Cathodic protection by zinc sacrificial anodes: Impact on marine sediment metallic contamination

Abstract An account is given of work done by the Navy Bureau of Ships with cathodic protection of active and reserve ships. Because it is difficult to dissociate costs for maintenance and corrosion protection it is impossible to say whether or not the cost of cathodic protection of active ships is merited. Because corrosion damage to hulls seldom is considered except when perforations occur, or in destroyers and sub-marines where plates are thinner and original dimensions more critical, there is some belief that cathodic protection for all ships cannot be justified on a cost basis. With inactive ships, however, the reverse is true. Indefinite extension of drydocking times, the interval contingent on the exhaustion of anti-fouling paints, is anticipated. Initial cost of cathodic protection of active destroyers, submarines, and five types of reserve ships is tabulated. Details of cathodic protection systems for reserve ships are given. Criteria of protection differ somewhat from the accepted standards. In polluted waters inactive ships may require a potential in excess of 1 volt, while in other high resistivity waters 0.85 to 0.95 volts are sufficient. Some data are given on the cathodic protection of active ships. Merits of sacrificial anodes versus impressed current are listed. Extensive further activity in cathodically protecting active ships is contingent on the outcome of trials now under way.

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Characterization of Al-Zn-Sn as Sacrificial Anodes to Protect Underground Oil Pipelines in Al-Hilla Regional

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.628.135 ◽

2012 ◽

Vol 628 ◽

pp. 135-143

Author(s):

Kadhim F. Al-Sultani ◽

Jenan Nasser Nabat

Keyword(s):

Aluminum Alloys ◽

Cathodic Protection ◽

Steel Sample ◽

Sacrificial Anode ◽

Sacrificial Anodes ◽

Oil Pipelines ◽

Protection Potential ◽

Pass Through ◽

Selection Of

Sacrificial anode cathodic protection is one of the most widely used methods in protecting buried oil pipe lines against the corrosion damages. In the present work, a series of Aluminum alloys have been prepared as sacrificial anodes candidates to be used in the protection of the oil pipelines that pass through the Al-Hilla region. These prepared alloys were microstructurally and electrochemically characterized to evaluate their performance as Al-sacrificial anodes for cathodic protection of oil pipes The relationships between the protection potential with time, sacrificial anode life, discharge currents, and capacity of sacrificial anodes were found, taking into consideration the distance between sacrificial anode and protected steel sample. According to the results obtained, the best selection of sacrificial anodes was (Al-4% Zn-0.5% Sn) alloy at 30cm in Al-Hilla region.

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Effects of Titanium Combined with Aluminium on the Electrochemical Properties and Efficiency of Mg-Mn Anodes

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.264-265.783 ◽

2011 ◽

Vol 264-265 ◽

pp. 783-788

Author(s):

E. Fadaei ◽

M. Emamy ◽

C. Dehghanian ◽

M. Karshenas

Keyword(s):

Electrochemical Properties ◽

Cathodic Protection ◽

Electrochemical Behavior ◽

Titanium Content ◽

Short Term ◽

Electrochemical Tests ◽

Sacrificial Anodes ◽

Protection Systems ◽

Work Samples ◽

Magnesium Anode

Magnesium sacrificial anodes are widely used in cathodic protection systems. In the present work, samples of Mg-0.7% Mn- x% Al- y% Ti (x,y = 0-0.6) alloys were electrochemically characterized to evaluate their performance as magnesium sacrificial anodes. The experiments focused on the influence of aluminium and titanium contents on the electrochemical behavior and efficiency of anodes. Aluminium and titanium was used in different concentrations ranging from 0.15 to 0.60 at.%. Short-term electrochemical tests, ASTM G97-89, as well as polarization curves were performed to obtain electrochemical behavior and efficiency and to reveal any tendencies to be passive. It is shown that by increasing titanium content an improvement of electrochemical properties of magnesium anode such as current capacity and electrochemical efficiency can be obtained.

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Effects of Tin on Aluminum – Zinc Alloy as Sacrificial Anode to Protect Underground Oil Pipeline in Al-Mahawil Regional

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.468-471.1585 ◽

2012 ◽

Vol 468-471 ◽

pp. 1585-1594 ◽

Cited By ~ 1

Author(s):

Kadhim F. Al-Sultani ◽

Jnan Nasser Nabat

Keyword(s):

Cathodic Protection ◽

Steel Sample ◽

Zinc Alloy ◽

Sacrificial Anode ◽

Oil Pipeline ◽

Sacrificial Anodes ◽

Oil Pipelines ◽

Protection Potential ◽

Pass Through ◽

Selection Of

Abstract Sacrificial anode cathodic protection is one of the most widely used methods in protecting buried oil pipe lines against the corrosion damages. In the present work, a series of Aluminum alloys have been prepared as sacrificial anodes candidates to be used in the protection of the oil pipelines that pass through the Al-Mahawil region. These prepared alloys were microstructurally and electrochemically characterized to evaluate their performance as Al-sacrificial anodes for cathodic protection of oil pipes The relationships between the protection potential with time, sacrificial anode life, discharge currents, and capacity of sacrificial anodes were found, taking into consideration the distance between sacrificial anode and protected steel sample. According to the results obtained, the best selection of sacrificial anodes was Al-4% Zn-0.4% Sn) alloy at 30cm in Al-Mahawil region.

