What is Cathodic Protection?
Cathodic Protection is….
an applied technique designed to reduce the corrosion rate of metal immersed in an electrolyte such as soil, water or concrete. On the surface of a metal, there are cathodic areas where current from the surrounding electrolyte is absorbed. In contrast, at the anodic reduction areas where corrosion occurs, current flows away from the metal and into the surrounding electrolyte. If the rate of current flowing from the metal is reduced, the rate of corrosion is therefore reduced.
In the course of the cathodic protection process, the entire metal surface is converted to a current absorbing cathode. Cathodic protection is realized when direct current, which is of equal or greater value than the current flowing from the anodic areas, is forced onto the metal. The corrosion rate at the anodic areas will then be equal to zero and metal loss is subsequently eliminated, while the existing cathodic surfaces are strengthened.
CTL and Cathodic Protection
In our extensive history in the Cathodic Protection industry we have come to specialize in a number of areas related to the industry. These include:
- Cathodic Protection Systems for Pipelines, Well Casings, Tank Bottoms, and Underground Tanks
- External Corrosion Related Failure Analysis
- Impressed Current System Installations
- Horizontal, Deep-Well, and Semi-Deep Anode beds
- Sacrificial Anode System Installations
- Magnesium Anode Beds
- Zinc Anode Beds
- Aluminum Tank and Treater Systems
- Test Station Installations
- CP System Annual Surveys
- AC/DC Electrical Interference Testing
- Rectifier Maintenance/Monitoring
History of Cathodic Protection
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However, a side effect of cathodic protection was the increase in marine growth. Usually, copper when corroding releases copper ions which have an anti-fouling effect. Since excess marine growth affected the performance of the ship, the Royal Navy decided that it was better to allow the copper to corrode and have the benefit of reduced marine growth, so cathodic protection was not used further. [Ref]
Types of Cathodic Protection
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Galvanic
Is when a piece of a more electrochemically “active” metal, is attached to the vulnerable metal surface where it is exposed to an electrolyte (i.e. soil or water exposure). Galvanic anodes are selected because they have a more “active” voltage (more negative electrode potential) than the metal of the target structure (typically steel). [Ref]
Impressed Current Systems
Designed for larger structures, or where electrolyte resistivity is higher and galvanic anodes cannot deliver enough current to provide protection – impressed current cathodic protection (ICCP) systems are used. These consist of anodes connected to a DC power source, often a transformer-rectifier connected to AC power. In the absence of an AC supply, alternative power sources may be used, such as solar panels, wind power or gas powered thermoelectric generators.
Applications for Cathodic Protection
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Common applications are: steel water or fuel pipelines and steel storage tanks such as home water heaters; steel pier piles; ship and boat hulls; offshore oil platforms and onshore oil well casings; offshore wind farm foundations and metal reinforcement bars in concrete buildings and structures. At CTL: Corrosion Technologies, our focus and expertise is mainly with oilfield related pipeline structures.
WHAT CTL CORROSION TECHNOLOGIES OFFERS
Equipment & MAterials
Cathodic Protection Installation
System Surveys & Maintenance
Cathodic Protection systems require proper routine maintenance, which is imperative to achieve maximum efficiency and operation life of the Protection System. Our goal is to provide an efficient Cathodic Protection System maintenance program that is coherent with the technical and budgetary requirements of our clients.
Head Office
Innisfail, AB T4G 1S7