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Hydrogen Sulfide Corrosion of Weld Regions in API X52 Steel  [PDF]
Arenas-Martínez L.F,García-Cerecero G.
Ingeniería, investigación y tecnología , 2012,
Abstract: The corrosion behavior of gas metal arc welding (GMAW) regions has been studied using potentiodynamic polarization and polarization resistance (LPR) techniques. Experiments were conducted in hydrogen sulfide (H2S)-containing brine and in H2S-free brine. Welds were made on API 5L X52 steel. Due to differences in their microstructure, chemical composition and residual stress level, weld regions exhibited different responses under H2S corrosion. Base metal exhibited the highest corrosion rate (CR) and the most cathodic corrosion potential.
Estudio del da o por hidrógeno en uniones soldadas de un acero API 5L X52
Réquiz, R.,Camero, S.,Aristizabal, V.,Rivas, A.
Revista de Metalurgia , 2008,
Abstract: The main objective of the present investigation was to study the susceptibility to hydrogen damage on a type API 5L X52 steel welded by electrical resistance. Several techniques, such as hydrogen permeation and cathodic charging were used. The metallic material was characterized using SEM and TEM. The base metal microstructure was very similar to that one corresponding to the welded area. This microstructure was mainly comprised by ferrite and perlite, differing only in the grain size. Therefore, the susceptibility to hydrogen damage was similar in both cases. It is worth mentioning that the welded area has very small dimensions. Indeed, the fusion zone is only 5 mm wide while the heat affected zone is 1 mm wide. The hydrogen damage observed was mainly in the form of blisters, which were associated to the presence of aluminum rich inclusions. Also, it was noticed partial inclusion dissolution and some matrix attack adjacent to the inclusions. En la presente investigación se estudió la susceptibilidad al da o por hidrógeno en un acero API 5L X52 soldado por resistencia eléctrica. Para ello, se emplearon técnicas de permeación y de carga catódica de hidrógeno. El material fue caracterizado mediante microscopía electrónica de barrido y de transmisión. La susceptibilidad al da o por hidrógeno fue similar tanto en el metal base como en el cordón de soldadura. Este comportamiento se vincula a la microestructura homogénea constituida por perlita y ferrita, que presentan ambos, aun cuando existen diferencias en el tama o de grano. El cordón de soldadura tenía dimensiones muy peque as, donde la zona de fusión y la afectada por el calor poseen espesores de 5 mm y 1 mm, respectivamente. El da o inducido por hidrógeno se presentó en forma de ampollas en la superficie del material, asociado, principalmente, a la presencia de inclusiones globulares y semiglobulares ricas en aluminio. Además, se manifestó una disolución parcial de las inclusiones y/o un ataque de la matriz en la zona adyacente a la inclusión.
Evaluation of Stress Corrosion Cracking Damage to an API 5L X52 Pipeline Transporting Ammonia: A Case Study  [PDF]
José Luis Mora-Mendoza, Mónica Jazmín Hernández-Gayosso, Daniel Antonio Morales-Serrat, Octaviano Roque-Oms, Digna Alejandra Del Angel, Gerardo Zavala-Olivares
Materials Sciences and Applications (MSA) , 2016, DOI: 10.4236/msa.2016.710050
Abstract: The high number of leak events that took place in recent years at a 25.4 cm (10”)Ø pipeline transporting anhydrous liquid ammonia, located in the Southeast of Mexico, was the main reason to carry out a number of field studies and laboratory tests that helped establish not only the failure causes but also mitigation and control solutions. The performed activities included direct evaluation at failure sites, total repair programs, metallographic studies and pipeline flexibility analyses. The obtained results were useful to conclude that the failures obeyed a cracking mechanism by Stress Corrosion Cracking (SCC) which was caused by the combined effect of different factors: high stress resistance, high hardness of the base metal with a microstructure prone to brittleness and residual strains originated during the pipeline construction. From the operative, logistic and financial standpoints, it is not feasible to release the stress of approximately 22 km of pipeline. Therefore, the only viable solution is to install a new pipeline with suitable fabrication, construction and installation specifications aimed at preventing the SCC phenomenon.
