scholarly journals A Study of the Pitting and Uniform Corrosion Characteristics of X65 Carbon Steel in Different H2S-CO2-Containing Environments

CORROSION ◽  
10.5006/2537 ◽  
2018 ◽  
Vol 74 (8) ◽  
pp. 886-902 ◽  
Author(s):  
Frederick Pessu ◽  
Yong Hua ◽  
Richard Barker ◽  
Anne Neville
Keyword(s):  
Carbon Steel ◽  
Corrosion Behavior ◽  
Pitting Corrosion ◽  
Critical Concentration ◽  
Small Diameter ◽  
Gas Content ◽  
Co2 Corrosion ◽  
Uniform Corrosion ◽  
Corrosion Attack ◽  
The Impact

There have been increasing concerns related to the challenges posed by hydrogen sulfide (H2S) corrosion to the integrity of oilfield pipeline steels. In environments containing variable quantities of both carbon dioxide (CO2) and H2S gas, the corrosion behavior of carbon steel can be particularly complex. There is still no universal understanding of the changes in the mechanisms, sequence of electrochemical reactions and impact on the integrity of carbon steel materials as a result of changes in H2S-CO2 gas ratio. The film formation process, film characteristics, and morphology in CO2- and H2S-containing systems are also known to be different depending upon the environmental and physical conditions and this influences the rates of both general and pitting corrosion. Questions still remain as to how the combined presence of CO2 and H2S gases at different partial pressure ratios influence the corrosion mechanisms, as well as initiation and propagation of surface pits. This paper presents an investigation into the overall (i.e., general and pitting) corrosion behavior of carbon steel in CO2-H2S-containing environments. The work explores the impact of changes in ratios of CO2 and H2S partial pressures at both 30°C and 80°C in a 3.5 wt% NaCl solution. All experiments are performed at atmospheric pressure, while H2S gas content is varied at 0 ppm (0 mol%), 100 ppm (0.01 mol%), 1,000 ppm (0.1 mol%), 10,000 ppm (1 mol%), and 100,000 ppm (10 mol%) in H2S-CO2 corrosion environments. Corrosion film properties and morphology are studied through a combination of scanning electron microscopy and x-ray diffraction. The results show that the morphology and composition of iron sulfide formed changes with H2S gas concentration because of the continuous interaction of the corrosion interface with the corrosion media even in the presence of initially formed FeS (mainly mackinawite). This often leads to the formation of a different morphology of mackinawite as well as different polymorphs of FeS. This also has the impact of either increasing or decreasing the uniform corrosion rate at low and higher concentration of H2S gas depending on the temperature. Pitting corrosion is also evaluated after 168 h to determine the impact of increasing H2S content on the extent and morphology of pitting corrosion attack. The results from the pitting corrosion investigation show that increased and severe pitting corrosion attack occurs at higher H2S concentration and temperature. The morphology of pitting corrosion attack is also linked to the changes in the H2S content with an indication of a critical concentration range at which the nature of attack changes from narrow and small diameter pits to severe localized attack. The critical concentration threshold for such transition is shown in this study to reduce with increasing temperature.

scholarly journals Atmospheric Corrosion Behavior of Carbon Steel and Galvanized Steel after Exposure in Eretan and Ciwaringin, West Java Province, Indonesia

2020 ◽  
Vol 20 (5) ◽  
pp. 1032
Author(s):  
Gadang Priyotomo ◽  
Lutviasari Nuraini ◽  
Siska Prifiharni ◽  
Ahmad Royani ◽  
Sundjono Sundjono ◽  
...  
Keyword(s):  
Carbon Steel ◽  
Corrosion Rate ◽  
Corrosion Behavior ◽  
Chloride Ion ◽  
Galvanized Steel ◽  
Uniform Corrosion ◽  
Corrosion Attack ◽  
West Java ◽  
Corrosion Rates ◽  
Weight Loss Method

