Application Of Cathodic Protection Research Articles

Development of Cast AZ63 Magnesium Alloys for Cathodic Protection Applications via Alloying Additives

Development of Cast AZ63 Magnesium Alloys for Cathodic Protection Applications via Alloying Additives

Application of voltammetry as a technique to monitor cathodic protection performance of steel in simulated soil solution

Cathodic protection (CP) in combination with organic coating is applied as a secondary technique to mitigate corrosion of buried steel in an effort to prolong the lifespan of the buried steel pipeline. This study was aimed at developing and applying an adequate technique for monitoring the electrochemical behaviour of buried steel in the presence of CP. A modified voltammetry procedure was applied on carbon steel immersed in simulated soil solution for four days under open circuit potential (OCP) before applying CP for further ten days. Electrochemical impedance spectroscopy (EIS) was also applied at various time intervals to investigate the electrochemistry at the steel/solution interface. The voltammetry experiments revealed that the corrosion rate peaked at 680 µm/yr after three days of being subjected to OCP and then decreased to 411 µm/yr on day four as a result of a passive layer development on the steel surface. The corrosion rate was reduced from 411 µm/yr to 8 µm/yr as result of CP application before fluctuating between 21 and 40 µm/yr. The examination of steel surface via x-ray diffraction revealed the presence of calcareous deposit which resulted due to the application of cathodic protection.

Predicting corrosion for life estimation of ocean and coastal steel infrastructure

AbstractPhysical infrastructure in coastal and offshore locations often is constructed from mild and low alloy steels. These are prone to marine corrosion even with the application of protective coatings and cathodic protection. Particularly for high‐value assets such as energy facilities (wind farms, oil and gas production and subsea pipelines), the prediction of their safe and economic life is of much interest. Herein, a review is given of the modern development of models for the prediction of long‐term marine corrosion of steel exposed to various marine environments. These include immersion, tidal, splash and atmospheric zones and contact with sands and soils. The effects of temperature and water pollution are especially important, as is the ability of the steels or irons to form protective corrosion products. Comments are made also about other alloys such as copper‐nickels and aluminium. All show that corrosion, including pitting corrosion, develops with increased exposure time in a bimodal manner. The reasons for such behaviour are considered, together with the practical implications, important for containment structures such as pipelines, tanks and floating offshore energy platforms.

Application of impressed current cathodic protection on chain structure: An experimental study combined with COMSOL simulation

Corrosion protection of mooring chain is difficult but of great significance to guarantee the security of deep-sea operation. In consideration of the advantages and limitation of impressed current cathodic protection (ICCP), the feasibility of ICCP application on chain structure was studied through physical experiments combining with COMSOL simulation. The influence of electrical continuity on the protection potential distribution was investigated by potential measurement and numerical simulation. It was demonstrated that the conductivity was the key factor restricting the successful application of ICCP on the chain structure. With improved electrical continuity, the surface potential distribution of the chain structure under ICCP was uniform with a difference less than 12 mV, and the 90-day corrosion rate significantly reduced by 94.8% compared with that without ICCP. Furthermore, the quantitative formula of the relationship between the critical conductivity required for ICCP and the chain diameter was determined to be σc = 0.015d2 + 0.65d + 10.49. The effect of corrosion time and auxiliary anode distance on the potential distribution was also investigated. This work might provide new idea for the corrosion protection of mooring chain and provide reference for the design of mooring chain with improved possibility in corrosion protection.

Investigation of the effectiveness of armored cable in protecting the equipment of electric centrifugal pumps from corrosion

The purpose of this article is to study the effectiveness of armored cable, namely, применthe use of armored four-core cable to protect the installation of an electric centrifugal pump (ESP) from corrosion failure. Method: at the heart of the method, we consider the use of various protections such as: the impact of the inhibitory protection method and the electrochemical (cathodic) protection method, which in turn prevent the oxidative destruction of oilfield equipment parts. Result: an analysis of the application of cathodic corrosion protection using various connection modes of a four-core armored cable was carried out. Conclusion: the inhibitory method of anti-corrosion protection of equipment (ESP) has not proven itself, while the use of an armored four- core cable increased the inter-repair period by 4 times (up to 870 days). No traces of corrosion were found on the surface of the submersible motor and other underground equipment.