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Study on the Electrochemical Behavior of Al-6Zn-0.02In-1Mg-0.03Ti Sacrificial Anodes for Long-Term Corrosion Protection in the Ocean

CORROSION ◽

10.5006/3404 ◽

2020 ◽

Vol 76 (4) ◽

pp. 366-372 ◽

Cited By ~ 1

Author(s):

Mingkun Yang ◽

Yan Liu ◽

Zeyao Shi ◽

Xiaodan Lv ◽

Bin Liu ◽

...

Keyword(s):

Mass Loss ◽

Corrosion Product ◽

Cathodic Protection ◽

Electrochemical Behavior ◽

Open Circuit Potential ◽

Open Circuit ◽

Output Current ◽

Alloy Anode ◽

Sacrificial Anodes

After 10 y of service in the ocean, the long-term performance of Al-6Zn-0.02In-1Mg-0.03Ti aluminum alloy sacrificial anodes for steel piles was characterized by mass loss in addition to optical and electron microscopy analysis. The electrochemical behavior was conducted by open-circuit potential with potentiodynamic and potentiostatic polarizations. The results showed that cathodic protection potential was in the range of −0.960 VCSE to −1.103 VCSE. The corrosion type and consumption rate of the alloy anode were related to the output current. In harsh corrosion environments, the alloy anode showed uniform corrosion and lost more mass due to voltage output, therefore more current is needed to fulfill cathodic protection. Otherwise, localized corrosion and less mass loss were observed. The alloy anodes were covered by marine creatures and corrosion product. The corrosion product contained amorphous Al(OH)3 and MgAl2(CO3)(OH)·xH2O which became more crystalline from outside to inside of the alloy anode. A translucent corrosion product was found on the alloy anode surface which contained amorphous Al(OH)3·xH2O with S, along with AlxCly(OH)z·mH2O. The electrochemical performance of the alloy anode was strongly reduced by the coverage of corrosion product. Consequently, the open-circuit potential of the alloy anode increased and the output current decreased. The effect of corrosion product thicknesses on the anodic activation is not remarkable.

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Cathodic Protection with Sacrificial Anodes

Corrosion Reviews ◽

10.1515/corrrev.2006.24.3-4.231 ◽

2006 ◽

Vol 24 (3-4) ◽

Cited By ~ 12

Author(s):

S. Szabo ◽

I. Bakos

Keyword(s):

Cathodic Protection ◽

Sacrificial Anodes

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Effect of Cathodic Protection Systems with Zn-Mesh Sacrificial Anodes on Reinforced Concrete Structures in an Accelerated Marine Environment

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.800.365 ◽

2013 ◽

Vol 800 ◽

pp. 365-374 ◽

Cited By ~ 1

Author(s):

Jin A Jeong ◽

Chung Kuk Jin

Keyword(s):

Reinforced Concrete ◽

Current Density ◽

Cathodic Protection ◽

Concrete Structures ◽

Chloride Concentration ◽

Reinforced Concrete Structures ◽

Marine Environments ◽

Concrete Piles ◽

Sacrificial Anodes ◽

Protection Potential

In the present study, corrosion and cathodic protection (CP) characteristics of concrete piles exposed to marine environments such as marine bridge columns or pier structures were evaluated under simulated conditions. The accelerated environmental tests were carried out at an elevated temperature (40°C) and a high chloride concentration (15%). The protection potential of CP systems with Zn-mesh sacrificial anodes applied to piles was inversely proportional to the water content in the concrete. When the CP system was applied after corrosion initiation and propagation (CProt), the protection current density was higher than when the CP system was applied at the beginning of structural construction (CPrev). However, the four-hour depolarization potential was higher in the latter case than in the former. In addition, it was found that even though the current density of the CPrev system was relatively lower than that of the CProt system, the CPrev system was also able to prevent corrosion. Consequently, both CProt and CPrev systems are very effective at preserving reinforced concrete structures, especially in marine environments.

