The Importance of Cathodic Protection for Metal Wire
Metal is frequently used in the construction of modern infrastructures, from bridges to pipelines to electrical wires. Its durability and aesthetic appeal make it a popular choice for many industries.
However, metals are susceptible to the harmful process of corrosion. Corrosion causes refined metals to return to their natural states, which can lead to the degradation of infrastructures and even equipment failure.
One way to prevent corrosion is with cathodic protection. This strategy protects the metal from corrosion through various electrochemical processes. There are multiple forms of cathodic protection, each protecting metals in different ways.
The Corrosion Process
To comprehend how cathodic protection works, it's essential to first understand the process of corrosion.
Corrosion is a naturally occurring electrochemical instance that happens when metals are exposed to the external environment. As the metal, air and moisture react together, it causes chemical reactions. These reactions force the metal to return to its natural state as an oxide, hydroxide or sulfide.
For corrosion to occur, these elements must be present:
- Anode: In general electrochemistry, the anode is the point into which electricity moves. This movement causes the anode to lose electrons. During corrosion,this is the point where the oxidation reaction occurs and the metal deteriorates.
- Cathode: The cathode is a place on the metal that gains electrons, also known as undergoing the process of reduction. The cathode is left unaffected by corrosion.
- Electrolyte: During the corrosion process, the anode and cathode are connected through an electrical path while also residing in a conductive medium. This medium, called an electrolyte, facilitates the passage of electrons and the occurrence of corrosion.
In an electrochemical cell, corrosion occurs when electrons flow from the anode to the cathode or the two metals present. Electrons can flow because of a concept called the potential difference.
As the electrons move, a small amount of electricity generates. Electrons leave the anode and cause oxidation, which corrodes the metal. In contrast, electrons enter the anode and protect the metal from corrosion.
When the anode experiences corrosion, rust forms. The metal could degrade so much that the entire structure collapses or becomes unusable. Many industries use cathodic protection to stop or reduce the effects of corrosion on metals.
Using Cathodic Protection
Cathodic protection is based on the components of corrosion — electrolytes, cathodes and anodes. By understanding the essential principles of corrosion, you can design a pair of metals that protect one another.
In cathodic protection, you connect one metal to a more easily corroded metal. During this process, you essentially sacrifice the newly introduced metal so that you can preserve the initial metal. In other words, the new metal acts as the anode and corrodes, while the protected metal is the cathode.
Cathodic protection supplies the metal with additional electrons and removes the possibility of corrosion. Without this added protection, metals behave as anodes and rust easily. The electric current flows into the anode from the electrolyte. Once there, the current expels onto the metal and provides a protective coating. This coating regulates corrosion and keeps it from developing on the metal.
This protection is one of the strongest ways to prevent corrosion from occurring. In some instances, it removes corrosion altogether.
Bezinal® XC Coated Wire
One example of cathodic protection in action is Bezinal® XC coated wire. Numerous industries use springs for daily functions, from automotive to telecommunications. As springs are exposed to harsh elements or deformation, the Bezinal® XC coating allows the spring to resist corrosion. Due to the high protection of the coating, additional corrosion layers are unnecessary.
Bezinal® XC coated wire displays how cathodic protection can directly help industries. This coating type uses cathodic protection to shield wires from corrosion or other forms of degradation. In turn, industries can use these tools more efficiently. It lengthens the wire's lifetime, reducing time and money spent on additional coatings or replacements. The more protection your springs have, the better they protect against corrosion.
Types of Cathodic Protection
There are two major types of cathodic protection — galvanic cathodic protection (GACP) and impressed current cathodic protection (ICCP). Both involve a current flow that acts as a protector to the anode, or metal. Once the electrical wave flows out of the anode and into the electrolyte, it ejects onto the metal and controls corrosion.
There are further distinctions between the two types of cathodic protection:
Galvanic Cathodic Protection
GACP focuses on the practice of using sacrificial anodes to protect the cathode metal. This anode is more electrochemically reactive than the metal that needs protecting.
