Hull Corrosion and How Cathodic Protection Can Protect Marine Vessels

Blog | August 24th, 2022

Most marine vessels today can conveniently transport heavy or bulky objects from one place to another. And to ensure that their main purpose can be carried out optimally, they are normally equipped with special tools that can load and unload objects conveniently.

The functionality of marine vessels pushes their manufacturers to use materials that can make them robust. After all, these marine vessels must handle the weight of the objects being loaded into their available spaces. Their materials must likewise be resistant to heat, moisture, and others as they are expected to travel from one place to another for days.

But even with strong and resistant materials, their surfaces and components can still be damaged as they will always be immersed in water for a long time. With continuous exposure to water, they may gradually corrode until they deteriorate completely.

Misconception about Marine Corrosion

One common misconception about shipbuilding is that marine vessels can already attain their needed marine corrosion protection once their surfaces have been fully coated with paint and other materials. In reality, coatings added to marine vessels do not entirely protect their surfaces. Instead, they can be damaged by water in the long run. Even undamaged coatings can also be affected by microscopic pinholes that often promote the development of corrosion.

The rate of corrosion damage to marine vessel surfaces and parts can be affected by many factors. These factors include the overall water composition, water velocity, and oxygen concentration cells related to marine growth. Marine vessels can corrode quickly if the salt percentage in the air and water is high, especially if they boast some exposed surfaces.

Marine vessels can also corrode if the surroundings are bombarded with corrosive organisms. Outdoor elements can likewise infiltrate previously sealed areas of the marine vessels, leading to another set of marine corrosion.

The Importance of Cathodic Protection

To ensure that marine vessels can be protected from corrosion, they must undergo cathodic protection. Cathodic protection is the practice of maximising electrochemical reactions to prevent corrosion from damaging the marine vessels, especially to their external hull surfaces and internal surfaces of tanks that contain seawater like ballast tanks. This practice can be done by professionals through an anode and a power supply. It can work alongside coatings through impressed current, galvanic anode techniques, or both.

Cathodic protection can be generally done by applying direct current to the marine vessel surfaces. This current application then changes the steel-to-electrolyte potential to values wherein corrosion will not be able to infiltrate the surfaces anymore. Aside from external hull surfaces and tanks, cathodic protection can also be applied to offshore floaters, subsea equipment pieces, harbours, pipelines, and all other buried metal structures.

New standards for cathodic protection may include the placement of sacrificial anodes like aluminium and zinc, which can last for a decade or two until they require replacement. When retrofitting or replacing existing cathodic protection systems, experts recommend the use of an impressed current anode that often requires an external power source.

Cathodic Protection from Professionals

To protect your marine vessels from corrosion, you must acquire cathodic protection from us at Wildon Engineering. We offer quality products that help prevent your marine vessels from obtaining corrosion and other damaging elements from the surroundings. Contact us today!

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