Throwing Power of the Current in Anodic and Cathodic Protection

1963 ◽  
Vol 110 (6) ◽  
pp. 698 ◽  
Author(s):  
W. A. Mueller
Keyword(s):  
Cathodic Protection ◽  
Throwing Power

On the Mitigation of Corrosion Under Insulation (CUI) of Mild Steel Using Local Cathodic Protection

CORROSION ◽  
10.5006/3197 ◽  
2019 ◽  
Vol 75 (12) ◽  
pp. 1541-1551 ◽  
Author(s):  
Q. Cao ◽  
M. Brameld ◽  
N. Birbilis ◽  
S. Thomas
Keyword(s):  
Ionic Conductivity ◽  
Mild Steel ◽  
Cathodic Protection ◽  
Experimental Studies ◽  
Area Ratio ◽  
Physical Contact ◽  
Throwing Power ◽  
Copper Electroplating ◽  
Corrosion Under Insulation ◽  
Ionic Resistivity

A strategy based on cathodic protection (CP) could be a practically feasible means to protect steel piping from corrosion under insulation. However, experimental studies investigating CP of steel through moist insulation are scarce. Herein, CP was explored to protect insulated steel specimens using sacrificial zinc anodes. The conditions to effectively impart CP through the moist insulation have been discussed. The “throwing power” or protection achieved using sacrificial zinc anodes coupled with mild steel specimens in moist insulation was also estimated using copper electroplating. It was validated that the efficacy of CP depends upon the ionic resistivity of the moist insulation and the moisture content (by volume) must be >25% for efficient ionic conductivity through the insulation. The maximum throwing power of CP through the insulation was achieved when zinc was in direct physical contact with mild steel, with zinc to mild steel area ratio being 1:10.

scholarly journals Throwing Power of Embedded Anodes for the Galvanic Cathodic Protection of Steel in Concrete

2021 ◽  
Vol 6 (1) ◽  
pp. 17
Author(s):  
Bjorn Van Belleghem ◽  
Tim Soetens ◽  
Mathias Maes
Keyword(s):  
Relative Humidity ◽  
Cathodic Protection ◽  
Chloride Concentration ◽  
Steel Reinforcement ◽  
Throwing Power ◽  
External Reference ◽  
Corrosion Of Steel ◽  
Concrete Matrix ◽  
Driving Potential ◽  
Galvanic Anode

The chloride-induced corrosion of steel reinforcement is one of the main causes of deterioration of reinforced concrete structures. Cathodic protection (CP) of steel in concrete is a widely accepted repair technique to reduce, or completely stop, reinforcement corrosion. One possible method of cathodic protection is through the use of embedded galvanic (sacrificial) anodes, consisting of a zinc metal core surrounded by a precast alkali-activated cementitious mortar. The design of a CP system based on embedded galvanic anodes is based on the required amount of zinc material and the throwing power of the anode (i.e., radius around the anode in which the steel achieves sufficient protection). In this research, the protection of steel reinforcement in concrete surrounding an embedded galvanic anode was evaluated through depolarisation measurements with internal and external reference electrodes. Based on these measurements, the throwing power of the galvanic anode was determined, taking into account the 100 mV depolarisation criterium (cf. EN ISO 12696:2016). Additionally, the influence of the degree of chloride contamination of the concrete and relative humidity and temperature of the environment on the throwing power was evaluated. The results show a strong influence of chloride contamination on the throwing power of the galvanic anodes, in the sense that a higher chloride concentration in the concrete matrix leads to a reduction in the throwing power. This reduction can be related to the more negative potential of corroding steel reinforcement compared to passive steel, thus leading to a lower driving potential for the galvanic reaction. Especially when the chloride concentration is higher than 1 m% vs. cement mass, the throwing power is greatly reduced. Additionally, it was found that a higher relative humidity (RH) of the environment (and consequently, a higher RH of the concrete) resulted in a higher throwing power.

