What is cathodic protection?
Cathodic protection (CP) is a technique used to inhibit the corrosion of metal (such as steel and steel reinforcement) on structures, bridges, jetties, railroads, ships, and within pipelines and liquid storage tanks. The process of corrosion almost always causes aesthetical damage, but in dyer cases, it can lead to structural failure and serious health problems for individuals who come into contact with the affected metals. Cathodic protection is simple yet effective, even in extremely corrosive environments.
Types of cathodic protection systems
Construction workers, including our own, use two basic methods of cathodic protection – galvanic (for standard anti-corrosion) and impressed current (for severe cases of corrosion):
- Galvanic cathodic protection uses an electronic metal anode attached to the affected area to generate superficial electrochemical anodes called `sacrificial anodes`. The sacrificial anodes are targeted by corrosion rather than the original metal, and thus, acting as a protective barrier against galvanic corrosion. The anodes are made from aluminium, magnesium, or zinc, and only last a limited time (approx. 15-20 years) before they need to be replaced.
- Impressed current cathodic protection is normally used when the galvanic method is not enough to battle extreme corrosion. This type of cathodic protection involves linking the anode to a power supply to create a much stronger, consistent current to provide around-the-clock protection. The anodes are made from cast iron, steel, graphite, or mixed scrap metal and their sturdiness means they last longer than their galvanic siblings (25-50 years depending on the design-build).
Generally, galvanic protection is used as standard protection and impressed current is used for a stronger and longer level of protection. There is a third method – coatings and sprays.
Please speak to a specialist trained in cathodic protection for more information.
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