Effectiveness of Cathodic Protection under AC Interference and Determination of the Optimum Protection Potential

ICPTT 2011 ◽  
2011 ◽  
Author(s):  
Yan Yang ◽  
Zili Li ◽  
Qingmiao Ding
Keyword(s):  
Cathodic Protection ◽  
Protection Potential ◽  
Ac Interference

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 STABILITY ASSESSMENT OF PIPELINE CATHODIC PROTECTION POTENTIALS UNDER THE INFLUENCE OF AC INTERFERENCE

2018 ◽  
Vol 66 ◽  
pp. 19-28
Author(s):  
Thabane Hendry Shabangu ◽  
Purva Shrivastava ◽  
Bolanle Tolulope Abe ◽  
Peter A. Olubambi
Keyword(s):  
Cathodic Protection ◽  
Stability Assessment ◽  
Ac Interference

scholarly journals Numerical Model for Simulation of the Cathodic Protection System with Dynamic Nonlinear Polarization Characteristics

2020 ◽  
Vol 19 ◽  
Keyword(s):  
Numerical Model ◽  
Current Density ◽  
Cathodic Protection ◽  
Electric Potential ◽  
Protection System ◽  
Nonlinear Polarization ◽  
Electrode Surfaces ◽  
Polarization Characteristics ◽  
Cathodic Protection System

Cathodic protection is defined as a method for slowing down or complete elimination of corrosion processes on underground or underwater, insulated or uninsulated metal structures. Protection by cathodic protection system is achieved by polarizing protected object to more negative value, with respect to its equilibrium potential. Design of the cathodic protection system implies determination of the electric potential and current density on the electrode surfaces after installation of the cathodic protection system. Most efficient way for determination of the electric potential and current density in the cathodic protection system is by applying numerical techniques. When modeling cathodic protection systems by numerical techniques, electrochemical reactions that occur on electrode surfaces are taken into account by polarization characteristics. Because of nature of the electrochemical reactions, polarization characteristics are nonlinear and under certain conditions can be time – varying (dynamic nonlinear polarization characteristics). This paper deals with numerical modeling of the cathodic protection system with dynamic nonlinear polarization characteristics. Numerical model presented in this paper is divided in the two parts. First part, which is based on the direct boundary element method, is used for the calculation of the distribution of electric potential and current density on the electrode surfaces in the spatial domain. Second part of the model is based on the finite difference time domain method and is used for the calculation of the electric potential and current density change over time. The use of presented numerical model is demonstrated on two simple geometrically examples.

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