SAIT S.r.l - Cathodic Protection: Active and Passive

Cathodic Protection: Active and Passive

December 20, 2024

Cathodic protection is an essential technology for preventing corrosion of metal structures, such as pipelines, tanks and bridges, that operate in aggressive environments. This system is widely used to ensure the longevity and safety of critical infrastructure.

Cathodic protection is based on the application of an electric potential to the metal to be protected, transforming it into a cathode and thus reducing the risk of corrosion. There are two main types of cathodic protection: active and passive.

Passive Cathodic Protection

Passive cathodic protection uses sacrificial anodes, made of materials such as zinc, magnesium or aluminum, which corrode instead of the metal to be protected. This system is effective for small structures or in environments where the risk of corrosion is moderate.

Advantages:

Simple to install and maintain.
It does not require an external power source.

Limits:

The life of sacrificial anodes is limited.
Not suitable for large structures or high corrosion conditions.

Active Cathodic Protection

Active cathodic protection, on the other hand, uses an impressed current, supplied by an external energy source, to protect the metal. This system is ideal for larger structures and highly corrosive conditions.

Advantages:

Effective on large infrastructures.
Greater control and adjustability of the system.

Limits:

It requires a higher initial investment.
Requires periodic maintenance.

Applications

Cathodic protection finds application in various sectors, including:

Oil and gas industries (for pipelines and storage tanks).
Maritime sector (ships and offshore platforms).
Civil infrastructure (bridges and aqueducts).

The choice between active or passive cathodic protection depends on the specific needs of the structure, the environmental conditions and the available budget.