Effect of an Imidazoline [IM–NH17] on the Corrosion Process of API5l–X52 Steel Exposed in Acidified Brines  [PDF]
A.G. Reynaud–Morales,M. Casales–Díaz,J.G. Chacón–Nava,L. Martínez–Gómez
Ingeniería, investigación y tecnología , 2009,
Abstract: The inhibition effect of an aminoethyl oleic imidazoline [IM–NH17]) on the corrosion of API5L–X52 steel in acidified 5% NaCl pH 3 solutions at 50°C was studied via electrochemical methods, i.e. potentiodynamic polarization tests and linear polarization resistance measurements. Polarization curves revealed that, under the test conditions, the inhibitor performs as a mixed type inhibitor. Linear Polarization Resistance measurements showed an increase in Rp values for inhibitor containing solutions as compared with the blank solution. The results revealed that the inhibitor efficiency increases with inhibitor concentration in the range from 12.5 ppm to 25ppm. From the electrochemical results, it was found that the adsorption mechanism that better fits the present system follows the Langmuir isotherm model.
Sweet Corrosion Inhibition on API 5L-B Pipeline Steel  [PDF]
Mahmoud Abbas Ibraheem,Abd El Aziz El Sayed Fouda,Mohamed Talaat Rashad,Fawzy Nagy Sabbahy
ISRN Metallurgy , 2012, DOI: 10.5402/2012/892385
Abstract: Corrosion inhibition and adsorption behavior of two triazole derivatives on API 5L-B carbon steel in CO2-saturated 3.5% NaCl solutions was investigated using potentiodynamic polarization, EIS, and EFM techniques. Specimen surfaces were characterized using SEM, EDX, and XRD. Results show that the two compounds are mixed-type inhibitors and inhibition efficiency increases with increasing concentrations. Adsorption of the two compounds chemisorption and obeys Langmuir adsorption isotherm. Activation energy and thermodynamic parameters were calculated. Surface analyses confirm the formation of iron nitrides on the metal surface which supports results obtained from previous techniques. 1. Introduction Carbon dioxide which is present naturally in oil and gas wells is injected purposely into wells to enhance oil recovery. CO2 corrosion, also known as “sweet corrosion,” is one of the major problems in oil and gas industry, costing billions of dollars every year. Great efforts must be expended in corrosion control for safety, business, and environmental considerations. Sweet corrosion is caused by the presence of carbon dioxide (CO2) dissolved in water to form carbonic acid (H2CO3). Corrosion increase as the concentration of CO2, system pressure, and temperature increase. This corrosion is typically slow, localized and results in pitting attack. Pits are very difficult to detect because of their tiny size and the corrosion products that cover them. In oil and gas production and processing industries, corrosion inhibitors have always been considered the first line of defense against internal corrosion. Inorganic inhibitors, such as sodium arsenite (Na2HAsO3) and sodium ferrocyanide, were used in early days to inhibit carbon dioxide (CO2) corrosion in oil wells, but the treatment frequency and effectiveness were not satisfactory. This led to the development of many organic chemical formulations that frequently incorporated film-forming amines and their salts. In this work, the corrosion inhibition and adsorption behavior of Itraconazole and Fluconazole compounds on API 5L-B carbon steel in CO2-saturated 3.5% NaCl solutions was investigated using potentiodynamic polarization, electrochemical impedance spectroscopy, and electrochemical frequency modulation techniques. The surfaces of the samples were characterized using SEM, EDX, and XRD techniques. The effect of temperature on the corrosion rates and inhibition process was also investigated. 2. Experimental 2.1. Materials Preparation Experiments were conducted using a conventional three-electrode 200?mL cell
Comportamiento de Laminaciones Coplanares y No Coplanares en Acero API5L X52 Simuladas mediante Elementos Finitos
Servin,Alberto; González,Jorge L; Morales,Alfredo;
Información tecnológica , 2009, DOI: 10.4067/S0718-07642009000500013
Abstract: the mechanical behavior of the coplanar and non coplanar laminations by finite element using non lineal material conditions was determined, with the purpose of knowing the interaction sequence of the stress fields in the crack tips. the analysis includes a matrix simulation considering the circumferential length lamination, wall thickness of the pipe 610mm diameter, with vertical and horizontal distance for non coplanar laminations. the stress distribution in the laminations regions as a function of the internal pressures in the cracks and pipe were determined. the simulations done allowed defining the yield and the strength pressure that reach the mechanical properties of the api 5l x52. it was found that coplanar laminations with 24 at 127mm of circumferential length resist 50% more yield pressure than the non coplanar laminations and 100% more pressure than the maximum allowable. based in the plots of pressure -vs- lamination radius it is concluded that non coplanar laminations have higher cracking risk in the pipeline.
