A Quick Overview of Cathodic Protection for the Marine Industry

Blog | April 14th, 2023

The corrosive nature of seawater, along with the presence of microorganisms and other agents, can cause severe damage to metal structures and equipment. The continuous interaction of these elements may lead to safety issues and expensive repair costs. As a solution, the marine industry utilises a technique called cathodic protection as it prevents the corrosion of metal structures and equipment that come into contact with seawater.

Cathodic protection works by providing a negative potential to the metal structures than that of seawater, which can then reduce the corrosion rate.

Types of Cathodic Protection

To date, there are two common types of cathodic protection used in the marine industry: sacrificial anode cathodic protection and impressed current cathodic protection.

Sacrificial anode cathodic protection involves the attachment of a more reactive metal like zinc or aluminium to the structure that needs to be protected. The corrosion will then occur on the sacrificial anode instead of the protected structure. Hence, they need to be replaced periodically to continue protecting the metal structures and equipment. This technique is often used for small vessels, offshore platforms, and other marine equipment.

Impressed current cathodic protection, alternatively, involves the application of an external current to the metal structure to be protected. The current is provided by an external power source, allowing it to flow from an anode to the metal structure. It can effectively increase the potential of the metal structure and reduce the corrosion rate. Impressed current cathodic protection is commonly utilised for large offshore structures like pipelines and oil rigs.

Some more types of cathodic protection can be utilised by the marine industry.

Advantages and Applications

One of the primary advantages of cathodic protection is it is a passive technique, which means it does not require active maintenance or monitoring. However, it requires periodic inspection and testing to ensure that it can continuously protect surfaces. These things should also be done to identify any potential issues right away.

Cathodic protection is widely used in the marine industry for a variety of applications. Some of the most common applications include:

• Offshore structures: Cathodic protection is used for offshore structures such as pipelines, oil rigs, and subsea equipment. These structures are exposed to seawater for extended periods. Hence, they can be highly susceptible to corrosion. Cathodic protection can, fortunately, extend the lifespan of these structures and reduce maintenance costs.
• Ships and vessels: This protection technique can also be used on ships and other vessels to protect the hull and other metal components from corrosion. It can help ensure the structural integrity of the vessel and reduce the risk of accidents or breakdowns.
• Ports and harbours: Likewise, cathodic protection can be maximised in ports and harbours to protect metal structures such as docks, piers, and mooring systems from corrosion.
• Water treatment facilities: Cathodic protection is used in water treatment facilities to protect metal structures like pipelines and tanks from elements that can cause corrosion. Through this technique, the safety and reliability of the water supply can be ensured.

Cathodic protection is an effective technique to prevent corrosion in the marine industry. It can also help in extending the lifespan of metal structures and equipment, reduce upkeep costs, and improve safety. Keep in mind that this technique can only be effective if it is installed and maintained correctly. Choosing the right technique is also a must so it can function correctly.

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