The investigation of corrosion for carbon steel and galvanized steel has been conducted in the marine atmosphere of Eretan and Ciwaringin Districts, West Java Province. The exposure time of the field test was up to 200 days, and their corrosion rates are determined according to weight loss method. The objective of the work is to elucidate the corrosion behavior of those alloys which is affected by distances from coastline and environmental condition. The magnitude of corrosion rate for carbon steel was 20 times as high as that for galvanized steel in both districts The distance from coastline has significantly affected for the magnitude of corrosion rate, where that both alloys in Ciwaringin is lower than that in Eretan. The deposition of chloride ion in Eretan and Ciwaringin Districts were 4.305 mg/m2 day and 1.863 mg/m2 day, respectively, where the higher chloride ion can tend to increase the corrosion rates. Relative humidity (RH) which is over 60% has essential role for corrosion process as well as rainfall. The uniform corrosion attack was observed both alloys after exposure. The corrosion product phases of galvanized steel exhibits as zincite, hydrozincite and simonkolleite in Eretan as the typical coastline atmosphere phases but not in Ciwaringin. The formation of rust product for both metals lead the decrease of further corrosion attack due to the barrier between metal and environment. The usage of galvanized steel is remarkable to minimize corrosion attack compared to that of carbon steel in tropical coastline.

scholarly journals In-Situ Monitoring and Analysis of the Pitting Corrosion of Carbon Steel by Acoustic Emission

2019 ◽  
Vol 9 (4) ◽  
pp. 706 ◽  
Author(s):  
Junlei Tang ◽  
Junyang Li ◽  
Hu Wang ◽  
Yingying Wang ◽  
Geng Chen
Keyword(s):  
Acoustic Emission ◽  
Carbon Steel ◽  
Pitting Corrosion ◽  
Optical Microscope ◽  
Open Circuit ◽  
In Situ Monitoring ◽  
Localized Corrosion ◽  
Uniform Corrosion ◽  
Corrosion Morphology

The acoustic emission (AE) technique was applied to monitor the pitting corrosion of carbon steel in NaHCO3 + NaCl solutions. The open circuit potential (OCP) measurement and corrosion morphology in-situ capturing using an optical microscope were conducted during AE monitoring. The corrosion micromorphology was characterized with a scanning electron microscope (SEM). The propagation behavior and AE features of natural pitting on carbon steel were investigated. After completion of the signal processing, including pre-treatment, shape preserving interpolation, and denoising, for raw AE waveforms, three types of AE signals were classified in the correlation diagrams of the new waveform parameters. Finally, a 2D pattern recognition method was established to calculate the similarity of different continuous AE graphics, which is quite effective to distinguish the localized corrosion from uniform corrosion.

Mechanical Properties and CO2 Corrosion Behavior of Q125 Grade Oil Tube Steel Used in Deep Oil Well

2012 ◽  
Vol 524-527 ◽  
pp. 1471-1479 ◽  
Author(s):  
Di Tang ◽  
Li Dong Wang ◽  
Hui Bin Wu ◽  
Jin Ming Liang
Keyword(s):  
Corrosion Rate ◽  
Corrosion Behavior ◽  
Pitting Corrosion ◽  
High Strength ◽  
Strengthening Mechanism ◽  
Dislocation Motion ◽  
Tube Steel ◽  
Co2 Corrosion ◽  
Oil Well ◽  
Austenite Grain

A type of Q125 grade high-strength low carbide oil tube steel was designed and researched. The strengthening mechanism of the steel was analyzed by SEM and TEM, and the CO2 corrosion behavior of the steel was simulated by high-temperature and high-pressure autoclave. The result show: the size of original austenite grain, packet and block are about 10-15μm, 2μm and 200nm, respectively, so the strength of the steel matched toughness well. The precipitate of (Nb,Ti)(C,N) whose size is about 60nm can restrain coarsening of the original austenite grain through pitting austenite grain boundary; The precipitate of (Nb,Ti)C and nanometer sized precipitate of NbC can be an effective barrier for dislocation motion, so that has great contributions to improve the strength of the steel. The average and pitting corrosion rate increased first and then dropped down with the increasing of temperature. There is a maximum of average and pitting corrosion rate at 90°C; Simultaneously, when the temperature is 90°C, there is a biggest difference between average corrosion rate and pitting corrosion rate.