Comportamiento de Laminaciones Coplanares y No Coplanares en Acero API5L X52 Simuladas mediante Elementos Finitos Behavior of Coplanar and Non-Coplanar Laminations in API5L X52 Steel Simulated by Finite Elements  [cached]
Alberto Servin,Jorge L González,Alfredo Morales
Información Tecnológica , 2009,
Abstract: Se determina el comportamiento mecánico de laminaciones simples y escalonadas modeladas por elementos finitos en condiciones no lineales de esfuerzo-deformación, para comprender la secuencia de la interacción de los campos de esfuerzos en los extremos de la grietas. Se estableció una matriz de simulación variando la extensión circunferencial de las laminaciones, con espesor del tubo de 610mm de diámetro, con separación vertical y horizontal para el caso de laminaciones escalonadas. Se determino la función de distribución de esfuerzos en la región de las laminaciones en función de la presión en la grieta y en el tubo. Se estableció la presión que origina alcanzar la cedencia y resistencia ultima del material API5L X52, determinando que las laminaciones simples cuya extensión circunferencial va de 24 a 127 mm, soportan 50% más de presión de cedencia que las laminaciones escalonadas, y el 100% más de presión máxima permisible. Basados en la graficas presión versus radio de las laminaciones se concluye que las laminaciones no coplanares representan mayor riesgo de agrietamiento en una tubería. The mechanical behavior of the coplanar and non coplanar laminations by finite element using non lineal material conditions was determined, with the purpose of knowing the interaction sequence of the stress fields in the crack tips. The analysis includes a matrix simulation considering the circumferential length lamination, wall thickness of the pipe 610mm diameter, with vertical and horizontal distance for non coplanar laminations. The stress distribution in the laminations regions as a function of the internal pressures in the cracks and pipe were determined. The simulations done allowed defining the yield and the strength pressure that reach the mechanical properties of the API 5L X52. It was found that coplanar laminations with 24 at 127mm of circumferential length resist 50% more yield pressure than the non coplanar laminations and 100% more pressure than the maximum allowable. Based in the plots of pressure -vs- lamination radius it is concluded that non coplanar laminations have higher cracking risk in the pipeline.
Fragilización por Hidrógeno de los Aceros API 5L X60 y API 5L X80 Hydrogen Embrittlement of API 5L X60 and API 5L X80 Steels  [cached]
Bruno A Araújo,Jorge A Palma,Eudésio O Vilar,Antonio A Silva
Información Tecnológica , 2011,
Abstract: Se ha determinado el comportamiento mecánico de los aceros API 5L grados X60 y X80, fragilizados por hidrógeno ambiental y por hidrógeno interno. El potencial y la densidad de corriente para la generación del hidrógeno fueron determinados por polarización potenciodinámica, y el tiempo de saturación estimado a partir de datos de difusividad y solubilidad obtenidos en ensayos de permeación con una célula electroquímica. La carga de hidrógeno para reproducir las condiciones de la fragilización por hidrógeno ambiental y fragilización por hidrógeno interno fue realizada generando un gradiente de concentración para el primer caso, y generando gradientes de concentración y de tensiones para el segundo. Luego de los ensayos de tracción se verificò que, en las condiciones definidas en este trabajo, el modo de fractura en ambos tipos de fragilización fue predominantemente dúctil. Ademàs, los dos aceros mostraron una susceptibilidad baja o moderada a la fragilización por hidrógeno ambiental, no siendo susceptibles a la fragilización por hidrógeno interno. The mechanical behavior of the API 5L X60 and X80 grade steels under environmental hydrogen embrittlement effect and internal hydrogen embrittlement effect was determined. The potential and current density for hydrogen generation were determined by potentiodynamic polarization. The saturation time was estimated from diffusivity and solubility data, obtained from permeation tests with an electrochemical cell. The hydrogen charge to reproduce the conditions of the environmental hydrogen embrittlement and the internal hydrogen embrittlement was performed by generating a concentration gradient in the first case, and a concentration and stress gradients in the second case. After the tensile tests it was verified that in the defined tests conditions, the fracture mode in both types of embrittlement was predominantly ductile. Also, both steels showed low or moderate susceptibility to environmental hydrogen embrittlement, not being susceptible to internal hydrogen embrittlement.
