Corrosion Rate Of Steel Samples Research Articles

Effect of H2S on CO2 Corrosion of Mild Steel in High-Temperature Supercritical CO2 Conditions

The effect of H2S on the aqueous corrosion behavior of mild steel was evaluated at high-pressure and high-temperature (HPHT) conditions at a partial pressure of CO2 of 12 MPa and a temperature of 160°C. The corrosion rate of steel samples was determined by electrochemical and weight loss measurements. The surface and cross-sectional morphology and the composition of the corrosion product layers were analyzed by using surface analytical techniques (scanning electron microscopy, energy-dispersive x-ray spectroscopy, and x-ray diffraction). Results showed that the corrosion rate decreased with time and no significant difference was observed in the presence of 1,000 ppm and 2,000 ppm of H2S at HPHT CO2 conditions. Surface and cross-sectional analyses revealed that the corrosion process was governed by the formation of FeCO3 regardless of the presence of H2S. Furthermore, the corrosion behavior of mild steel in these conditions did not depend significantly on flow velocity.

Laboratory assessment of corrosion rate of carbon steel ground heat exchangers

Abstract. The materials used in the manufacture of geothermal heat exchangers for shallow geothermal applications play an important role in the overall system performance, especially if grout is not being used to seal the boreholes in which the heat exchanger is installed. The subject of this study is the durability evaluation of a vertical coaxial ground heat exchanger made of steel that is coupled directly to the ground. This solution minimizes the thermal resistance between the heat exchanger and the ground, but presents the important drawback of removing any protection toward the surrounding environment Among the materials proposed for manufacturing such vertical geothermal heat exchanger, carbon steel is suitable and have potential, due to its low cost and high thermal conductivity. The main disadvantage of this material is that it is strongly subject to corrosive attack, according to the chemo-physical properties of the underground. This study investigated the corrosion behaviour of carbon steel used in an experimental underground heat exchanger and assessed its durability over time. Corrosion rate of steel samples were measured in the laboratory by weight loss method after exposure over a specified period in a selected ground medium. Different ground conditions were tested, resulting in different densities and moisture contents of ground samples collected on the field. Based on the results, the corrosion rate of carbon steel is evaluated as a function of water content and rate of ground compaction. This information has allowed to advance more accurate quantitative forecast of the expected operational life of installed geothermal exchangers and their safety over time.

Analysis of Environmental Factors Affecting the Atmospheric Corrosion Rate of Low-Alloy Steel Using Random Forest-Based Models.

As one of the factors (e.g., material properties, surface quality, etc.) influencing the corrosion processes, researchers have always been exploring the role of environmental factors to understand the mechanism of atmospheric corrosion. This study proposes a random forest algorithm-based modeling method that successfully maps both the steel’s chemical composition and environmental factors to the corrosion rate of low-alloy steel under the corresponding environmental conditions. Using the random forest models based on the corrosion data of three different atmospheric environments, the environmental factors were proved to have different importance sequence in determining the environmental corrosivity of open and sheltered exposure test conditions. For each exposure test site, the importance of environmental features to the corrosion rate is also ranked and analyzed. Additionally, the feasibility of the random forest model to predict the corrosion rate of steel samples in the new environment is also demonstrated. The volume and representativeness of the corrosion data in the training data are considered to be the critical factors in determining its prediction performance. The above results prove that machine learning provides a useful tool for the analysis of atmospheric corrosion mechanisms and the evaluation of corrosion resistance.

Using Dry Olive Leaves for Oil Pipes Corrosion Inhibitor

At the present time the use of corrosion inhibitors is a good solution to maintain or reduce the corrosion problems in the equipment, so nowadays the production of inhibitors all non-toxic, natural and cheap is the most important demand. In this study dry olive leaves extraction used as inhibitor in a temperatures similar to the average temperature in Iraq, so as to bring the picture of reality as much as possible, at (25 °C and 45 °C) and solution was prepared in the following concentration to stimulate the field environment for oil extracting 19.2 % of sodium chloride (NaCl), 8% of calcium chloride (CaCl), 1.08 % of magnesium chloride (MgCl) and saturated with Co2 gas, the corrosion rate of steel sample was measured be using a potentiostat device with reference of calomel electrode. The result was, the dry olive leaves extract is an effective inhibitor material. Dry olive leaves extraction inhibitor has a low corrosion rate at 25OC and 45OC and the Corrosion rate decrease with increasing temperature for oil extraction solution, From the EDS test found that high percentage of carbon and oxygen caused to produce many compounds like the phenolic compound of the olive leaves is the responsible of inhabitation effect of the olive leaves.

