposed to an intensive wear due to friction on inner surface of casing wall. In order to evaluate the tribological behaviour of this friction couple, paper presents the dri...
Article
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Drill pipe is a seamless steel pipe with upset ends fitted with special threaded ends that are known as tool joints. During drilling operations, the wall thickness of the drill pipe and the outside diameter of the tool joints will be gradually reduced due to wear. The present research work investigate the possibility of reconditioning the drill pip...
Article
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Aluminum Nitride (AlN) has been long time being regarded as highly interesting material for developing sensing applications (including biosensors and implantable sensors). AlN, due to its appealing electronic properties, is envisaged lately to serve as a multi-functional biosensing platform. Although generally exploited for its intrinsic piezoelect...
Article
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The paper aims to find solutions to some of the problems the staff operating the natural gas networks have to face, which are the low, medium and high pressure, and the corrosion of the steel pipelines. This metal corrosion can be dealt with by insulating it through various procedures, the latest being the different thickness polyethylene strips in...
Article
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The new opportunities introduced by the large development of the IoT (internet of things) are increasing the demand for sensors to be located as close as possible to the supervised process. The Aluminum Nitride (AIN) is one of the most promising materials for sensors due to its piezoelectric, excellent mechanical properties, chemical inertness and...
Article
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Paper presents experimental results obtained by authors regarding pressure values and distribution, by using a special pressure sensitive paper, type FujiFilm and adequate hardware equipment and a soft program FPD810 Win. Was obtained the proper axial force related for different materials in order to respect the valves sealing demands. Were showed...
Article
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The main failures of heat exchangers are: corrosion of tubes and jacket, tubes blockage and failures of tube to tubesheet joints also by corrosion. The most critical zone is tube to tubesheet joints. Depending on types of tube to tubesheet joints, in order to better respect conditions of tension and compression, this paper analyses the tubesheet ho...
Article
Full-text available
During the exploitation process, the drill collars used in the petroleum industry are exposed to an intensive wear that leads to their rejection due to the material loss. Present paper brings forwards the technological procedure, established by the authors, for increasing the life time of the drill collars by applying a compensation material, using...
Article
Full-text available
Polyacrylamide is one of the most widely used and technically important organic water soluble polymer. The tribological and rheological characteristics of lubricant solutions based on polyacrylamide recommend this type of solutions for using as lubricants and metalworking fluids. For a better characterisation of lubricant solutions based on polyac...
Article
Full-text available
Polyacrylamide is one of the most widely used and technically important organic water soluble polymer. The tribological and rheological characteristics of lubricant solutions based on polyacrylamide recommend this type of solutions for using as lubricants and metalworking fluids. For a better characterisation of lubricant solutions based on polyac...
Article
The paper presents a synthesis of studies carried out to reduce wear in some petroleum dynamic equipment such as rod pumps and centrifugal pumps. Rod pumps and centrifugal pumps work in heavy conditions. Crude oil contains an important quantity of highly mineralized formation water, rich gases with a high percent of CO2, grains of sand from petroli...
Conference Paper
Full-text available
The paper contains the leading way to the torsion moment capable of assembly using the sectional closing bracelet. It is shown the calculation algorithm of the torsion moment capable of assembly using the sectional closing bracelet, and also its experimental definition. The assemblies using the sectional closing bracelet are used when frequently mo...
Conference Paper
Full-text available
During action, masts are the subject of various loadings that produce in their elements compression tensions or tensile. Using the finite element method there were determined the axial forces and bending moments in the masts elements for various types of loadings. It was established that in many of the masts elements (horizontal and diagonal) there...
Conference Paper
Full-text available
only for manuscript): Paper presents tests made by the authors in order to establish the wear and corrosion behavior of phosphatized and coated with a lubricant lacquer seat and gate active surfaces. Surfaces microgeometry, friction coefficient, wear rate and corrosion resistance were considered into account to evaluate the best technological solut...
Conference Paper
Full-text available
During the exploitation process, the drill collars used in the petroleum industry are exposed to an intensive wear that leads to their rejection due to the material loss. Present paper bring forward the technological procedure, established by the authors, for increasing the life time of the drill collars by applying a compensation material, using t...
Article
Full-text available
This paper contains some experimental results about erosion wear behavior of materials types AISI 304 and AISI316 gas and plasma nitrated. Thermochemical treatments parameters are presented, the metallographic structures obtained have been investigated, the hardness and thickness of stratums have been determined, and at wear tests developed in form...
Article
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The paper presents the influence of high velocity oxygen fuel (HVOF) parameters above hardfaced layers and the technological procedure established by the authors for hardfacing gate and seat at parallel side gate valves used in petroleum indus-try. The layer was characterised in order to fulfill the imposed working conditions including wear tests i...
Article
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The tribological behavior of different carbonaceous nanomaterials such as single wall carbon nanotubes (SWNTs), functionalized single wall carbon nanotubes (SWNTf), multiwall carbon nanotubes (MWNTs) and fullerene were investigated with a Pin on Disk friction and wear tester. The wear surfaces of the steel disk lubricated with the environmentally f...
Article
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Paper presents the studies made by the authors above the tube to tube sheet fittings of heat exchanger with fixed covers from hydrofining oil reforming unit. Tube fittings are critical zones for heat exchangers failures. On a device made from material tube and tube sheet at real joints dimensions were establish axial compression force and traction...
