• Corrosion Science and Technology
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• v.17 no.5
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• pp.249-256
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• 2018

Metallic structures in the oil and gas production undergo severe degradation due to sweet and sour corrosion caused by the presence of $CO_2$ and $H_2S$ in the fluid environment. The corrosion behavior of 304 austenitic stainless was investigated in the presence of varying concentrations of $CO_2$ or $H_2S$ and $CO_2+H_2S$ to understand the effect of the parameters either individually or in combination. Potentiodynamic polarization study revealed that a small amount of $CO_2$ aided in the formation of calcareous deposit of protective layer on passive film of 304 steel, while increase in $CO_2$ concentration ruptured the layer resulting in sweet corrosion. The presence of $S^{2-}$ damaged the passive and protective layer of the steel and higher levels increased the degradation rate. Electrochemical impedance studies revealed lower polarization resistance and impedance at higher concentration of $CO_2$ or $H_2S$, supporting the outcomes of polarization study. XRD analysis revealed different types of iron carbides and iron sulphides corresponding to sweet and sour corrosion as the corrosion products, respectively. SEM analysis revealed the presence of uniform, localized and sulphide cracking in sour corrosion and general corrosion with protective carbide layer amid for sweet corrosion.

• Corrosion Science and Technology
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• v.14 no.6
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• pp.288-295
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• 2015

The present work addresses crevice and galvanic corrosion processes occurring at the cylinder head gasket/cylinder head interface and cylinder head gasket/cylinder liner interface of four-stroke medium-speed diesel engines for marine applications. The contact between these systems and the marine environment can promote formation of demanding corrosion conditions, therefore influencing the lifetime of the engine components. The electrochemical behavior of various metals and alloys used as head gasket materials (both ferrous alloys and copper alloys) was investigated. The efficacy of corrosion inhibitors was determined by comparing electrochemical behavior with and without inhibitors. In particular, crevice corrosion has been investigated by electrochemical tests using an experimental set-up developed starting from the requirements of the ASTM G-192-08, with adaptation of the test to the conditions peculiar to this application. In addition to the crevice corrosion resistance, the possible problems of galvanic coupling, as well as corrosive reactivity, were evaluated using electrochemical tests, such as potentiodynamic measurements. It was possible to quantify, in several cases, the corrosion resistance of the various coupled materials, and in particular the resistance to crevice corrosion, providing a basis for the selection of materials for this specific application.

• Corrosion Science and Technology
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• v.16 no.2
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• pp.69-75
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• 2017

Zinc coating on carbon steels give the higher corrosion resistance in chloride containing environments and in carbonated concrete. However, hydrogen evolution accompanies the corrosion of zinc in the initial activity in fresh concrete, which can lead to the formation of a porous structure at the reinforcement -concrete interface, which can potentially reduce the bond-strength of the reinforcement with concrete. The present study examines the mechanism of the corrosion of hot-dip galvanized steel in detail, as in the model pore solutions and real concrete. Calcium ion plays an important role in the corrosion mechanism, as it prevents the formation of passive layers on zinc at an elevated alkalinity. The corrosion rate of galvanized steel decreases in accordance with the exposure time; however, the reason for this is not the zinc transition into passivity, but the consumption of the less corrosion-resistant phases of hot-dip galvanizing in the concrete environment. The results on the electrochemical tests have been confirmed by the bond-strength test for the reinforcement of concrete and by evaluating the porosity of the cement adjacent to the reinforcement.

• Proceedings of the Korean Environmental Health Society Conference
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• 2005.06a
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• pp.330-332
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• 2005

Ten phosphate corrosion inhibitors meet the required standards and drinking waters containing corrosion inhibitors also within 27 items of water quality standards. In addition, the T-P concentration was observed at a level of 2.342-2.909mg/L. Those results indicate that the corrosion inhibitors are not harmful and, as for drinking waters with inhibitors, they can be considered not to have any toxic influence on human body when used below the regulated level of 10mg/L.

• Journal of Korea Foundry Society
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• v.40 no.5
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• pp.129-133
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• 2020

The outcomes of solution annealing and stress corrosion cracking in cold-worked 316L austenitic stainless steel have been studied using x-ray diffraction (XRD) and the slow strain rate test (SSRT) technique. The good compatibility with a high-temperature water environment allows 316L austenitic stainless steel to be widely adopted as an internal structural material in light water reactors. However, stress corrosion cracking (SCC) has recently been highlighted in the stainless steels used in commercial pressurized water reactor (PWR) plants. In this paper, SCC and inter granular cracking (IGC) are discussed on the basis of solution annealing in a chloride environment. It was found that the martensitic contents of cold-worked 316L stainless steel decreased as the solution annealing time was increased at a high temperature. Moreover, mode of SCC was closely related to use of a chloride environment. The results here provide evidence of the vital role of a chloride environment during the SCC of cold-worked 316L.