Corrosivity of H2S-producing bacteria isolated from formation waters used in secondary crude-oil recovery
Duque,Zoilabet; Chicote,Eduardo; Sarró,M. Isabel; Moreno,Diego A; de Romero,Matilde F; Pérez,Orlando A;
Revista Técnica de la Facultad de Ingeniería Universidad del Zulia , 2004,
Abstract: there have been problems in the water-injection systems of the oil industry due to microbiologically induced corrosion (mic), associated with the presence of sulphate-reducing bacteria (srb), which produce h2s. several investigators consider that this is the principal cause of bacterial corrosion in natural-water storage and distribution systems. given the fact that other groups of bacteria are not considered in current microbiological treatments and controls, it would be useful to investigate the presence of other anaerobic microorganisms that produce this aggressive metabolite or its derivatives in water-injection systems. this article reports on srb and non-srb strains isolated from injection systems and identified by dna sequencing, among them, desulfovibrio termitidis (srb) and escherichia coli (non-srb). evaluation of the activity and corrosivity of the two types of bacteria indicated that there was a significant difference in activity in the selective media, mainly that sulphide generation by the sulphate dissimilation process is much greater than that of the group that generates it by fermentation, as well as corrosivity on the carbon steel api 5l grade x65, as determined by open circuit potential, polarization resistance and weight loss during 60 hours? evaluation in selective media with no ferrous salts. nevertheless, scanning electron microscopy indicated biofilm development and localized attacks on the steel by both types of bacteria, which confirms the need for investigating and considering the role of these non-srb anaerobic groups so as to exercise better control over bacterial corrosion.
Measurements of the Thermophysical Properties of the API 5L X80  [PDF]
Tiago de Sousa Antonino, Pablo Batista Guimar?es, Roberto de Araújo Alécio, Yogendra Prasad Yadava, Ricardo Artur Sanguinetti Ferreira
Materials Sciences and Applications (MSA) , 2014, DOI: 10.4236/msa.2014.58064
Abstract:
The thermophysical properties of API 5L X80 steel were experimentally measured, in order to use these in computational models to determine the temperature field in welded joints. In this work, values of thermal expansion coefficient, specific heat, thermal diffusivity and thermal conductivity were experimentally obtained as a function of temperature. The thermal expansion coefficient was determined at temperatures of 20°C to 1200°C in a dilatometer DIL 402 PC. The specific heat was determined on a differential scanning calorimeter at temperatures between 300°C and 1200°C. The diffusivity and thermal conductivity were determined in the temperature range 100°C to 800°C in a 457 LFA diffusivimeter using laser flash technique. The thermal expansion coefficient remained approximately with constant value of 8.5 × 10-6 K-1 and suffered two falls reaching values -25 × 10-6 K-1 and -50 × 10-6 K-1 in the stages of heating and cooling respectively. It was observed for this material, minimum and maximum values of specific heat equal to 0.571 J/gK and 1.084 J/gK at temperatures of 300°C and 720°C, respectively. The behavior of thermal diffusivity and thermal conductivity in the temperature range 100°C to 800°C tends to decrease with increasing temperature. Based on the measured properties, computational modeling of the temperature field can be numerically obtained with better accuracy.
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