Effect of Conductive Coating on Silver/Silver Chloride Electrodes for Cathodic Protection Application

Measurement of pipe to soil potential in a cathodic protection system is something that must be done which aims to monitor the performance of the installed cathodic protection system. The main measuring tool in measuring pipe to soil potential is the reference electrode. The stability of the reference electrode is important as a validation of the measurement results. So far, the stability of the reference electrode is very difficult to maintain due to frequent changes caused by the environment, especially for permanent reference electrodes that are buried in the underground or installed in seawater. Permanent reference electrode sensors commonly used in seawater is the Ag/AgCl reference electrode, but in fact the Ag/AgCl reference electrode is generally unstable and must be stabilized with a KCl solution and other problems have not been produced in Indonesia. This research will be carried out by adding a conductive layer to the Ag/AgCl electrode so that its stability can be increased. The sensor manufacturing process starts from pretreatment, electrolysis and product characterization. The results of the best coating thickness and weight gain experiments showed by the highest voltage variations and time variations (4000mV and 60 minutes). The presence of conductive solid material increases corrosion resistance from 0.00391 mm/year to 0.19549 mm/year and increases the stability of the Ag/AgCl layer ± 5 mV.

Investigation of corrosion behavior, tensile and cyclic fracture mechanism of EH36 steel welded joints

This work systematically revealed the static-dynamic corrosion failure behavior of EH36 joints under air, simulated seawater and cathodic protection in seawater. The result indicated that the seawater environment affected tensile performance slightly but acted a critical role in the fatigue behavior. Specifically, the corrosion pit and cyclic stress would respectively induce high-stress concentration and corrosion current density, significantly decreasing the fatigue strength of joints. The application of cathodic protection on joints in seawater would decrease the tensile behavior, but would continuously provide electrons for the surface and crack tip to prevent corrosion damage, improving fatigue performance of EH36 joints.

Cover Picture: Materials and Corrosion. 4/2023

Cover: Second-harmonic generation (SHG) was used to monitor in-situ compositional changes to carbon steel surfaces immersed in aqueous solutions and during electrochemical experiments. For passive film formed on carbon steel samples, the response in SHG intensity showed a peak in presence of Fe3O4, while it shows a decrease in presence of Fe2O3. Upon application of cathodic protection for 30 minutes, SHG response revealed the formation and growth of a Fe3O4 film on the carbon steel surface. In this work, the results obtained with SHG were compared with in-situ active reflectance spectroscopy measurements. More detailed information can be found in: Federico Martinelli-Orlando, Eric Dénervaud, Rachel Grange, Ueli Angst, Second-harmonic generation technique for in-situ study of passive film formation on carbon steel surfaces in aqueous solutions, Materials and Corrosion 2023, 74, 508.

3D nanothorn cluster-like Zn-Bi2S3 sensitized WO3/ZnO multijunction with electron-storage characteristic and adjustable energy band for improving sustained photoinduced cathodic protection application

Solar energy-driven photoinduced cathodic protection (PICP) technology utilizes solar energy to protect marine metallic structures against severe marine corrosion. To enhance the solar energy utilization and strengthen dark-state application for realizing long-term protection, herein, a 3D nanothorn cluster-like WO3/ZnO/Zn-Bi2S3 multijunction with electron-storage characteristic and adjustable energy band was constructed. It exhibited an enhanced continuous release of photogenerated electron and sustained cathodic protection in dark conditions. Exposed to only 100 s of simulated sunlight irradiation, the WO3/ZnO/Zn-Bi2S3could store 5.27×10−2 C electrons and provide up to 5460 s of sustained CP for the coupled metal after light stops, which was 10.8 and 3.5 times higher than those of WO3/ZnO (4.89×10−3 C) and WO3/Zn-Bi2S3 (1.51×10−2 C), respectively. The WO3 nanothorn cluster-like substrate with reversible valence transformation of W6+/W5+ together with the large surface area and one-dimensional transmission path can store photogenerated electrons under illumination and release photogenerated electrons after light stops efficiently. Notably, the tri-phase heterojunction with introduction of intermediate “Carrier Springboard” ZnO between WO3 and Zn-Bi2S3 contributed to the building of well-matched energy band gradient to strengthen the directional backward transfer of photogenerated electrons and holes. The energy band of Bi2S3 sensitizer was adjusted towards negative direction by doping with zinc element to boost PICP application performance. The reversible valence transformation of Bi3+/Bi5+ could promote the consumption of photogenerated holes. These synergistically enhanced the sustained PICP performance of the WO3/ZnO/Zn-Bi2S3 photoelectrode both in dark and light conditions. This design shed light on energy-storage photoelectrodes for long-term PICP of metallic materials.