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Development of carbon anode for cathodic protection of mild steel in chloride environment

Anti-Corrosion Methods and Materials ◽

10.1108/acmm-07-2017-1817 ◽

2018 ◽

Vol 65 (2) ◽

pp. 158-165 ◽

Cited By ~ 2

Author(s):

Ayomide Osundare ◽

Daniel Toyin Oloruntoba ◽

Patricia Popoola

Keyword(s):

Cast Iron ◽

Corrosion Rate ◽

Mild Steel ◽

Marine Environment ◽

Cathodic Protection ◽

Corrosion Behaviour ◽

Weight Percent ◽

Content Type ◽

Sacrificial Anodes ◽

Grey Cast

Purpose The purpose of this paper is to develop technically efficient and economically effective sacrificial anodes that can be used for cathodic protection (CP) of pipelines in marine environment and fill the knowledge gap in the use of carbon anodes for CP. Design/methodology/approach A sacrificial anode was produced via sand casting by adding varying weight-percent of coal and ferrosilicon to a constant weight-percent of grey cast iron. The hardness of the produced anodes was evaluated using a Rockwell hardness tester. The microstructure of the anodes was observed with scanning electron microscope/energy-dispersive spectroscopy (SEM/EDS). X-ray diffraction (XRD) was used to study the phases present. A potentiostat was used to assess the corrosion behaviour of the produced anodes and mild steel in 3.5 Wt.% NaCl solution. Findings The SEM results showed that some anodes had interdendritic graphite formation, while others had pronounced graphite flakes. The EDS analysis showed carbon and iron to be the prominent elements in the anode. Anodes Bc, B2 and B5 with a corrosion rate of two order of magnitudes were observed to have similar dendritic structures. Anode B4 is the most electronegative with an Ecorr of −670.274 mV Ag/AgCl and a corrosion rate of 0.052475 mmpy. The produced anodes can be used to protect mild steel in the same environment owing to their lower Ecorr values compared to that of mild steel −540.907 mV Ag/AgCl. Originality/value Alloying has been majorly used to improve the efficiency of sacrificial anodes and to alleviate its setbacks. However, development of more technically efficient and economically effective sacrificial anodes via production of composite has not been exhaustively considered. Hence, this research focuses on the development of a carbon based anode by adding natural occurring coal and ferrosilicon to grey cast iron. The corrosion behaviour of the produced anode was evaluated and compared to that of mild steel in marine environment.

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The Effect of Increasing the Amount of Indium Alloying Material on the Efficiency of Sacrificial Aluminium Anodes

Materials ◽

10.3390/ma14071755 ◽

2021 ◽

Vol 14 (7) ◽

pp. 1755

Author(s):

Krzysztof Zakowski ◽

Juliusz Orlikowski ◽

Kazimierz Darowicki ◽

Marcin Czekajlo ◽

Piotr Iglinski ◽

...

Keyword(s):

Cathodic Protection ◽

Surface Profile ◽

Zinc Content ◽

Indium Content ◽

General Corrosion ◽

Alloy Matrix ◽

Sacrificial Anodes ◽

Aluminium Anodes ◽

Lower Capacity ◽

A Current

Al-Zn-In alloys having 4.2% zinc content and various indium content in the range of 0.02–0.2% were tested with respect to the most important electrochemical properties of sacrificial anodes in a cathodic protection, i.e., the current capacity and potential of the operating anode. The distribution of In and Zn in the tested alloys was mapped by means of the EDX technique, which demonstrated that these elements dissolve well in the alloy matrix and are evenly distributed within it. The current capacity of such alloys was determined by means of the method of determining the mass loss during the dissolution by a current of known charge. The results obtained demonstrate that the current capacity of Al-Zn-In alloy decreases with the increase in the In content, which results in an increased consumption of anode material and shorter lifetime of anodes. With 0.02% In content, the capacity amounted to approx. 2500 Ah/kg, whereas the alloy with 0.2% In had as much as 30% lower capacity amounting to approx. 1750 Ah/kg. Microscopic examination for the morphology and surface profile of the samples after their exposure demonstrated that a higher indium content in the alloy results in a more uneven general corrosion pattern during the dissolution of such alloy, and the cavities (pits) appearing on the alloy surface are larger and deeper. As the indium content is increased from 0.02% to 0.05%, the Al-Zn-In alloy potential decreases by about 50 mV to −1100 mV vs. Ag/AgCl electrode, which is advantageous in terms of using this alloy as a sacrificial anode. When the indium content is further increased from 0.05% to 0.2%, the potential of the alloy is no longer changed to a more negative one. The results obtained from all these tests demonstrate that alloys containing up to 0.05% of In additive are practically applicable for cathodic protection.

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