Using Dry Olive Leaves for Oil Pipes Corrosion Inhibitor

At the present time the use of corrosion inhibitors is a good solution to maintain or reduce the corrosion problems in the equipment, so nowadays the production of inhibitors all non-toxic, natural and cheap is the most important demand. In this study dry olive leaves extraction used as inhibitor in a temperatures similar to the average temperature in Iraq, so as to bring the picture of reality as much as possible, at (25 °C and 45 °C) and solution was prepared in the following concentration to stimulate the field environment for oil extracting 19.2 % of sodium chloride (NaCl), 8% of calcium chloride (CaCl), 1.08 % of magnesium chloride (MgCl) and saturated with Co2 gas, the corrosion rate of steel sample was measured be using a potentiostat device with reference of calomel electrode. The result was, the dry olive leaves extract is an effective inhibitor material. Dry olive leaves extraction inhibitor has a low corrosion rate at 25OC and 45OC and the Corrosion rate decrease with increasing temperature for oil extraction solution, From the EDS test found that high percentage of carbon and oxygen caused to produce many compounds like the phenolic compound of the olive leaves is the responsible of inhabitation effect of the olive leaves.

Anodic Polarization Behavior of X80 Steel in Na₂SO₄ Solution under High Potential and Current Density Conditions.

X80 steel has great risk of corrosion in high voltage direct current (HVDC) interference cases. In this study, the anodic polarization behavior of X80 steel under high potential and current density in Na2SO4 solution was investigated. The I × R drop was eliminated using current interrupt technique during the potentiodynamic measurement. Therefore, the real polarization curve was obtained. The corrosion behavior was investigated by galvanostatic polarization, scanning electron microscopy, and X-ray photoelectron spectroscopy. The results show a new form of passivation route. The steel dissolved actively below −0.388 VSCE, then became partly passivated from −0.388 to 1.448 VSCE, and fully passivated above 1.448 VSCE. The passive film was formed containing Fe2O3 and FeOOH, and resistant to SO42− ions. It not only blocked the direct dissolution of steel, but also facilitated oxygen evolution. The corrosion rates of steel samples decreased after the passivation.

A comprehensive predictive corrosion model incorporating varying environmental gas pollutants applied to wider steel applications

A comprehensive model has been developed to predict uniform corrosion rate of structural steel under the effect of low pH conditions for example, acid rain. Acid rain is mainly caused by emissions of sulphur dioxide (SO2) which reacts with the water droplets in the atmosphere to produce acidic solution which is the primary cause of corrosion of steel structures such as bridges, high value assets, weathering of stone buildings and statues. A five-stage approach was applied to mathematically describe the model as: (i) the growth rate of air-suspended water droplets (i.e. moisture) depending on the condensation/evaporation rate, (ii) the absorption of gas phase SO2 in the droplets forming bisulfite HSO3− ions, (iii) the coalescence of these SO2 absorbed water droplets under the effects of wind speed and gravity, (iv) the deposition rate of SO2 absorbed droplets on steel substrate depending on the inclination and azimuth angles of steel surfaces and, (v) the corrosion rate of steel due to the deposition of these SO2 absorbed droplets. The incorporation of all of the above stages develops a comprehensive corrosion prediction model which includes both the electrochemical parameters and large number of physical, environmental and material parameters. Experiments were performed to analyse the corrosion rate of steel samples by exposing them to moist SO2 corrosion test. A comparative analysis between the modelled predictions and experimental results was performed to verify the reliability of the model. The predictive trends of corrosion rate of steel were also generated for various values of temperature, relative humidity and SO2 mole percentage. This research provides design solutions and guidelines against degradation due to aggressive application environments. Enhanced corrosion resistivity within large structures, installations, automotive, locomotives, aerospace and building with historic biography will aid longevity and cost savings.

The effect of sulphide and moisture content on steel corrosion during transport of fine wet coal

In the present investigation the influence of compaction pressure (stress) on the corrosivity of wet coal was investigated. Two coal samples, one high in sulphur content (3 %) and the other low in sulphur content (0.6 %) were used to determine the influence of compaction stress on the corrosion rates of steel samples in contact with compacted coal. It was found that the pressure exerted on finely divided wet coal is an important factor in determining its water content and corrosivity towards mild steel. Corrosion of the steel was typically in the form of pitting and the sulphur content of the coal was an important factor in determining the corrosivity of the coal. The corrosion rate of the high sulphur content coal was higher than that of the low sulphur coal. Mossbauer spectroscopy showed that a FeS species developed on the steel surface.

Initiation and evolution of corrosion phenomena on steel in neutral chloride media

The aim of our study is to investigate in a methodical way the influence of the three following parameters: surface initial preparation, nature of electrolyte, hydrodynamic conditions, on the evolution of both free corrosion potential “E corr” and limiting diffusion current i L of oxygen reduction, for two different kinds of steel samples in neutral chloride media. During the first hours of the beginning of corrosion phenomena, steel behaviour is dependent on the evolution of corrosion ratio. The determination of instantaneous corrosion rates of steel samples, involving fast electrochemical techniques, always needs a preliminary survey in order to make sure of the validity of the experimental results.