Ultrahigh current output from triboelectric nanogenerators based on UIO-66 materials for electrochemical cathodic protection

Metals are the basic and key components of most of the stuff present all around us in our living environment. The corrosion of these metals is a natural phenomenon which can be avoided through application of electrochemical cathodic protection. The triboelectric nanogenerator (TENG) is used to convert the environmental energy into electric energy. Unfortunately, the current output of TENG is always lower which limits its applications in protection of metal corrosion. In this work, we report the fabrication of efficient TENG based on UIO-66, UIO-66-NO2 and UIO-66-NH2, and use it as a power supply to construct a self-powered anticorrosion system for cathodic protection on carbon steel. The introduction of nitrate (-NO2) and amine (-NH2) groups change the Fermi level of the material, allowing the TENG to transfer more electrons during the contact. It is observed that the performance of TENG based on UIO materials is fruitful, with a maximum short-circuit current as 50.0 μA and a maximum power as 122.5 μW·cm−2. In addition, dipping experiments and electrochemical measurements showed that the TENG is capable to offer notable cathodic protection to carbon steel. The demonstrated work introduces an efficient and cost-effective strategy for scavenging the mechanical energy from environment by employing the self-powered setup to effectually protect the metals from corrosion. The assembly of auspicious self-powered cathodic protection setup based on TENG offers a great potential for versatile applications in protection of metallic corrosion activities.

3D network-like SnIn4S8/TiO2 for photoelectric electron storage and sustained cathodic protection applications in both light and dark conditions based on nanoarchitectonics

3D network-like SnIn4S8/TiO2 for photoelectric electron storage and sustained cathodic protection applications in both light and dark conditions based on nanoarchitectonics

CuInS2/TiO2 heterojunction with elevated photo-electrochemical performance for cathodic protection

Semiconductor quantum dots with high quantum yield and photovoltaic conversion efficiency have ushered in a brilliant moment for constructing internal electric field heterojunctions for photogenerated cathodic protection applications. In this paper, TiO2 nanotubes grown vertically on the surface of titanium substrates were modified via a combination of conventional electrochemical oxidation and a one-step solvothermal pathway to sensitize with CuInS2 quantum dots. Compared with pure TiO2 photoelectrodes, the modification improves sunlight absorption efficiency and provides photoelectron cathodic protection to the 304 stainless steel (304 SS). Through 9 h solvothermal reaction, the CuInS2/TiO2 coupled with protected 304 SS exhibited an excellent property when the simulated sunlight irradiation. Its mixed open circuit potential is negatively shifted to -0.99 V, at the mean time with a stable photocurrent density (118 μA cm−2). The results indicate that CuInS2 and TiO2 established a p-n heterojunction with well-matched energy level, which can effectively facilitate the carrier separation and retain the strong redox capbility of photo-induced electrons and holes.

Effective Use of Sacrificial Zinc Anode as a Suitable Repair Method for Severely Damaged RC Members Due to Chloride Attack

In many cases, the repair strategy by using sacrificial anodes for cathodic protection in real RC structures requires additional zinc anodes after several years due to the decreasing protective area. This experimental study evaluates the effectiveness of time lag application of sacrificial anode cathodic protection applied to RC beam specimens that deteriorated severely due to chloride attack. In the experiment, sacrificial anodes and cathodic protection (SACP) were applied to 41-year-old RC beam specimens exposed to natural marine environments in which the embedded steel bars were significantly corroded. The repair work was performed in three stages. Instant-off and rest potential tests of steel bars were conducted periodically to demonstrate the time-dependent depolarization value. In the first stage, a polymer-modified mortar as a patch repair material was cast to replace the concrete in the middle tensile part with small sacrificial anodes embedded in the mortar. After the protective current reaches an equilibrium state, the sacrificial anodes are disconnected from the steel bars for a year, defined as the second stage. During the one year in the second stage, the steel bar in the patch repair area remained passive, without any sign of corrosion. As for the third stage, additional sacrificial anodes were installed in the existing concrete part to protect the steel in it. From one year of observation after applying sacrificial anodes to old concrete parts, the time lag SACP application of both in patch and non-patch repair parts was clarified to be effective in stopping the corrosion of steel bar in both parts until 20–30 years based on the service life prediction. Doi: 10.28991/CEJ-2022-08-07-015 Full Text: PDF