Because the anode and cathode are both together in the electrolyte, they remain electrically connected. So, when the cathode, sacrificial anode and electrolyte start experiencing corrosion, the anode begins degrading first due to its high reaction levels.
Common examples of sacrificial anodes include:
- Zinc alloys
- Aluminum alloys
- Magnesium alloys
You can design or fashion a sacrificial anode into many shapes and sizes, depending on the metal. For example, an anode for an entire steel bridge would be larger than one for a storage tank. Either way, all of these alloys are more reactive than a typical cathode like steel. Therefore, they corrode first and protect the other metal.
GACP relies on the concept of potential difference. This is the amount of voltage difference that exists between the anode and the cathode. In other words, it's the probability that electricity will be produced when the anode and cathode interact. The larger the potential difference is, the more likely the metal will be protected by the anode.
However, in some cases, there is not sufficient potential difference between the two. In these instances, engineers can use the other type of cathodic protection — impressed current cathodic protection.
Impressed Current Cathodic Protection
Professionals use ICCP when galvanic systems aren't sufficient enough to provide protection. In an impressed current system, there is an additional power source placed between the metal and anodes.
This extra source of power ensures that a large difference will occur and electrical currents will flow. Just like in galvanic protection, the cathodic protection flows from the anode, through the electrolyte and onto the metal.
ICCP systems use anodes such as:
- Scrap steel
The biggest difference between the two types is the origin of the protective current. In GACP, the electrochemical process supplies the current on its own. In ICCP, the power source provides a constant stream of electricity and facilitates corrosion.
These are some examples of power sources used in ICCP:
- Transformer rectifiers: These are highly powerful transformer tanks offering a direct voltage stream.
- Solar panels: Many engineers use solar panels as their power source, especially in remote areas or places without access to transformers.
- Batteries: You can use strong batteries to power an ICCP system.
- Gas generators: Engineers can use diesel and gas generators to provide the additional flow of power.
Usually, designers submerge the power source and connect it to the metal using underground connectors. In doing so, they reduce the risk of electrical contact for people in the area. Many lie in trench-like formations underneath the ground.
ICCP systems are extremely long-lasting, usually for around 25 years after setup. They're often used in applications that cover long structures, such as pipelines.
Applications of Cathodic Protection
Many industries use cathodic protection for a variety of purposes. Cathodic protection helps prolong the life span of equipment and makes infrastructure safer to use. It's a critical method for keeping materials secure even in harsh environments.
These are frequent applications of cathodic protection systems:
- Offshore drilling: Offshore drilling is an important process for the extraction of many resources. Most offshore drilling sites reside in salt water, which can sometimes quicken the corrosion process. Corrosion can place high stress on equipment and cause it to degrade or fail altogether. Engineers use cathodic protection to preserve equipment and keep workers safe. The process can reduce corrosion and help drilling tools remain sturdy even in the saltwater environment.
- Onshore pipelines: Many onshore pipelines are susceptible to corrosion. These underground pipelines carry gas, hazardous liquids or other essential substances. Corrosion causes the pipelines to wear down, resulting in leaks, contamination or worker injuries. Because of these risks, pipeline engineers and professionals use cathodic protection to prevent corrosion from occurring.
- Renewable energy structures: Infrastructures based on renewable energy are critical developments in the face of the climate crisis. Projects like solar power panels, wind turbines and hydroelectric stations are crucial for a more sustainable future. However, these structures exist outdoors and face the limitations of corrosion. Designers use protection techniques to reduce or avoid corrosion and keep these structures secure, such as Bezinal® XC coated wire. This zinc-aluminum coating maintains its high protection levels against corrosion even amidst highly degrading atmospheres.
- Ships: Ships are essential for transportation, carrying food, medical supplies and other goods to people worldwide. Their constant exposure to salt water and outside elements makes them prone to corrosion and degradation. Corrosion can force higher maintenance costs or cause a ship's engine to fail prematurely. Cathodic protection deteriorates the sacrificial anode, instead of the crucial outer layers of the vessel.
