scholarly journals AC Corrosion of Carbon Steel under Cathodic Protection Condition: Assessment, Criteria and Mechanism. A Review

Materials ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2158
Author(s):  
Andrea Brenna ◽  
Silvia Beretta ◽  
Marco Ormellese
Keyword(s):  
Carbon Steel ◽  
Cathodic Protection ◽  
Grey Literature ◽  
Reference Electrode ◽  
Steel Structures ◽  
Localized Corrosion ◽  
Corrosion Mechanism ◽  
Narrative Literature Review ◽  
Protection Potential ◽  
Ac Interference

Cathodic protection (CP), in combination with an insulating coating, is a preventative system to control corrosion of buried carbon steel pipes. The corrosion protection of coating defects is achieved by means of a cathodic polarization below the protection potential, namely −0.85 V vs. CSE (CSE, copper-copper sulfate reference electrode) for carbon steel in aerated soil. The presence of alternating current (AC) interference, induced by high-voltage power lines (HVPL) or AC-electrified railways, may represent a corrosion threat for coated carbon steel structures, although the potential protection criterion is matched. Nowadays, the protection criteria in the presence of AC, as well as AC corrosion mechanisms in CP condition, are still controversial and discussed. This paper deals with a narrative literature review, which includes selected journal articles, conference proceedings and grey literature, on the assessment, acceptable criteria and corrosion mechanism of carbon steel structures in CP condition with AC interference. The study shows that the assessment of AC corrosion likelihood should be based on the measurement of AC and DC (direct current) related parameters, namely AC voltage, AC and DC densities and potential measurements. Threshold values of the mentioned parameters are discussed. Overprotection (EIR-free < −1.2 V vs. CSE) is the most dangerous condition in the presence of AC: the combination of strong alkalization close to the coating defect due to the high CP current density and the action of AC interference provokes localized corrosion of carbon steel.

scholarly journals Corrosion of Carbon Steel in Artificial Geothermal Brine: Influence of Carbon Dioxide at 70 °C and 150 °C

Materials ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 3801 ◽  
Author(s):  
Gabriela Aristia ◽  
Le Quynh Hoa ◽  
Ralph Bäßler
Keyword(s):  
Carbon Dioxide ◽  
Carbon Steel ◽  
Temperature Effect ◽  
Electrochemical Impedance ◽  
Corrosion Products ◽  
Localized Corrosion ◽  
Corrosion Mechanism ◽  
Sem Images ◽  
Geothermal Brine ◽  
Corrosive Effect

This study focuses on the corrosion mechanism of carbon steel exposed to an artificial geothermal brine influenced by carbon dioxide (CO2) gas. The tested brine simulates a geothermal source in Sibayak, Indonesia, containing 1500 mg/L of Cl−, 20 mg/L of SO42−, and 15 mg/L of HCO3− with pH 4. To reveal the temperature effect on the corrosion behavior of carbon steel, exposure and electrochemical tests were carried out at 70 °C and 150 °C. Surface analysis of corroded specimens showed localized corrosion at both temperatures, despite the formation of corrosion products on the surface. After 7 days at 150 °C, SEM images showed the formation of an adherent, dense, and crystalline FeCO3 layer. Whereas at 70 °C, the corrosion products consisted of chukanovite (Fe2(OH)2CO3) and siderite (FeCO3), which are less dense and less protective than that at 150 °C. Control experiments under Ar-environment were used to investigate the corrosive effect of CO2. Free corrosion potential (Ecorr) and electrochemical impedance spectroscopy (EIS) confirm that at both temperatures, the corrosive effect of CO2 was more significant compared to that measured in the Ar-containing solution. In terms of temperature effect, carbon steel remained active at 70 °C, while at 150 °C, it became passive due to the FeCO3 formation. These results suggest that carbon steel is more susceptible to corrosion at the near ground surface of a geothermal well, whereas at a deeper well with a higher temperature, there is a possible risk of scaling (FeCO3 layer). A longer exposure test at 150 °C with a stagnant solution for 28 days, however, showed the unstable FeCO3 layer and therefore a deeper localized corrosion compared to that of seven-day exposed specimens.

scholarly journals Effect of CO2 Partial Pressure on the Corrosion Behavior of J55 Carbon Steel in 30% Crude Oil/Brine Mixture

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1765 ◽  
Author(s):  
Haitao Bai ◽  
Yongqing Wang ◽  
Yun Ma ◽  
Qingbo Zhang ◽  
Ningsheng Zhang
Keyword(s):  
Carbon Steel ◽  
Corrosion Rate ◽  
Crude Oil ◽  
Partial Pressure ◽  
Initial Period ◽  
Localized Corrosion ◽  
Corrosion Mechanism ◽  
Corrosion Properties ◽  
Co2 Partial Pressure ◽  
Corrosion Scale

The influence of CO2 partial pressure on the corrosion properties, including corrosion rate, morphology, chemical composition, and corrosion depth, of J55 carbon steel in 30% crude oil/brine at 65 °C was investigated. A corrosion mechanism was then proposed based on the understanding of the formation of localized corrosion. Results showed that localized corrosion occurred in 30% crude oil/brine with CO2. The corrosion rate sharply increased as the CO2 partial pressure (P co 2 ) was increased from 0 to 1.5 MPa, decreased from P co 2 = 1.5 MPa to P co 2 = 5.0 MPa, increased again at P co 2 = 5.0 MPa, and then reached a constant value after P co 2 = 9.0 MPa. The system pH initially decreased, rapidly increased, and then stabilized as CO2 partial pressure was increased. In the initial period, the surface of J55 carbon steel in the CO2/30% crude oil/brine mixtures showed intense corrosion. In conclusion, CO2 partial pressure affects the protection performance of FeCO3 by changing the formation of corrosion scale and further affecting the corrosion rate.