Data analysis of the long-term residual effect of cathodic protection on reinforced concrete structures

The application of impressed current cathodic protection (CP) is a well-established technology for the corrosion protection of reinforced concrete structures situated in marine environments. While the protective benefits of cathodic protection are well known, the lasting effects following the discontinuation of CP current are not entirely understood. This paper presents research findings on the residual protective effect which is known to occur following long durations of impressed current cathodic protection. The residual effect was replicated in university laboratories using reinforced concrete test blocks and accelerated CP testing methods. The experimental results depicted a clear improvement in the electrochemical state of the reinforcing steel with a shift of 150 to 300 mV to more positive values following CP application. The research also involved analysis of monitoring data from six in-service cathodic protection systems which were operating in Australia for nearly two decades. The behaviour of the steel potential readings was analysed and the results of the combined research confirmed that the protection provided by cathodic protection systems does not actually cease when the CP current is switched off. Rather, the embedded steel undergoes a significant and sustained shift to more positive values and this phenomenon is documented and discussed in this paper.

Influence of corrosion rates on polarization and current distribution of ICCP in concrete

Corrosion rate is known to be a factor affecting the distribution of current in cathodic protection (CP) applications. This paper demonstrates the effect of different corrosion rates of embedded steel in concrete on the polarization and distribution of current during CP application. A concrete specimen was cast with separate steel bars at a fixed distance from a centralised anode. The bars are embedded in sections containing different admixed chloride concentrations to create varying corrosion rates. The specimen was conditioned to allow development of corrosion followed by application of short-term CP at a constant current of 20mA/m2. The magnitude of current flowing to each section was logged along with corresponding potential shifts. Trends were then correlated to the corrosion rates together with circuit resistance. Circuit resistance was shown to predominantly control current distribution whereas corrosion rates had a significant influence on polarization.

Variable Output Voltage Switching Rectifier for Cathodic Protection Applications With DC–DC Variable Frequency and Duty-Cycle Full-Bridge Converter

Rectifiers used in cathodic protection (CP) applications convert ac voltage to variable dc output. This article proposes a switching converter for CP, mostly to enhance the efficiency in low to medium output powers, where the duty cycle is less than 30%. This device is composed of two parts, an ac-dc converter and a dc-dc full-bridge converter. The ac-dc converter is a single-phase boost-type power factor correction converter with emphasis on high efficiency, thus resulting in an almost unity power factor and fixed dc output voltage. The dc-dc full-bridge converter operates under pulsewidth modulation with the simultaneous change of frequency and duty-cycle (SCFD) control method responding to the user output power demand. The SCFD control strategy, in this converter, increases overall efficiency of the proposed rectifier. Finally, a 1875 W prototype is implemented and tested to verify the nearly fixed high efficiency for the converter in a wide operating range of the output power.

Analysis of the Possibility of Using New Types of Protective Coatings and Abrasion-Resistant Linings under the Operating Conditions of the Spiral Classifier at KGHM Polska Miedź S.A. Ore Concentration Plant

A study was carried out to select the appropriate coatings for corrosion protection of the spiral classifier working at KGHM Polska Miedź S.A. Ore Concentration Plant. The abrasion resistance of selected protective coatings and wear-resistant linings was investigated using a DT-523 rotary abrasion tester with Taber CS-10 rubber abrasive discs. The average weight loss of the coatings after a cycle of 2000 revolutions was determined. Tests of protective coatings using the electrochemical impedance spectroscopy (EIS) technique were carried out to determine the suitability of coatings in the highly saline environment of the aqueous suspension of ground copper ore. During the measurements, changes in resistance, polarising current and capacitance were determined as a function of time for the tested coatings. The linings selected on the basis of laboratory tests were also tested under industrial conditions. Their degrees of wear were characterised. The results obtained indicated the highest abrasion resistance of materials from the polyolefin group (polyethylenes), where the average weight loss did not exceed 5 g/dm2. In the case of protective coatings, the highest durability was demonstrated by coatings with additives of ceramic aggregates, phenol-epoxy, and an elastomeric coating based on polyurea, whose average weight loss during the test cycle did not exceed 19 g/dm2. EIS measurements showed that the tested coatings were resistant to the aggressive environment of the feedstock. Tests under cathodic polarisation conditions of the samples at a potential below the protection potential showed that they were resistant to a highly saline environment and were also resistant to its alkalinisation resulting from the application of cathodic protection, which will be used to protect the classifier together with protective coatings. Tests carried out under industrial conditions using wear-resistant linings made of plastics have made it possible to analyse the mechanism and degree of wear of the various materials during the operation of the classifier. Measurements of lining wear were made in relation to baseline volumes. Polyurethane, a polymer lining based on MDI and PTMG, and those made of ultra-high-molecular-weight polyethylene with anti-stick additives showed the lowest wear rates.

