in 2001 a study conducted by CC Technologies Laboratories, Inc. estimated that corrosion in the United States cost an estimated 276 billion dollars a year. This equated to approximately 3.1% of the nation’s Gross Domestic Product (market value of all final goods and services made within the borders of a nation in a year) at the time. When you consider this study was conducted nine years ago you begin to wonder what the cost of corrosion in the U.S. is today.
On a personnel level, the question beckons – “do we know what corrosion is costing our respective companies”? What is the decreased reliability of machinery, equipment and structures from corrosion costing us? What is the potential cost of lost revenue due to disruption of services? What are we spending on labor and equipment for corrosion repair and maintenance?
I believe when we stop and give some thought to such things as: what is the leaking cooling tower costing us, the potential liability associated with spalling concrete in the parking garage, the likely repercussions of hydrostatic water issue in the elevator pit saturating the machinery, etc., we quickly come to the realization corrosion is costing us much more than we ever imagined. So what do we do about it?
I believe we will all agree that if we are aware of an issue(s) and have a basic level of knowledge regarding the challenge(s) then we are better prepared to deal with it when it occurs. To this end, let’s define corrosion and quickly identify the most basic forms we are prone to encounter in our industry on a daily basis.
Generally, corrosion encompasses the process that involves the deterioration of metal. Ultimately corrosion is the chemical wearing away of a metallic substrate. The most common forms we will probably see in our industry are as follows:
General/Uniform Corrosion – Example: Rusting Steel – The metal loss occurs at essentially the same rate (uniformly) over the metal surface (no pitting/deep pockets of corrosion are evident), hence the term uniform corrosion. Uniform corrosion is considered to be one of the most common forms of corrosion and is relatively easy to address through the thoughtful selection of materials, coatings and corrosion control methods. Although unsightly, uniform corrosion is generally insignificant, in that it is usually addressed prior to becoming an issue.
Atmospheric Corrosion – Degradation of a material as a result of coming in contact with substances present in the atmosphere. Atmospheric corrosion occurs on a steel surface when the steel becomes wet from rain, humidity, etc. and the moisture is combined with impurities / pollutants present in the air; such as: chlorides from sea air and/or industrial pollutants (carbon dioxide, sulfur, etc.)./ In moist environments where atmospheric impurities are high, corrosion can occur rapidly. The corrosion can have marked visual differences dependent on the location and the environment/atmosphere. For example, in an atmosphere near the ocean (chlorides) or in an industrial area (carbon dioxide) the surface can have a very rough corrosion face with evident pitting present, where in a different environment the corrosion might be smoother. Both are certainly worthy of concern; however, keep in mind the chemical reactions taking place (due to the atmosphere) can give rise to different corrosion mechanisms and therefore a different appearance.
Galvanic Corrosion/Bi-metallic Corrosion – A galvanic reaction occurs when two dissimilar metals are in contact with one another in an electrolyte. The end result is that the less noble metal (anode) will sacrifice itself to the more noble metal (cathode). The more disparate the metals are in the galvanic series of metals the more rapidly the corrosive action will occur. As an example, zinc anodes (very low on the galvanic series) are often used to intentionally create a galvanic reaction so they (zinc anodes) will sacrifice themselves in lieu of the steel (ship hull, pipeline, etc.) they are protecting. However, many times galvanic reactions are set-up unintentionally, which often leads to severe consequences.
Concrete Corrosion/Corrosion in Reinforcing Steel – Needless to say, concrete itself doesn’t corrode; however, a vast majority of the concrete used in buildings and structures contains reinforcing steel. In instances where the quality of concrete is poor (therefore highly permeable to moisture), calcium chloride was used as an additive (due to having to pour concrete in cold weather), the thickness of the concrete over the reinforcing steel was not adequate to protect the steel from moisture, corrosion of the reinforcing steel is often a major problem. Once the reinforcing steel begins to corrode the rust expands and flakes thereby cracking the concrete and delaminating it from the reinforcing steel. The cracking then allows further moisture to penetrate the concrete exacerbating the problem.
The preceding is a very short and certainly not exhaustive list of the corrosion issues one might see in a building on a daily basis. Keep in mind complete books have been written on the subject of corrosion, there are entire fields of study on the subject and of course there are people who have chosen to make the identification and prevention of corrosion their life’s work. However, if this short article has made you more aware of corrosion and what it might be costing your organization, it has served its purpose.
Now that we have made you more attentive of the potential corrosion issues in your facility and the challenges they present, what do you do about them? There are a number of options available ranging from traditional paint to ultra-high performance polymer composite rebuilding and coatings systems to corrosion inhibitors, alloys and catholic protection.
Over the course of the last decade a great deal of research has gone into the development of a new breed of highly advanced polymer composite coating and rebuilding systems. Some of these systems are quite unique as a result of their physical properties, in that some possess extremely high bond strengths (often in excess of the rate at which ferrous corrosion/rust grows), are 100% solids (they have no odor), can be used to rebuild (paste grade components) and protect (liquid grade) vital machinery, equipment and structures from the effects of erosion, corrosion, wear, chemical attack and hydrostatic water transmission.
Hopefully we have provided you with the desire to begin to explore what corrosion is costing your organization and some of the basic tools to evaluate your findings. As you explore potential remedies for your corrosion challenges, keep in mind every solution has its application. So look at all your options, be curious, and make good informed decisions based on long-term results and you will be a winner in your battle against corrosion.
Submitted by: Kevin Padera, Enecon.