Effects of Stress on Pitting Corrosion Behavior of Low-Carbon Steel

2013 ◽  
Author(s):  
Huaixiang Cao ◽  
Hao Zhang ◽  
Xingqi Qiu
Keyword(s):  
Carbon Steel ◽  
Corrosion Behavior ◽  
Pitting Corrosion ◽  
High Stress ◽  
Low Carbon Steel ◽  
Pressure Vessels ◽  
Structural Safety ◽  
Low Carbon ◽  
Corrosion Morphology ◽  
Accelerated Corrosion

Low-carbon steel Q235B was widely used in low or middle pressure equipments, which were not only withstanding the corrosive effect of the environment or medium, but also the high stress in service processes. In this paper, acetic acid accelerated corrosion test of low-carbon steel Q235B under the action of various stress levels was conducted, and its pitting corrosion behavior was studied by corrosion morphology, pitting corrosion parameters, scanning electron microscope (SEM) and energy disperse spectroscopy (EDS). The results showed that, the degree of pitting corrosion of low carbon steel Q235B with stress was more serious than that of non-stress. And the corrosion started from grain boundary, which was corroded before grain itself, and then grains fell off or dissolved. Furthermore, it would have the tendency of deep hole corrosion with stress, which was more of a threat to the structural safety of pressure vessels.

scholarly journals USING WIRE BEAM ELECTRODE (WBE) TO EVALUATE THE CORROSION BEHAVIOR OF ND STEEL IN ACID MEDIUM

2020 ◽  
Vol 1 (2) ◽  
pp. 27-30
Author(s):  
Bo Zhao ◽  
Yuxin Yu ◽  
Jing Guo ◽  
Tianyu Zhou ◽  
Shiwen Zou ◽  
...  
Keyword(s):  
Partial Pressure ◽  
Corrosion Behavior ◽  
Ring Structure ◽  
Corrosion Products ◽  
Dew Point ◽  
Co2 Corrosion ◽  
Uniform Corrosion ◽  
Corrosion Morphology ◽  
Co2 Partial Pressure ◽  
Wire Beam Electrode

In this article, wire beam electrode (WBE) was used to evaluate the corrosion behavior of ND steel in environmental acid atmosphere with different partial pressure of CO2. Meanwhile, corrosion products and surface morphology analysis also used to support this research. The results showed that the corrosion behavior began from the edge of droplet in dew point corrosion, and gradually spread to the center of it. The spread speed would be increasing with CO2 partial pressure enhance, which was 24h in 5% CO2 and 4h in 50% CO2. Corrosion current density in the edge of droplet can form the “cathode-anode-cathode ring” structure and disappears gradually as the corrosion time was going. Corrosion morphology observation results showed three ring shapes region and different elemental composition of different corrosion products, which is correspondence with the “cathode-anode We-cathode ring” structure measured in WBE experiments. The results showed that the reaction gradually transferred to the uniform corrosion on electrode surface when the dew point corrosion reaction reaching the late stage. It comes from the dissolution, diffusion and reaction of gaseous corrosion medium of CO2 and O2.

scholarly journals PENGARUH KADAR SALINITAS AIR TERHADAP LAJU KOROSI BAJA ST 60

JTAM ROTARY ◽  
2021 ◽  
Vol 3 (2) ◽  
Author(s):  
Dwi Anggi Wibowo ◽  
Abdul Ghofur
Keyword(s):  
Corrosion Rate ◽  
Construction Material ◽  
Water Environment ◽  
Aquatic Environments ◽  
Uniform Corrosion ◽  
Land Area ◽  
Corrosion Attack ◽  
Immersion Testing ◽  
Technical Properties ◽  
The Impact