Influence of Oxygen Concentration and Alkalinity on the Hydrogen Gas Generation by Corrosion of Carbon Steel

2000 ◽  
Vol 663 ◽  
Author(s):  
A. Fujiwara ◽  
I. Yasutomi ◽  
K. Fukudome ◽  
T. Tateishi ◽  
K. Fujiwara
Keyword(s):  
Carbon Steel ◽  
Oxygen Concentration ◽  
Test System ◽  
Hydrogen Gas ◽  
Localized Corrosion ◽  
Generation Rate ◽  
Passive State ◽  
Corrosion Mechanism ◽  
Gas Generation ◽  
Gas Generation Rate

ABSTRACTA repository for low and intermediate level radioactive wastes will contain a great deal of carbon steel as reinforcement materials and waste containers. These steel components are expected to generate hydrogen gas due to reductive corrosion of carbon steel under repository condition. In this study, we have investigated the influence of the environmental factors such as oxygen concentration and pH in the solution on the rate of the gas generation. This rate was measured with a gas flow type test system under the controlled oxygen concentration, which simulates the redox conditions from initial to final environment in a repository. In addition, the corrosion mechanism was examined through the electrochemical tests.As a result, it has been found that pH in the solution and the oxygen concentration considerably affected the generation rate of hydrogen gas in various way. As to the influence of pH of the solution, it has been found that the gas generation rate increased with the increase of pH between 11.8 and 14. Further, as to the influence of the oxygen concentration, when the oxygen concentration in the blowing nitrogen gas was 2 ppm or more, the gas generation rate increased with the oxygen concentration. This trend was possibly caused by local decrease of pH due to localized corrosion. The gas generation rate was very low when the oxygen concentration was in the passive region. The rate was equal to 0.01 μm/y or less if the corrosion occurs with an equation: 3Fe+4H2O → Fe3O4 + 4H2 ↑ to 0.01 *m imcro;/y (hereafter we call this the equivalent corrosion rate). However the gas generation rate increased when the oxygen concentration was controlled to the extent that sufficient passive film cannot be produced and thus it shifts from passive state to active state.

Influence of soil moisture on the residual corrosion rates of buried carbon steel structures under cathodic protection

2015 ◽  
Vol 176 ◽  
pp. 1410-1419 ◽  
Author(s):  
D. Nguyen Dang ◽  
L. Lanarde ◽  
M. Jeannin ◽  
R. Sabot ◽  
Ph. Refait
Keyword(s):  
Soil Moisture ◽  
Carbon Steel ◽  
Cathodic Protection ◽  
Steel Structures ◽  
Corrosion Rates

The study of the electrochemical properties of zinc-rich coating on the base of water sodium silicate

2019 ◽  
Vol 24 (4) ◽  
pp. 51-58
Author(s):  
Le Hong Quan ◽  
Nguyen Van Chi ◽  
Mai Van Minh ◽  
Nong Quoc Quang ◽  
Dong Van Kien
Keyword(s):  
Carbon Steel ◽  
Electrochemical Properties ◽  
Sodium Silicate ◽  
Cathodic Protection ◽  
Electrochemical Impedance ◽  
Steel Substrate ◽  
Electrical Contact ◽  
Electrochemical Impedance Spectra ◽  
Pure Zinc ◽  
Electric Circuits

The study examines the electrochemical properties of a coating based on water sodium silicate and pure zinc dust (ZSC, working title - TTL-VN) using the Electrochemical Impedance Spectra (EIS) with AutoLAB PGSTAT204N. The system consists of three electrodes: Ag/AgCl (SCE) reference electrode in 3 M solution of KCl, auxiliary electrode Pt (8x8 mm) and working electrodes (carbon steel with surface treatment up to Sa 2.5) for determination of corrosion potential (Ecorr) and calculation of equivalent electric circuits used for explanation of impedance measurement results. It was shown that electrochemical method is effective for study of corrosion characteristics of ZSC on steel. We proposed an interpretation of the deterioration over time of the ability of zinc particles in paint to provide cathodic protection for carbon steel. The results show that the value of Ecorr is between -0,9 and -1,1 V / SCE for ten days of diving. This means that there is an electrical contact between the zinc particles, which provides good cathodic protection for the steel substrate and most of the zinc particles were involved in the osmosis process. The good characteristics of the TTL-VN coating during immersion in a 3,5% NaCl solution can also be explained by the preservation of corrosive zinc products in the coating, which allows the creation of random barrier properties.

Sign in / Sign up

Export Citation Format

Share Document