The Experimental Measurement on the Throwing Power of Sacrificial Anode Cathodic Protection for Concrete Piles in Natural Sea Water

2015 ◽  
Vol 1125 ◽  
pp. 350-354 ◽  
Author(s):  
Jin A Jeong ◽  
Chung Kuk Jin
Keyword(s):  
Reinforced Concrete ◽  
Cathodic Protection ◽  
Sea Water ◽  
Protection System ◽  
High Resistivity ◽  
Sacrificial Anode ◽  
Throwing Power ◽  
Water Line ◽  
Concrete Piles ◽  
Cathodic Protection System

This paper represents the experimental studies on the throwing power of sacrificial anode cathodic protection system applied to reinforced concrete piles in salt water condition by means of zinc anodes. Many previous studies show the effectiveness of sacrificial anode cathodic protection system, however, the major problem of sacrificial anode cathodic protection system is limited a distance to the point reaching protection current from the anode in high resistivity environments such as concrete, etc. In case of concrete pile in sea water condition, it should be combined submerged zone, tidal zone, splash zone, and atmospheric zone. In this study, the cathodic protection current by zinc sacrificial anodes was limited to scores of centimeters above the water line with tidal, depending on the concrete resistivity. Experimental tests were carried out on pile type reinforced concrete specimens with the change of water level. The test factors were corrosion and protection potential, current, and 4 hour depolarization potential. As a result of tests, cathodic protection current by zinc sacrificial anode was influenced up to about 10cm above the water line, and high resistivity areas such as atmospheric zone could not be protected with this system.

Anwendung des kathodischen Korrosionsschutzes für den Bewehrungsstahl in Beton / Applications of Cathodic Protection to Steel in Concrete

2000 ◽  
Vol 6 (6) ◽  
pp. 655-668
Author(s):  
L. Bertolini ◽  
F. Bolzoni ◽  
L. Lazzari ◽  
P. Pedeferri
Keyword(s):  
Corrosion Resistance ◽  
Reinforced Concrete ◽  
Hydrogen Embrittlement ◽  
Corrosion Rate ◽  
Cathodic Protection ◽  
Operating Conditions ◽  
Throwing Power ◽  
Control Corrosion ◽  
Chloride Contaminated ◽  
Prestressed Structures

Abstract The paper deals with the application of cathodic protection of steel in atmospherically exposed reinforced concrete. The use of this technique to control corrosion rate in chloride contaminated constructions and to improve the corrosion resistance of reinforcement in new structures expected to become contaminated is discussed. The more recent applications of cathodic protection on carbonated concrete are also considered. For each type of application, principles and operating conditions (potential and current applied, throwing power, risk of hydrogen embrittlement in the case of prestressed structures) are discussed. Examples of cathodic protection and prevention in bridges, and buildings are reported.

The study of the electrochemical properties of zinc-rich coating on the base of water sodium silicate

2019 ◽  
Vol 24 (4) ◽  
pp. 51-58
Author(s):  
Le Hong Quan ◽  
Nguyen Van Chi ◽  
Mai Van Minh ◽  
Nong Quoc Quang ◽  
Dong Van Kien
Keyword(s):  
Carbon Steel ◽  
Electrochemical Properties ◽  
Sodium Silicate ◽  
Cathodic Protection ◽  
Electrochemical Impedance ◽  
Steel Substrate ◽  
Electrical Contact ◽  
Electrochemical Impedance Spectra ◽  
Pure Zinc ◽  
Electric Circuits

The study examines the electrochemical properties of a coating based on water sodium silicate and pure zinc dust (ZSC, working title - TTL-VN) using the Electrochemical Impedance Spectra (EIS) with AutoLAB PGSTAT204N. The system consists of three electrodes: Ag/AgCl (SCE) reference electrode in 3 M solution of KCl, auxiliary electrode Pt (8x8 mm) and working electrodes (carbon steel with surface treatment up to Sa 2.5) for determination of corrosion potential (Ecorr) and calculation of equivalent electric circuits used for explanation of impedance measurement results. It was shown that electrochemical method is effective for study of corrosion characteristics of ZSC on steel. We proposed an interpretation of the deterioration over time of the ability of zinc particles in paint to provide cathodic protection for carbon steel. The results show that the value of Ecorr is between -0,9 and -1,1 V / SCE for ten days of diving. This means that there is an electrical contact between the zinc particles, which provides good cathodic protection for the steel substrate and most of the zinc particles were involved in the osmosis process. The good characteristics of the TTL-VN coating during immersion in a 3,5% NaCl solution can also be explained by the preservation of corrosive zinc products in the coating, which allows the creation of random barrier properties.

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