CoFe prussian blue decorated BiVO4 as novel photoanode for continuous photocathodic protection of 304 stainless steel

The development of efficient photocathodic protection system requires highly active and robust light-absorbing electrodes for promoting the electron transfer from the light-absorber to the protected metal. Herein, we present an extremely active and stable CoFe prussian blue (CoFe-PB) modified BiVO4 film prepared by sequentially dipping the BiVO4 film in K3[Fe(CN)6] and CoCl2 solution, which can realize the long-term protection of 304 stainless steel under simulated solar illumination. Particularly, the photocathodic protection process can be operated in a scavenger-free environment. Our mechanism studies reveal that the CoFe-PB overlayer acts as the hole storage layer which can effective extract the photo-generated holes from the BiVO4 photoanode, and meanwhile works as an efficient catalyst that overcome the slow water oxidation barrier at the electrode/liquid interface, and thus greatly increase the electron lifetime, thereby enhancing the photocathodic protection capability. Our work provides a rather simple and effective design strategy for constructing semiconductor/electrocatalysts system for the underlying photogenerated cathodic protection application.

Application of Renewable Energy Sources Cathodic Protection and Their Economical Aspects.(Dept.E)

As cathodic protection systems are fed from 0.C. sources, a difficulty will be faced to find a suitable 0.c, source if such systems are used to protect petroleum tanks or pipe lines which lie in isolated areas far away from the existing transmission lines, Usually 3 methods could be adopted here: i) Installing a transmission link with a rectifier substation between the nearest convenient existing transmission line and the D.C. cathodic protection source. ii) Using private motor-generator sets; where the motor as a prime mover works by convenient fossil fuel. iii) Using storage battery systems, the capacity of which must be large enough to supply the required protective current during a period necessary for charging a second battery at the nearest charging station and replacing the one in use. In this case the charging battery system may he fed from rectifier substations, or private D.C. generating sots whose prime movers operate with conventional or non-conventional energy sources. This paper presents the limitations and conditions required for the conveniency of applying the non-conventional energy sources (photovoltaic) and their economical aspects in charging such batteries; together with examples of calculations clarifying the analytical steps and assumptions adopted in this study by means of which the final conclusions and results presented here were deduced. A simplified approach for the solar specific annual energy cost calculations using nomogram analysis and performance charts applied to local conditions in this respect is present od also in this paper.

Influence of metallic matrix on erosion-corrosion behaviour of high chromium cast irons under slurry impingement conditions

Chromium cast irons (CCI) comprise versatile materials that encompass a range of compositions and microstructures often chosen to promote good wear resistance. There are, however, issues that arise when the cast iron is required to operate in conditions where corrosion, as well as, wear is a factor. This scenario usually results in adapting the composition of the CCI in order to achieve higher chromium content in the metallic matrix and, thereby, to attain the corrosion resistance exhibited by high-Cr stainless steels. This paper comprises a comparison of the corrosive wear behaviour of an austenitic-based hypoeutectic cast iron and a martensitic-based, near-eutectic cast iron with the associated stainless steels, in a saline water under solid-liquid submerged jet conditions. A comprehensive experimental methodology has been adopted including evaluation of the behaviour of the materials in free erosion-corrosion conditions and with the application of cathodic protection. This approach has extended the understanding of the fundamental deterioration mechanisms in different hydrodynamic conditions and has highlighted the complexities of the mechanical/electrochemical interactions occurring during erosion-corrosion. An important feature is the influence of micro-galvanic interactions at phase boundaries. The impact of the findings has been discussed in terms of CCI alloy selection and corrosion control strategies.