So far in this series of posts on corrosion, we’ve defined corrosion, differentiated between different types of corrosion and assembled some facts and figures regarding what corrosion costs the American economy. Now we’ll turn to how corrosion can be prevented. As you may or may not know, this is what we would call our sweet spot.
Methods of corrosion prevention
The goal of corrosion prevention is to preserve the integrity of an asset, as well as to preserve the integrity of any materials an asset may contain. In the case of a water storage tank, this would mean keeping the water inside potable by keeping it from becoming contaminated. In the case of a storage tank holding more volatile contents, such as jet fuel, the corrosion prevention solution must be resilient enough to protect the storage container without reacting to the contents inside.
According to NACE, the following are the four most common methods for the prevention of corrosion:
- Corrosion inhibitors- Inhibitors are a class of chemicals that have the ability to slow the corrosion of a metal or alloy. They are typically added to electrolytes in small amounts, often in closed systems such as tanks and piping. This type of corrosion prevention is common in the oil and gas extraction and processing industries.
- Cathodic protection- This form of protection makes use of metals more susceptible to corrosion—such as magnesium, zinc or aluminum—as a sacrificial barrier to protect an asset from corrosion. These sacrificial metals, or anodes, corrode preferentially to the substrate they protect, keeping the asset corrosion free.
- Material selection- Prevention by material selection and design seeks to engineer out the most common sources of corrosion. This can mean manufacturing from metals less reactive than steel, such as platinum or stainless steel, or by avoiding corrosion “hot spots” during the design phase. No metal is completely immune to corrosion, but some are able to resist the process for longer. Obviously, price becomes a major consideration when evaluating this method.
- Coatings and linings- By far the most common strategy for corrosion prevention, coatings and linings are often used in conjunction with cathodic protection for optimal protection. The type of coating or lining used, and the thickness at which it is applied, vary greatly and must be tailored in order to most effectively fight corrosion given the environmental conditions of an asset.
Corrosion control programs
Whichever method of corrosion prevention is right for an asset, one or more of the above strategies will play a part in a broader corrosion control program. This program will detail the specifications for the prevention method to be deployed, the surface preparation necessary to effectively implement the method and provisions for quality assurance and quality control.
Another aspect of a comprehensive corrosion control program will address the issue of contractor selection. But before an application contractor is selected, asset owners need to do their research. That’s why we’ve put together this guide for what to consider when hiring an industrial painter. It’s not meant to be a stand-in for all the research that should precede making a hire, but it’s a good start to this crucial portion of a comprehensive corrosion control program.