Daerah perairan dapat menimbulkan risiko serangan korosi yang lebih tinggi terutama pada lingkungan perairan yang mengandung salinitas atau salinitas, umumnya korosi yang terjadi di perairan dapat menyerang logam, salah satunya adalah baja ST 60 yang banyak digunakan sebagai bahan konstruksi dalam konstruksi bangunan. pelabuhan, jembatan, poros baling-baling, dan aplikasi lain yang terkait dengan lingkungan perairan. Dampak yang ditimbulkan adalah logam dapat mengalami serangan korosi dengan cepat akibat berinteraksi dengan lingkungan air yang mengandung salinitas sehingga logam tersebut akan mengalami kerusakan dan kehilangan sifat teknisnya. Pada penelitian pengujian perendaman dilakukan dengan 3 minggu terus menerus dan 3 minggu (dengan 2 minggu perendaman kemudian 1 minggu tidak terendam) menggunakan air laut yang berasal dari pantai takisung, pelaihari dengan salinitas 2,48% dan air payau yang berasal dari dataran tinggi banjarmasin dengan salinitas 1,25%. Hasil penelitian menunjukkan laju korosi tertinggi terjadi pada 3 minggu perendaman terus menerus dengan air laut yang memiliki salinitas 2,48% dan jenis korosi yang terbentuk adalah korosi seragam. Water areas can pose a higher risk of corrosion attack, especially in aquatic environments that contain salinity or salinity, generally corrosion that occurs in the waters can attack metals, one of which is ST 60 steel which is widely used as construction material in the construction of ports, bridges, propeller axis, and other applications related to the aquatic environment. The impact caused is that the metal can experience corrosion attacks quickly due to interacting with the water environment containing salinity so that the metal will experience damage and lose its technical properties. In the study immersion testing was carried out with 3 weeks continuously and 3 weeks (with 2 weeks immersion then 1 week not submerged) using seawater originating from takisung beach, pelaihari with salinity of 2.48% and brackish water originating from the high land area of banjarmasin with a salinity of 1.25%. The results showed the highest corrosion rate occurred at 3 weeks of continuous immersion with seawater which had a salinity of 2.48% and the type of corrosion formed was uniform corrosion.

scholarly journals CO2 Corrosion of Carbon Steel: The Synergy of Chloride Ion Concentration and Temperature on Metal Penetration

CORROSION ◽  
10.5006/3583 ◽  
2020 ◽  
Vol 76 (11) ◽  
Author(s):  
Frederick Pessu ◽  
Richard Barker ◽  
Anne Neville
Keyword(s):  
Carbon Steel ◽  
Pitting Corrosion ◽  
Synergistic Effects ◽  
Chloride Concentration ◽  
Chloride Ion ◽  
Corrosion Products ◽  
Ion Concentration ◽  
Co2 Corrosion ◽  
Passive Alloys ◽  
C 50

This paper investigates the synergy of chloride ion concentration and temperature on the general and pitting corrosion of carbon steel in CO2-saturated environments. Experiments were conducted over 168 h in different concentrations of NaCl brines (1 wt%, 3.5 wt%, and 10 wt%) and temperatures (30°C, 50°C, and 80°C) with the aim of elucidating the combined effect of changes in chloride ion concentration and temperature on overall metal degradation, taking into consideration general and pitting corrosion. This also includes a correlation with the formation and properties of FeCO3 corrosion products. Linear polarization resistance was implemented to monitor the electrochemical responses. Corrosion product characteristics and morphologies were studied through a combination of scanning electron microscopy and x-ray diffraction. Pitting corrosion evaluation was conducted through the application of 3D surface profilometry to study pit geometries such as the depth and diameter. The results show that general and pitting corrosion are strongly correlated to the synergistic effects of changing chloride ion concentration and temperature in carbon steel as a result of their combined influence on ferrite (Fe) dissolution and FeCO3 formation. This represents a paradigm shift from the already established mechanisms on chloride ion and temperature effects on passive alloys such as stainless steel. Increasing chloride ion concentration and temperature up to 10 wt% NaCl and 50°C to 80°C, respectively, is observed to increase the rate of Fe dissolution and formation of semiprotective FeCO3 corrosion products, leading to the increased manifestation and severity of pitting corrosion. The results also show that a “threshold chloride concentration” exists at 30°C, above which there is no significant increase in corrosion rate. However, such “threshold effects” were not observed at higher temperatures evaluated in the range of chloride concentration considered in this study.

