Papers by Keyword: Corrosion Rate

Abstract: AISI 304 is widely used as biomedical material due to its lower cost and availability, but low corrosion resistance. The shot peening method can increase the mechanical characteristics and corrosion resistance of a surface. The purpose of this study was to determine the effect of shot peening surface treatment with a combination of steel ball diameter variations and pressure on corrosion resistance of AISI 304 material. Shot peening treatment was carried out using variations of 0.2, 0.5, and 0.8 mm steel ball diameters with a hardness of around 40-50 HRC. Shot peening pressure varies from 7, 8, and 9 bar. Corrosion rate testing was carried out using bovine serum media. The results showed that the best increase in corrosion resistance was 0.117 mpy for a steel ball diameter of 0.5 mm with a pressure of 9 bar, 3 times lower than that of non-treated specimens, which was 0.378 mpy.

Abstract: The paper considers methods for calculating the rate of metals corrosion. A comparative analysis of the experimental data on the steel 10 corrosion rate in carbonate solutions with different pH values (6-12.5) and the concentration of carbonate ions on the disk electrode made of steel 10. The calculation of the corrosion rate by the gravimetric method and the method of polarization resistance is carried out. A detailed description of the calculating the corrosion rate stages index from experimental electrochemical data (I-E) obtained on the potentiostat IPC PRO is given. The advantages and disadvantages of the considered methods are indicated.

Abstract: The objective of this study is to carry out an atmospheric corrosion analysis on low carbon steel in the form of plates and elbows in the port area of Belawan. The exposure of the test specimen was carried out at five locations for 12 months. The location points are notated as A, B, C, D, and E. The process of specimen exposure and data collection followed the ASTM G-1 and ASTM G-50 standards. The measurement results indicated a slight difference in the corrosion rate at each location. Location C and D have the highest corrosion rate and location A has the lowest corrosion rate. Meanwhile, for locations B and E have a corrosion rate value that is not much different from location A. This difference in value is probably a consequence of the distance from the exposure location to the seaside. Locations C and D are adjacent to the seaside while the other locations are not. The steel plate has an average value of corrosion rate 0.2214 mpy and steel elbow has a rate of 0.2412 mpy. From the measurement results obtained, the two specimens exposed at each location are still in the "outstanding" category.

Abstract: Piping systems at gathering stations in the oil and gas industries often fail due to corrosion attacks from the brine water solution containing 8% NaCl that flows through the system. This solution is highly corrosive on the API 5L grade B steel pipes, thereby shortening its lifespan, with an increase in the frequency of pipe replacements. However, the corrosion resistance of API 5L grade B pipes can be improved by using chromate and molybdate inhibitors. Therefore, the objective of this research is to improve the corrosion resistance of the steel pipes using sodium chromate (Na₂CrO₄) and sodium molybdate (Na₂MoO₄) inhibitors with concentrations of 0.2, 0.4, 0.6, 0.8 and 1,0%. This research also aim to determine the optimum concentration of inhibitors to produce minimum corrosion rate, by testing the brine water solution containing 8% NaCl through the potentiodynamic polarization method. The results show that generally, the addition of sodium chromate and sodium molybdate inhibitors to the brine solution causes the steel pipes to be more resistant to corrosion. Furthermore, the sodium chromate inhibitor concentration of 0.6% produces the greatest corrosion potential of – 400 mV with the lowest rate of 0.38 mpy, while sodium molybdate concentration of 0.4% produces the highest corrosion potential of – 385 mV with the lowest rate of 0.34 mpy. The results of SEM observations at 0.4% sodium molybdate concentration showed that the corrosion inhibition/passivation effect of the inhibitor made the steel surface smoother, while the sodium chromate inhibitor at similar percentage failed to reach the optimal concentration to inhibit the corrosion process.

Abstract: This research examined the corrosion inhibition potency of inhibitive Ibuprofen drug (IID)on aluminium 6063. The effect of the inhibitive drug was tested in 0.5 M of H2SO4 solutionusing potentiodynamic method. The concentration of IID was mixed to the acidic mediumin 0, 5, 10, 15 and 20 ml respectively. The polarization experiment shows IID adsorbed onaluminium specimens. Increase in IID concentration decreases corrosion rate of aluminiumspecimens. Maximum inhibitive efficiency of 80.58 % and further studies on the inhibitoryeffect of the drug inhibitor revealed that Freundlich isotherm displayed a regressioncoefficient value of 0.7893 while Langmuir isotherm exhibits a regression coefficient valueof 0.8864. These values of regression establish the reliability of IID as inhibitor, whichshows that IID can be used as inhibitor corrosion of aluminium in aggressive environmentsuch as marine and petrochemical industries where protection of aluminium is a necessity.