- Concrete structures: From buildings to bridges to sculptures, concrete is found in all kinds of construction. Concrete corrosion can be caused by exposure to salt water, industrial waste or sulfates. Other bacteria also cause rapid deterioration in concrete structures. Many engineers use cathodic protection and other preventative strategies to halt the degradation.
- Transmission lines: Transmission lines carry electric power from one point to another in an electric power system. They also use cathodic protection to ensure large voltages of power get transported safely. The cathodic protection keeps the lines from corroding, enabling them to transfer electric power without any delays.
- Guy, static and messenger wires: These wire types provide additional support to standing structures. Static wires protect against lightning, while messenger and guy wires add stability to structures like power lines. Messenger wires are essential for telecommunications and transmitting data. These wires often use cathodic protection to maximize their efforts. Normally made of steel, cathodic protection helps the wires perform to their full extent even in harsh conditions.
No matter the industry, cathodic protection keeps structures safe from deterioration. Protect your workers and maintain infrastructure security when you use cathodic-protective materials. Many tools, such as wires, have shielding qualities that induce cathodic protection.
Common Wire Types
Bekaert is the leading provider of steel wires in North America. We offer many high-quality wires and wire coating solutions that utilize cathodic protection, including:
- Bezinal® XC coated wire: You can use this wire in a variety of industries, notably for alternative energy applications. Its zinc aluminum coating uses cathodic protection to protect the wire from corrosion. In turn, the wire works more efficiently and can withstand harsh temperatures and deformation.
- Anchorage rope wire: Bekaert Anchorage rope wire is perfect for offshore drilling uses. The wires help build durable ropes designed for deep-sea applications. It can endure intense water pressures and provide strength for anchors. The rope wire uses cathodic protection strategies to prevent corrosion, making it ideal for the harsh environment.
- Armoring wire: This highly durable armoring wire also uses corrosion prevention techniques. Frequently used in drilling formats, the armoring wire has extreme strength and protects against outside elements and corrosion.
- Land cable armoring wire: Bekaert land cable wire is an excellent option for underground power cables. It protects against harsh impacts and corrosion, ensuring the wire stays stable. In turn, the cables remain online and avoid damage from construction work or other interferences. Its corrosion resistance is due to cathodic protection strategies.
These wires are examples of cathodic protection in action.
Cathodic vs. Anodic Protection
Anodic protection is an additional strategy for preventing corrosion. Both cathodic and anodic protection are electrochemical processes that protect the metal from rusting and corrosion. However, anodic protection differs from cathodic protection in several key ways, such as:
- The protected metal becomes the anode: Anodic protection essentially takes the opposite approach of cathodic protection. In cathodic protection, the protected metal becomes the cathode in the electrical cell. In anodic protection systems, the opposite occurs — the protected metal acts as the anode.
- Suppresses reactivity: The goal of anodic protection is to keep the metal in a passive state. In its passivity, it does not react chemically and therefore does not corrode. Because of this, you can only use anodic protection with metals that already have relatively high passivity, such as stainless steel. In contrast, cathodic protection does not need a passive state and instead uses the current to stop corrosion from occurring.
- No different types: As discussed previously, cathodic protection has several types, such as galvanic and impressed current cathodic protection. However, anodic does not have other forms.
- Applications: Because anodic protection works only with high passivity, it is usually used for these types of metals, like steels. You can also use anodic protection for short-term solutions because it does not have the same longevity as cathodic protection. Anodic protection can withstand basic and acidic environments, so it is also useful in these applications.
Both of these are high-quality strategies for the prevention of corrosion overall. They are essential for keeping metal infrastructures safe.
Find the Right Wire for the Job With Bekaert
Bekaert is the leading supplier of steel wires and wiring solutions. Our innovative solutions and wire coatings reduce corrosion and improve adhesion. We set ourselves apart from competitors with premier customer service and superior offerings for clients across the globe.
Many of Bekaert's wires use cathodic protection to reduce and prevent corrosion. Our wide range of energy solutions keeps materials and structures secure. We can help you find the best wire for your needs and guide you through the entire process.
To get started, request a quote from us.