On the Pipe, Five-by-Five: Cathodic Protection on Pipelines

Pipes used to transport liquids are often prone to rusting and corrosion. Experts identify corrosion as one of the top reasons for failing pipelines, and therefore, it is essential that certain safety measures protect these infrastructures.

One such technique is cathodic protection. This process involves supplying an electrical current to the pipe from energy sources while applying an alloy to the pipe surface, to convert the anodic sites on the pipe into cathodic ones. Cathodic protection systems are perfect for pipelines, even those than run under the ground.

AC mitigation authority mearsintegrity.com explains why cathodic protection is the method of choice for protecting exposed metal structures from corrosion.

Why Cathodic Protection is Effective

Many regard cathodic protection as an effective way of controlling the corrosion of the pipes. In addition, cathodic protection systems:

• Are easy to install, including the steady supply of direct current, even those underground;
• Are easy to use and monitor, even adjust the current;
• Can combine with other anti-corrosion methods like pipe coating to prolong the pipeline lifespan;
• Can provide localized and overall protection.

Two Types of Cathodic Protection

There are two kinds of cathodic protection systems used to protect pipelines:

• Galvanic System

In this system, an alloy applies onto the pipes that have electrode potentials higher than that of the pipe, thus reducing the rate of corrosion. Zinc, aluminum and magnesium generally comprise the materials in this system. There are no energy sources required for the system to work.

• Impressed-Current System

In this system, the current directly comes from an external source. These systems are slightly more expensive, and require some time for installation.

While there are other anti-corrosion systems that can protect the pipes, pipeline cathodic protection is more effective in preventing the pipes from corroding when the coating on the pipe is poor. In addition, it is also more practical, especially when coupled with solar energy.