Abstract: Currently, inhibitory protection is one of the most effective and common methods of protecting the inner surface of oil field equipment from corrosion. The work explores the mechanism of protective action of new inhibitors based on quaternary ammonium compounds and assesses feasibility of their practical application in oil fields of OJSC Surgutneftegas. Studies were conducted on samples made of pipe steels A 568M, A 516-55 and 13CrV (rus 13ХФА) in a model produced water solution. Three corrosion inhibitors were tested. Parameters of the mechanism of protective action of reagents were determined by potentiodynamic analysis.

Abstract: Aspects of the development of local corrosion on the metal surface under the influence of aggressive media containing chloride ions are presented. The main mechanisms leading to the formation and development of local damage of the surface of metals are described. The process of electrochemical corrosion of steel under the influence of chloride-containing medium is experimentally investigated. By constructing corrosion diagrams, the main indicators of steel corrosion in a 10% sodium chloride solution were determined, which allows one to judge the rate of development of corrosion processes with local damage to the protective coating and the degree of steel resistance depending on the aggressiveness of the medium. It is shown that protective coatings, such as modified phosphate and oxide-phosphate films, prevent the penetration of an aggressive medium to the surface of the protected metal and, accordingly, the anodic dissolution of the metal.

Abstract: Even though carbon steel is susceptible to corrosion degradation, carbon steel is widely used for applications in the industry. Impurities in steel composition are known to affect the mechanical and corrosion properties. There are many studies on the corrosion of steel, but for a specific application, further research still required. The present work is conducted to determine the effect of low concentration of sulfuric acid on the corrosion rate of power plant steel ASTM A213-T12 with a solution concentration from 0.01-0.05 M H₂SO₄. The corrosion rate was determined by using an immersion test as well as a polarization method using a potentiostat. The result shows that increasing the concentration of sulfuric acid molarity, the corrosion rate tended to increase. Furthermore, the effect of phosphor contents significantly affects the corrosion rate in which steel with high phosphor contents has a high corrosion rate.

Abstract: In order to determine the inhibitory additives concentration influence degree on the corrosion degradation rate, we studied the anode behavior of steel reinforcement made of steel grade St3 in a 10% solution NaCl with and without the inhibitors additives of various concentrations. As inhibitory additives, nitrates of potassium, sodium, magnesium, calcium and zinc were introduced into the aggressive environment, since they are often introduced into concrete compositions to accelerate their hardening. Polarization curves have been obtained for steel reinforcement in an aggressive environment, allowing the corrosion rate calculation. It was established that the introduction of potassium and zinc nitrates in an amount of 0.5% into an aggressive environment has the greatest effect on the corrosion processes’ inhibition. When nitrates of alkali and alkali-earth metals are introduced into an aggressive environment, the change in the reinforcing bars mass made of St3 steel occurs 7-8 times slower. Increasing the concentration to 1 and 1.5% is shown to be impractical, due to the small difference in the effect on the reinforcing steel anodic dissolution. A study on the effect of combining inhibitory additives on the corrosion resistance of steel reinforcement in a 10% solution NaCl was made. It was found that the combined action of inhibitors is less effective than the single effect of additives on the corrosion rate.

Abstract: Conversion coating in metal material was a method to control the corrosion. It applied in parts of car, aircraft, factory installation, and other appliances. There were three types of conversion coating: phosphate conversion coating, chromate conversion coating, and oxalate conversion coating. There were several aspects to consider in controlling the corrosion fully. This research used phosphate because phosphate conversion coating had a low corrosion rate, affordable production cost, and environmentally friendly. This research aimed to find out the corrosion resistance of ST37 carbon steel using phosphate conversion coating in various immersion durations. Therefore, the result was a breakthrough in using phosphate conversion coating for the industries. This research used the weight loss method to calculate the corrosion rate and macro photos to obtain the corrosion form during the test. This research used ST37 carbon steel with 100 mm x 30 mm x 10 mm as the specimen and phosphate with various coating durations (10, 20, and 30 minutes). Each variation had three specimens, so this research had nine specimens in total. This research calculated the daily corrosion rate for seven days using 5% NaCl as the corrosion solution. The average corrosion rate in specimens with 10 minutes duration was 1.9599 mpy, specimens with 20 minutes immersion was 1.7647 mpy, whereas specimens with 30 minutes duration were 1.3287 mpy. Thus, the longer immersion duration created a smaller corrosion rate. Also, the corrosion formed during the test was pitting and uniform corrosion.