scholarly journals Corrosion Behavior and Failure Mechanism of Prestressed Rock Bolts (Cables) in the Underground Coal Mine

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Qiong Wang ◽  
Fengnian Wang ◽  
Aiwu Ren ◽  
Rui Peng ◽  
Jian Li
Keyword(s):  
Failure Mechanism ◽  
Corrosion Behavior ◽  
Coal Mine ◽  
Pitting Corrosion ◽  
Service Time ◽  
Outer Diameter ◽  
Uniform Corrosion ◽  
Rock Bolts ◽  
Premature Failure ◽  
Underground Coal Mine

Premature failure of rock bolts (cables) due to stress corrosion cracking (SCC) is a phenomenon that has been reported to occur in the underground environment. In the 1990s, many failure accidents of bolts which occurred in the United Kingdom were caused by SCC [1]. In this study, the corrosion behavior and failure mechanism of rock bolt (cable) samples obtained from the underground coal mine were examined and discussed. Macroscopic observation and weight loss tests were carried out for the bolts’ corrosion characteristics without failure. The results show that the bolts with short service time (1.5–2 yrs) underwent uniform corrosion. However, bolts with longer service time (3–8 yrs) experienced different pitting corrosion degrees. The corroding degree of different parts of bolt samples shows the following decreasing trend: bolt head > bolt end > free section. The absolute corrosion degree increased with the service time, while the corrosion rate was the highest in the early stage and dropped down in the later stage. At the same time, the macro- and micromethods were used to analyse the failure mechanism in the broken cable sample. Failure of one cable sample with a medium service life (6 yrs) was found to be controlled by the SCC. It was induced by long-term action of O, Cl, and S in the surrounding rock environment and resulted in pitting corrosion. The pitting corrosion reduced the outer diameter of the rock cable and its bearing capacity, leading to the final fracture.

scholarly journals In-Situ Monitoring and Analyzing Pitting Corrosion of Carbon Steel by Acoustic Emission

2018 ◽  
Author(s):  
Junlei Tang ◽  
Junyang Li ◽  
Hu Wang ◽  
Yingying Wang ◽  
Geng Chen
Keyword(s):  
Acoustic Emission ◽  
Carbon Steel ◽  
Pitting Corrosion ◽  
Optical Microscope ◽  
Open Circuit ◽  
In Situ Monitoring ◽  
Localized Corrosion ◽  
Uniform Corrosion ◽  
Corrosion Morphology

The acoustic emission (AE) technique was applied to monitor the pitting corrosion of carbon steel in NaHCO3 + NaCl solutions. The open circuit potential (OCP) measurement and the corrosion morphology in-situ capturing using optical microscope were conducted during AE monitoring. The corrosion micromorphology was characterized with scanning electron microscope (SEM). The propagation behavior and AE features of natural pitting on carbon steel were investigated. After the performing of signal processing including pre-treatment, shape preserving interpolation and denoising for raw AE waveforms, three types of AE signals can be classified in the correlation diagrams of new waveform parameters. Finally, a 2D pattern recognition method was established to calculate the similarity of different continuous AE graphics, which is quite effective to distinguish the localized corrosion from uniform corrosion.

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