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Article
Publication date: 2 November 2015

Gan Cui, Zili Li, Lingyu Zhao and Xu Wei

The purpose of this investigation was to study these problems and design regional cathodic protection, using numerical simulation. Regional cathodic protection technology…

Abstract

Purpose

The purpose of this investigation was to study these problems and design regional cathodic protection, using numerical simulation. Regional cathodic protection technology is immature at home and abroad. This is reflected in the fact that in gas stations, there are many underground pipelines, which can lead to serious interference and shielding phenomena, and there are many grounding networks that can cause substantial loss of the cathodic protection current.

Design/methodology/approach

Based on the above, in this article, first of all, the mathematical model of the buried pipeline cathodic protection potential distribution was established and the control equations solved using the boundary element method. Second, the cathodic shielding effect in pipeline concentration areas, the effect of instrument equipment grounding systems on cathodic protection and the influence of DC stray current on the interference of pipeline corrosion were studied separately using BEASY software. Finally, the BEASY software was used for a regional cathodic protection design for a real gas station.

Findings

It was concluded that impressed current used in combination with sacrificial anodes for regional cathodic protection design is often the most economic and effective approach. However, the output current of the auxiliary anode is large with high energy consumption. In consequence, it may be recommended that the station pipelines should be laid on the ground, rather than under it.

Originality/value

It is considered that the results can guide regional cathodic protection design for real-life installations very well.

Details

Anti-Corrosion Methods and Materials, vol. 62 no. 6
Type: Research Article
ISSN: 0003-5599

Keywords

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Article
Publication date: 27 March 2007

Mohammad Zamanzade, Taghi Shahrabi and Ali Yazdian

This study aims to evaluate the influence of pulsed cathodic protection on calcareous deposit formation on structures submerged in the synthetic sea water.

Abstract

Purpose

This study aims to evaluate the influence of pulsed cathodic protection on calcareous deposit formation on structures submerged in the synthetic sea water.

Design/methodology/approach

Chronoamperometric and CHF methods have been used to evaluate the influence of pulsed cathodic protection on decreasing the required cathodic current for protection and also decreasing the surface coverage. The morphology of the formed deposits was evaluated using scanning electron microscopy. Chemical analyses of the formed deposits were performed using energy dispersive X‐ray spectrometer and X‐ray diffraction.

Findings

It was observed that pulse frequency influenced both the structure and the composition of the deposits. The most compact aragonite layer was obtained at high frequencies and at a high off‐time. It was clearly shown that by applying currents with less than 100 Hz frequency, the deposits formed on the sample involved CaCO3 (aragonite) and Mg(OH)2 (brucite). However, the kinetics of deposits formed when applying pulse current have been improved, compared to deposits formed by conventional cathodic protection. The reason is that large electrode overpotential favors nucleation through a decrease in the energy of nucleus formation. On the other hand, by intensive decrease of surface potential, repulsion of aggressive anions such as SO42− and Cl occurs. These anions inhibit the formation of aragonite deposits.

Research limitations/implications

In order to have a better investigation of electrodeposition processes in the shorter time, the use of more advanced techniques and analysis methods such as XPS is recommended. Furthermore, EHD techniques could be used for measurements of thickness of the layers.

Practical implications

The pulsed cathodic protection method is a relatively new method for the protection of buried and submerged structures. Recently, many researches have investigated that the influence of this technique on increasing the throwing power, decreasing interference effects on neighboring structures and increasing the uniformity of current distribution under cathodic protection.

Originality/value

Very little attention has been paid in the past to the effect of pulsed CP on deposit formation. The present paper, therefore, contributes useful understanding of the mechanism and advantages of such deposits in improving the effectiveness and lowering the operational cost of cathodic protection in use on offshore structures.

Details

Anti-Corrosion Methods and Materials, vol. 54 no. 2
Type: Research Article
ISSN: 0003-5599

Keywords

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Article
Publication date: 1 April 1977

B.S. Wyatt

Synopsis A brief introduction is given to the theory of cathodic protection. Principles and design procedures are described for both sacrificial anode and impressed…

Abstract

Synopsis A brief introduction is given to the theory of cathodic protection. Principles and design procedures are described for both sacrificial anode and impressed current cathodic protection with a comparative assessment of both systems and the anodes used in them.