• Journal of the Korean Recycled Construction Resources Institute
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• v.2 no.4
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• pp.307-313
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• 2014

Recent interest in the increased structural performance and durability evaluation of this concrete structure in a salt damage environment is increasing. The most secure and reliable method of accelerated corrosion test is a method to carry out the rebar corrosion monitoring can be exposed directly to the marine test site exposure. However, long-term exposure testinghas the disadvantage that a long period is necessary. So, a lot of research on RC of salt damage environment have beenpromoted as alternatives to replace this. However, accelerated corrosion test, in the short term only is appropriate and is but an accelerated test method to evaluate the critical chlorine concentration, there is a difficult problem that you still get the answer. It is one of the correlation problems accelerated test correspond to a certain period of exposure environment. Therefore, in this study, to clarify the differences rebar corrosion beginning, through the actual corrosion accelerated test in corrosion time and laboratory test chamber of the structure of the marine environment results in both environments, it is an object of correlation coefficient derived.

• Corrosion Science and Technology
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• v.8 no.6
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• pp.243-250
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• 2009

When a steel sheet pipe applied to marine environment, an anti-corrosive coating should be treated to obtain long-term life-time for steels, especially, splash zone. Although anti-corrosive property of coatings is required to be tested in real marine environment, it is difficult because of long test time such as 20 years or more time. Therefore, we used cyclic corrosion tester in a laboratory, which has similar conditions with salt-dry-wet process such as real marine environment. Anti-corrosive properties of the coatings and two steels were tested their anti-corrosive properties under cyclic corrosion test conditions(KS D ISO 14993) and the results were compared with estimate life-time in real marine environment. According to cyclic corrosion test, accelerated corrosive factor of each anti-corrosive coating was investigated accelerated corrosive factor from impedance with EIS method. Accelerated corrosive factor of type SS400 carbon steel and A690 was also investigated their accelerated corrosive factor from the regression curves of weigh loss results. One of the anti-corrosive coatings showed about 50 years life-time compared with standard sample life-time. Carbon steel SS400 showed from 0.1 mm/yr to 0.06 mm/yr as its corrosion rate.

• Corrosion Science and Technology
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• v.4 no.5
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• pp.178-190
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• 2005

In order to develop a new corrosion sensor for detecting and monitoring the external and internal corrosion damage of buried pipeline, the electrochemical property of sensors and the correlation of its output to corrosion rate of steel pipe, were evaluated by electrochemical methods in two soils of varying resistivity (5,000 ohm-cm, 10,000 ohm-cm) and synthetic tap water environments. In this paper, two types of galvanic probes were manufactured: copper-pipeline steel (Cu-CS) and stainless steel-pipeline steel (SS-CS). The corrosion behavior in synthetic groundwater and synthetic tap water for the different electrodes was investigated by potentiodynamic test. The comparison of the sensor output and corrosion rates revealed that a linear relationship was found between the probe current and the corrosion rates. In the soil resistivity of $5,000{\Omega}-cm$ and tap water environments, only the Cu-CS probe had a good linear quantitative relationship between the sensor output current and the corrosion rate of pipeline steel. In the case of $10,000{\Omega}-cm$, although the SS-CS probe showed a better linear correlation than that of Cu-CS probe, the Cu-CS probe is more suitable than SS-CS probe due to the high current output.

• Environmental Engineering Research
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• v.17 no.1
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• pp.17-25
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• 2012

Concern about green water problem has surfaced as a serious issue in Korea. In order to solve this problem, it is necessary to research inhibition of green water and corrosion control of copper pipe in water service. This paper discovered that moderate corrosion inhibitors can solve the green water problem and copper corrosion in water service by adding the optimal concentration of corrosion inhibitors based on regulation. Firstly, in the case of phosphate based corrosion inhibitors, as dosage of the corrosion inhibitor increases from 1 mg/L to 5 mg/L, the relative effect of corrosion inhibitor declines rapidly. Secondly, except for 1 mg/L dosage of silicate based inhibitor, relative effects of the inhibitor displays a positive number depending on inhibitor concentration. The most significant result is that the amount of copper release shows a downward trend, whereas the phosphate based inhibitor accelerates copper ion release as the inhibitor dosage increases. Thirdly, as the dosage of mixed inhibitors increases to 10 mg/L, the copper release change shows a similar trend of phosphate based inhibitor. Lastly, according to the Langelier saturation index (LI), silicate based inhibitors have the most non corrosive value. Larson ratio (LR) indicates that phosphate based inhibitors are the least corrosive. Korea water index (KWI) represents that silicate based inhibitors are most effective in controlling copper pipe corrosion.

• Journal of Fisheries and Marine Sciences Education
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• v.11 no.2
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• pp.139-149
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• 1999

Thermal sprayed Ni-Cr alloy coating on the carbon steel was carried out erosion-corrosion test and electrochemical corrosion test in the marine environment. The erosion-corrosion behavior and electrochemical corrosion characteristics of substrate(SS400) and thermal sprayed Ni-Cr coating was investigated. The erosion-corrosion control efficiency of Ni-Cr coating to substrate was also estimated quantitatively. The main results obtained are as follows : 1) The weight loss rate of Ni-Cr coating layer by the erosion-corrosion compared with substrate was smaller. With the lapse of time, the weight loss rate of substrate was linearly increased in $25{\Omega}{\cdot}cm$ solution, but that of Ni-Cr coating became stable. 2) The corrosion potential of substrate became less noble than that of Ni-Cr coating layer, and the corrosion current density of Ni-Cr coating became lower than that of substrate. 3) The control efficiency of erosion-corrosion of Ni-Cr coating compared to substrate became more dull than that of corrosion in $25{\Omega}{\cdot}cm$ and $5000{\Omega}{\cdot}cm$ solution.