How Cathodic Protection Prevents Corrosion

Written by Angela

Reach out to Dreiym Engineering for any Corrosion, Electrical or Forensic Questions.

April 16, 2021

How Cathodic Protection Prevents Corrosion

It’s no secret that all metal structures are subject to rust and decay. Corrosion affects metals and can be detrimental to structures and dangerous when it causes the deterioration of pipelines, bridges, tankers, and much more. Pipeline owners know this all too well. When corrosion attacks a pipeline, it can lead to leaks that destroy the ecosystem and communities around it—dragging the business down with it.

Corrosion prevention is essential to keeping metal intact and structurally sound throughout its lifetime. There are multiple methods of prevention facilities that companies can invest in to protect their metals, but one method stands above the rest: cathodic protection. Explore this guide to how cathodic protection prevents corrosion.

Cathodic Protection: The Basics

Cathodic protection is a specific technique of corrosion control that works to keep the protected structure from decay. There are two different types of cathodic protection. The first is galvanic anode, and the second is impressed current. Each works in a unique way to achieve similar results.

Galvanic Anode Cathodic Protection

This type of cathodic protection provides a flow of protection from cathodic anodes placed in the same electrolyte as the protected metal. This flow travels from the anode into the electrolyte and discharges onto the protected metal.

In galvanic anode cathodic protection, the anode materials are zinc, aluminum, or magnesium alloys. These alloyed metals are more active than steel and most other metals. These are referred to as sacrificial anodes because they control the corrosion, so that the protected metal won’t experience it.

Impressed Current Cathodic Protection

Impressed current cathodic protection is when a DC power source is connected between the protected metal and the cathodic protection anodes. Unlike galvanic anode cathodic protection, in impressed current cathodic protection, the protection current comes from the DC power source, not the corrosion of the anode.

The anodes in this type of cathodic protection can be scrap steel, high silicon iron, or mixed metal oxides coated onto titanium. There are more alloys that can be used, but these are considered the most effective.

How Cathodic Protection Works

Each form of cathodic protection works in a slightly different manner, yet achieves the same results: a protected structure. These cathodic protection methods only function when properly set up with the protected structure. Cathodic protection should be monitored by professionals to ensure it continues to do its job.

Galvanic Anode Cathodic Protection Functionality

Galvanic anode cathodic protection is typically applied to a structure by welding the anodes to it, but this process depends on the application.

Offshore Applications

For offshore applications, or aquatic ones such as ships, tankers, and more, anodes are welded to the structure while it is being constructed.

For offshore pipelines, cathodic protection is usually administered via anodes clamped over the protective coating and connected to the pipeline through short cables or welded connection, depending on the location and type of metal.

Pipelines and Other Land-Based Applications

For land-based applications such as pipelines, they can often be protected by casting magnesium anodes onto the steel cores and connected to the pipeline through cables.

Different metal alloys should be used depending on the resistivity of the soil the pipeline is surrounded by.

Impressed Current Cathodic Protection Functionality

For impressed current cathodic protection, the method of functionality is through connecting a DC power source between the anodes and the protected metal.

Offshore Applications

For offshore and aquatic applications, anodes are often mixed metal oxide-coated titanium. They are able to be used in seawater and saline mud, and they keep relatively low consumption rates.

Land-Based Applications

For land-based applications, groups of anodes are used in ground beds. Ground beds are horizontal trenches containing multiple anodes buried in a carbonaceous backfill. This works to widen the surface area while reducing the electrical ground resistance, effectively extending the life of the anode.

What You Need To Know for Your Structure

When you run a pipeline or own a large metal structure that is vulnerable to corrosion, it’s vital to understand the important role cathodic protection plays in protection. Investing in cathodic protection done by expert engineers can prevent costly repairs and even help to avoid catastrophes later.

Leaks in pipelines can be devastating to your business and the communities and ecosystems surrounding them. Infrastructure needs to be structurally sound to function safely. Corrosion threatens the safety and structural integrity of metal.

While both of the forms of cathodic protection are functional, the type you use does matter. Most experts opt for galvanic anode cathodic protection over-impressed current because it is as effective and often found to be more reliable than impressed current. The type of corrosion prevention you use should be a collaborative decision between you and your cathodic protection experts.

Here at Dreiym Engineering, we take pride in our ability to provide professional corrosion engineering. Our cathodic protection and professional corrosion engineering consulting services keep your operations running without fear of a corrosion-caused catastrophe.If corrosion is a concern for your pipeline or other structure, consider the following services from Dreiym Engineering.

Cathodic Protection System Design

We can design a cathodic protection plan uniquely created for your structure. We handle design, construction, oversight, and tests all completed by NACE certified engineers and adhering to NACE best practices.

Pipeline and Tank Analysis and Assessment

If you’re stuck between using your current system or building a new one, our professional corrosion engineering consultants can help to determine the remaining strength and design life of your current assets while identifying areas that are high risk.

Soil Corrosivity Analysis

Understanding the surroundings of your pipeline and other structures is vital for determining the long-term health and viability of the current system. Our experts perform soil corrosivity tests to decide on the most cost-effective protection methods that are tailored to your structural environmental needs.

We are experts in how cathodic protection prevents corrosion. Contact Dreiym Engineering today for all your corrosion prevention and structural integrity needs. As a top cathodic protection contractor company, we can provide you with a quote on any of our services and ensure your structure is properly protected so its life is extended.

How Cathodic Protection Prevents Corrosion

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