Details

Anti-Corrosion Methods and Materials, vol. 24 no. 4
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 1 June 1985

B.S. Wyatt

Irrespective of the type of cathodic protection system applied to an offshore platform or pipeline the longevity and effectiveness of that system, and therefore the safety…

Abstract

Irrespective of the type of cathodic protection system applied to an offshore platform or pipeline the longevity and effectiveness of that system, and therefore the safety and continued revenue earning capacity of the platform or pipeline, can be assured only if adequate monitoring and surveying of the performance is undertaken.

Details

Anti-Corrosion Methods and Materials, vol. 32 no. 6
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 23 March 2010

G.H. Sedahmed, H.A. Farag, M.A. Hassan and I. Hassan

The purpose of this paper is to study the effect of the relative velocity between ship hull and seawater on the rate of zinc consumption and degree of cathodic protection

Abstract

Purpose

The purpose of this paper is to study the effect of the relative velocity between ship hull and seawater on the rate of zinc consumption and degree of cathodic protection during sacrificial cathodic protection of steel hulls using zinc anodes.

Design/methodology/approach

The rate of zinc consumption under different relative velocities was determined by the loss in weight technique while the degree of cathodic protection of the ship hull at different distances from the anode was determined by measuring the cathode potential of the hull cathode against a silver/silver chloride reference electrode.

Findings

Within the present range of conditions, the rate of zinc consumption (R) was found to increase with increasing the relative velocity according to equations: R=3.9×10−4 Re0.0126; for Re<3,500, and R=7.36×10−6 Re0.5; for Re>3,500, where Re is the Reynolds number. The degree of cathodic protection represented by the hull (cathode) potential at a given distance from the anode was found to decrease slightly with increasing the relative velocity.

Originality/value

The present results would make it possible for the designer of sacrificial cathodic protection systems to assess the amount of zinc required to protect the ship hull under certain operating conditions more accurately than the situation where the effect of the relative velocity was not considered.

Details

Anti-Corrosion Methods and Materials, vol. 57 no. 2
Type: Research Article
ISSN: 0003-5599

Keywords

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Article
Publication date: 1 July 1954

W. Godfrey Waite

The cathodic protection of ships against corrosion has a long history, for it was first applied in 1824 by Sir Humphry Davy for the protection of the copper sheathed hulls…

Abstract

The cathodic protection of ships against corrosion has a long history, for it was first applied in 1824 by Sir Humphry Davy for the protection of the copper sheathed hulls of British warships. Here the author describes the modern art of cathodic protection which can be used at every stage of a ship's life from the fitting‐out period onwards. Besides its main use for the protection of hulls, the method is applicable to propellors, stern gear, cargo compartments, etc., and it can result in very considerable savings in repair costs. The author also discusses the cathodic protection of other marine structures such as floating docks, mooring buoys, etc.

Details

Anti-Corrosion Methods and Materials, vol. 1 no. 7
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 1 April 1969

J.A. von Fraunhofer and T.S. de Gromoboy

Cathodic protection by galvanic or impressed current techniques is probably the most favoured method of obviating the corrosion of buried and immersed metals. The…

Abstract

Cathodic protection by galvanic or impressed current techniques is probably the most favoured method of obviating the corrosion of buried and immersed metals. The theoretical principles and the economics involved in such protection are well established now and have been the subject of numerous papers, monographs and reviews. Cathodic protection is, however, still far from being an infallible method of corrosion prevention primarily because (a) the cathodic protection conditions necessarily change with the environment, (b) complete corrosion protection is rarely achieved in practice (see below), and (c) corrosion of an apparently protected structure may occur through the presence of stray currents

Details

Anti-Corrosion Methods and Materials, vol. 16 no. 4
Type: Research Article
ISSN: 0003-5599

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Article
Publication date: 21 February 2019

Ziqing Yang, Gan Cui, Zili Li and JianGuo Liu

In recent years, the demand for oil and gas pipelines has increased rapidly. Due to the restrictions of the pipeline routing, pipelines are generally laid in parallel or…

Abstract

Purpose

In recent years, the demand for oil and gas pipelines has increased rapidly. Due to the restrictions of the pipeline routing, pipelines are generally laid in parallel or in the same trench, which results in stray-current interference between the independent cathodic protection (CP) systems. The purpose of this paper is to study the interference between the long-distance parallel pipelines and to obtain the optimized operation for the CP systems.

