Corrosion is a chemical reaction that occurs when a refined metal converts to a more stable form such as its oxide state, leading to deterioration. For instance, iron corrodes when exposed to oxygen and water, creating red iron oxide, commonly known as rust.
Corrosion can cost industries in the United States up to $170 billion a year, more than half of that in the oil and gas industry. Reducing the corrosion rate can extend the life of industrial metal components, which can in turn bring down maintenance costs and have other benefits. Protective anti-corrosion spray coatings can help prevent corrosion in such equipment as steel or concrete tanks or other metal surfaces.
What Are the Types of Corrosion?
There are multiple types of corrosion, such as uniform or “general attack” corrosion which often occurs evenly over a material surface. Pitting corrosion is often the most destructive type as it involves cavities or holes in a surface that can lead to structural failures. Crevice corrosion takes place in areas that receive less oxygen, such as under bolt heads or washers. Intergranular corrosion takes place adjacent to or along the grain boundaries created when an alloy solidifies.
Galvanic or two-metal corrosion involves different metals that are immersed in saltwater or other common electrolytes. Stress corrosion or “SCC” (stress corrosion cracking) takes place in corrosive environments where ductile metals fail under tensile stress.
In addition, selective leaching takes place when the corrosion process removes one element from a solid alloy, such as zinc from brass alloys.
What is the Main Cause of Corrosion?
Corrosion is an electrochemical reaction that generally takes place when all or most of the oxygen atoms on a metal surface lose electrons to the surrounding environment, such as the air or water. As the oxygen atoms are reduced, an oxide such as rust forms with the metal. Metal can also corrode when reacting to electrical currents, bacteria or dirt. Corrosion can also occur when steel or other metals are placed under excessive stress and crack.
Before (left) and after (right) applying chemical and corrosion resistant coatings
What Are the Signs of Corrosion?
When corroding, metal objects can show such visible signs as superficial surface rust and more penetrative scale rust. Active corrosion often involves powdering or flaking of the metal surface, so a metal object or surface surrounded by loose powder or flakes may be actively corroding.
Iron corrosion may involve the “sweating” of brown or yellow droplets on the metal surface.
A galvanized steel surface may show signs of both the white corrosion of zinc oxide, caused by the oxidation of a zinc coating, as well as the spots of red rust as the steel base is corroded.
Copper alloys exposed to elements frequently show a greenish coloring during corrosion.
When steel reinforcing bars within concrete buildings begin to corrode, it leads to the degradation of the concrete.
How Do You Protect Steel From Corrosion?
Perhaps the most effective way to avoid corrosion is to build with a corrosion-resistant metal. Aluminum or stainless steel, when used properly, can reduce the need for corrosion protection.
One way to protect steel from corrosion is to control its environment to reduce exposure to seawater, rain or the presence of such chemicals as chlorine or sulfur that can cause corrosive chemical reactions.
Perhaps the most cost-effective ways to prevent corrosion is the use of protective coatings, which prevent the transfer of the electrochemical charge from the metal surface to the corrosive substance in the environment. Coatings can come in paint and powder forms.
“Sacrificial coatings” are metal coatings designed to be more likely to cause oxidization while protecting the integrity of the primary metal. For example, cathodic protection can involve coating an iron alloy steel with zinc, or galvanization.
Before (left) and after (right) repairing holes in tank using our structural coating system
The Benefits of Anti-Corrosion Spray Coatings for Industrial Applications
Anti-corrosion sprays can be applied to substrates such as steel, concrete, asphalt and more. An anti-corrosion spray can protect, repair or seal steel or concrete tanks that are subject to chemical spills or exposure.
An effective corrosion resistant spray coating provides corrosion protection and adhesion while proving resistant to fatigue and exposure to water. The best spray coatings for many industrial applications are long-lasting, easy to apply, cost effective and high performance, without leading to adverse environmental reactions.
With our systems, tanks and equipment can be returned to service within hours, not days. Our spray applied elastomer system is comparable to many epoxy systems. With faster set times, and outstanding adhesion (primer not necessary), our products offer an operational advantage and cost saving approach to rehabilitating your equipment and structures.
- Steel and concrete internal tank coatings
- Primary containment for interior tank linings
- High splash or spill areas with direct chemical contact
- Water Treatment chemical processing
- High concentration chlorine contact chambers
- Leachate runoff tanks
Advantages of Chemical Resistant Coatings
- Elongation allows movement with the substrate
- 3000 PSI very strong and adds strength to substrate
- Quick back to service
- High abrasion resistant
- Apply in thicknesses of 60-1000 mils
- Bridge cracks and voids
Examples of product use include: ethanol, methanol, gasoline, hydrochloric acid, jet fuel, phosphoric acid, sodium hydroxide, sulfuric acid, and much more.