Article
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There are few experimental results available for the gas transmission pipelines and no experimental data have been found for distribution pipelines backfilled by subgrade. Paper presents the determination of loads due to backfill and loads due to live loads induced in gas pipes respecting the standard EN 13480-6:2004 methodology and in experimental...
Data
This paper describes the tribological behavior of Co-based single-wall carbon nanotubes (SWNTs) and a commercial antiwear (AW) and extreme-pressure (EP) additive to a mineral base oil (SAE 20). Single-wall carbon nanotubes possess interesting tribological properties; therefore, in our investigation, they were used as an AW and EP additive to SAE 20...
Article
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Austenitic stainless steels are largely used in cosmetic industry and not only. The biocompatibility and corrosion resistance of these materials are primarily determined by their constituent material and surface microstructural properties such as surface roughness, grain size, etc. The surface roughness and iron oxide layer thickness increase with...
Article
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Drilling draw-works drums are usually equipped with double and equilibrated band brakes. To assure the safely stop of the entire unload traveling block the friction coefficients of brake bands must be correctly established in conditions of working mediums. Paper presents the results of the tests made in order to determine the friction coefficient a...
Article
Materials Chemistry and Physics j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / m a t c h e m p h y s a b s t r a c t Zr/ZrCN multilayers, with bilayer periods ranging from 4.4 to 70 nm, were deposited on C45 and M2 steels and Si substrates by the cathodic arc technique, in a CH 4 + N 2 atmosphere. The elemental and...
Article
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AbstRACt tribo-thermal fatigue wear is a kind of degradation, which characterises the me-tallic element friction surface of the dry friction couples, like the heavy-duty me-chanical brakes, forging equipment, fire guns, etc. Frequently the durability of the heavy-duty mechanical brakes is firstly determined by the tribo-thermal fatigue wear, which...
Article
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abstraCt the gained knowledge in the study of nitriding and nitrocarburising processes during last years combined with the new developed methods and systems for pro-cess control now makes possible to perform reliable thermochemical technologies and gain efficiency in use of these for industrial applications. this paper shows the results of some res...
Article
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AbSTRACT The industrial activity in many fields implies the utilisation of middle alloy steels, which are subjected to cyclic non-isothermal stresses that characterise their func-tioning. Thus, can be enumerated some examples like: forging equipment, fire guns, chemical equipment, heavy-duty mechanical brakes, etc. The metallic struc-tures cyclic n...
Article
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In order to formulate new ecological metalworking fluids, the paper presents the tests made in first phase on universal tests machines as: ball-on-disk CSM micro-tribometer at different loads with 6 mm ball of 100Cr6 and the disks were made of carbon steel, in the presence of fluid samples with different complex esters and concentrations, in order...
Article
a b s t r a c t Nanocomposite Me–C–N:H coatings (Me is TiNb, TiZr or TiAl), with relatively high non-metal/metal ratios, were prepared by cathodic arc method using TiNb, TiZr and TiAl alloy cathodes in a CH 4 þ N 2 atmosphere. For comparison purposes, a-C–N:H films were also produced through evaporating a graphite cathode in a similar atmosphere. T...
Article
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ABsTrAcTs Paper presents different thin layers tribological proprieties established by Xrd diffraction, on pin-disk IT 10 made by the authors and on csm micro-tribom-eter in order to evaluate the friction coefficient and wear behaviour in dry conditions and the influence of bilayer period value. recent research has tried to use various plasma-based...
Article
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The aim of the paper is to present the results of experiments made by the authors in order to diminish erosion—corrosion wear at centrifugal pumps for petroleum industry. in electrolytic aggressive liquid media, such as crude oil, industrial or urban residual waters, the corrosive part of wear could be reduced, with low costs, by applying cathodic...
Article
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In petroleum industry, for different types of threaded connections, special lu-bricants with good adherence to the metallic surfaces are required. These lu-bricants must ensure adequate lubricating qualities to prevent galling during make up and break out, to allow the formation of a metal to metal sealing lu-bricating film, and an effective applic...
Article
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Sliding bearings in three cone bits are lubricated in heavy conditions. To improve tribological behavior, samples of bearings materials were made with implants of antifriction materials with different rapport between implant and free base material in the presence of different greases. Antifriction material has a greater dilatation coefficient than...
Article
TiAlZrCN superhard coatings, in which Ti and Al were additions to ZrCN base compound, were prepared by the cathodic arc method. The films were deposited on Si, plain carbon steel and high-speed steel substrates in a mixture of N 2 and CH 4 gases. Elemental and phase composition, chemical bondings, texture, surface roughness, hardness, adhesion, tri...
Article
In the last decade, considerable research effort was directed to the deposition of multilayer films with layer thicknesses in the nanometer range (superlattice coatings), in order to increase the performance of various cutting tools and machine parts. The goal of the present work was to investigate the main microstructural, mechanical and wear resi...
Article
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In order to formulate a new cooling oil lubricant for cutting, the paper presents the tests made on 4-balls machine on cooling fluids with different additive types and concentrations, in order to establish the proper composition. In the presence of selected cooling fluids, on Amsler machine, were determinate the tribological behavior of linear coup...