Design/methodology/approach

In this study, first, the numerical model of parallel pipelines was established using the boundary element analysis software (BEASY). Second, the effects of horizontal distance between parallel pipelines, coating damage rate, soil conductivity and anode output current on the interference of parallel pipelines were studied. Finally, by varying the layout or the output currents of CP stations, an optimized operation scheme osf long-distance parallel pipelines was put forward.

Findings

Simulation results showed that with a decrease in soil conductivity or coating damage rate, the interference increased. Moreover, the interference decreased with an increase in horizontal distance between two parallel pipelines or a decrease in anode output current. It was found that there are three methods to reduce the interference between long-distance parallel pipelines: to reduce the output currents of CP stations, combined protection and to close part of the CP stations. Among them, to close part of CP stations was the optimized scheme because of the lowest operating and maintenance cost.

Originality/value

The optimized operation scheme proposed in this study can not only solve the interference between parallel pipelines but also provide guidance for the parallel pipelines to be built in the future. Reasonably arranging the cathodic protection stations using numerical simulation can avoid the interference in the cathodic protection systems, and reduce the construction cost.

Details

Anti-Corrosion Methods and Materials, vol. 66 no. 2
Type: Research Article
ISSN: 0003-5599

Keywords

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Article
Publication date: 2 March 2015

Zhenxing Ren, Daowu Yang, Jun Liu, Yong Ma, Zhongtang Huo and Shaochang Zheng

The purpose of the paper was to design an anti-corrosion system that combined conductive coatings with cathodic protection for a 500-kV substation ground grid, and provide…

Abstract

Purpose

The purpose of the paper was to design an anti-corrosion system that combined conductive coatings with cathodic protection for a 500-kV substation ground grid, and provide a basis for the anti-corrosion construction of the installation.

Design/methodology/approach

The study took the Shaoguan 500-kV substation grounding grid as the research object. The anti-corrosion performance of KV conductive coatings on grounding metal was researched. In parallel, the alkalinity of substation soil was evaluated according to the German DIN50929 Standard, and the combined protection system comprising conductive coatings and impressed current cathodic protection was designed.

Findings

KV conductive coatings, that have resistance to acids, alkalis and salts, can effectively slow down the corrosion rate of the grounding grid. The investigation also provided the outline design, installation, construction requirements and monitoring methods for the 500-kV substation grounding grid.

Originality/value

This report contains some guiding significance for anti-corrosion engineering of 500-kV substation grounding grids.

Details

Anti-Corrosion Methods and Materials, vol. 62 no. 2
Type: Research Article
ISSN: 0003-5599

Keywords

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Article
Publication date: 17 May 2013

Xinlu Dong, Daowu Yang, Xiaoxiao Guan, Min Du and Di Liu

Reliable grounding is an important condition for the stable operation of substations and cathodic protection is one of the electrochemical protection technologies for…

Abstract

Purpose

Reliable grounding is an important condition for the stable operation of substations and cathodic protection is one of the electrochemical protection technologies for substation grounding grids. The purpose of this paper is to consider the design proposal, installation, construction requirements and monitoring methods for Hunan 220 kV substation grounding grid.

Design/methodology/approach

This paper treated Hunan 220 kV substation grounding grid as a research object. The physical and chemical data of three soil samples were measured, German DIN50929 evaluation criteria were used to assess its corrosion and a sacrificial anode cathodic protection design was selected, based on advanced concepts.

Findings

The design proposal, installation, construction requirements and monitoring methods for the 220 kV substation grounding grid were clearly explained and recommended for implementation.

Originality/value

This paper has some guidance on design ideas and the selection method for substation sacrificial anode cathodic protection.

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