Cathodic Protection

Cathodic Protection. The Trusted Solution To Arrest Corrosion of Aquatic Structures and Beyond.

Dennis Walker

March 19, 2020

Cathodic Protection. The Trusted Solution To Arrest Corrosion of Aquatic Structures and Beyond.

The definition of cathodic protection.

Corrosion of structures is everywhere. It is a natural process that weakens and breaks down metal. Corrosion occurs when four elements are present. 1. A host site from which current flows, 2. A destination site where no current flows, 3. A medium capable of conducting current like water,concrete or even soil, 4. In metal path between the host and the destination site.


Electro chemical corrosion of metals is the process by which ions of the surface of the metal are transferred to another substance, a deep polarizer and or less active metal. Depolarizers are oxygen, acids or more passive metals.

Where can you use cathodic protection?

Cathodic protection many times is used to arrest corrosion damage. Cathodic protection is the go to technology all of the world protect pipeline, water treatment plants, above and underground storage tanks, ships and bolt holes, offshore production platforms, reinforcement bars in concrete structures and piers.


Steel is highly susceptible to corrosion. Corrosion is caused when two dissimilar metals are submerged in an electrolytic substance such as water, soil or concrete. This metal conducting pathway between the two dissimilar metals allows a pathway through which free electrons move from the more active metal (anode) to the less active metal (cathodic). If free electrons from the anode do not reach active sites on the cathode before the arrival of oxygen, ions at the active sites can then recombine to produce ferrous hydroxide or rust.

The protection process.

Cathodic protection connects the base metal to a sacrificial metal that corrodes before the base metal can. Cathodic protection preserves the metal by providing a highly active metal that can act as an anode and provide free electrons. The active metal then sacrifices its ions increase the less active steel from corroding.

Arc Spray metallizing.

Metallizing is a process of spraying zinc, zinc aluminum or aluminum coating on the steel preventing rust. The zinc corrodes in place of the base metal. Metallizing is a proficient protectant yet needs to be reapplied over time. Arc Spray uses DC power to energize two conductive wires: one positive and the other negative.These energized wires are then fed through a feeder into a gun head. It is at the gun head that the wires meet and arc against each other, thus creating molten material.

Then ordinary dry compressed air is introduced to the arc zone, this atomizing the molten material into tiny droplets while also propelling then toward the prepared part. As the droplets hit the work piece or part, they flatten out and make splats. The splats interlock one on top another to createa extremely strong mechanical bond.

Impressed Current Cathodic Protection

Impressed current cathodic protection systems consist of anodes that are connected to a power source that provides a perpetual source of electrical flow. The sacrificial anode method of protection uses a metal more active than the base metal to “sacrifice” ions. These “sacrificial anodes”(usually alloys such as magnesium, aluminum, or zinc) have a stronger electrochemical potential. This method can often provide much longer protection than a sacrificial anode, as the anode is supplied by an unlimited power source.

Pile Jacketing Systems

In areas with high salinity and or road salt conditions the use of CP pile jackets are recommended. Simply placing a standard jacket arounda structure seldom stops the moister and salt intrusion from pours concrete or steel surfaces. The intrusion from around a standard jacket allows the continued corrosion and deterioration of the structure. 
Cathodic protection pile jackets use either a supplied or created electrical charge to protect the structure and stop the corrosion, reducing or eliminating further deterioration.

National Marine and diving service has licensed and experienced commercial divers to handle all of your cathodic protection projects. We take pride in repairing and restoring aquatic structures that require extra care as well as bridge infrastructure of this great nation of ours. If you have any further questions please feel free to reach us by phone. 321-412-6611.


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