Aging utility industry infrastructure beset by corrosion problems

Corrosion is taking its toll on the gas, electric, water and sewer industries. A new report by Power Engineering contributor Del Williams estimated that a large share of carbon steel structures is now between 40 and 100 years old, which means a dramatic increase in repair and treatment costs is likely for the years ahead.

EPRI, the electric power research organization, gave an estimate of expenses incurred solely by the power industry based on a study from 1998 which is still being used as an industry benchmark. EPRI said that the price tag of corrosion for electric utilities totaled $17.3 billion, of which 22% might not have been necessary to spend if the industry had been able to employ practical, cost-effective approaches.

Where does corrosion occur? The U.S. National Institute of Building Sciences names five areas that typically experience corrosion problems: water lines and storage facilities, electric transmission and distribution infrastructure, steam distribution systems, telecommunications support, and storm and wastewater systems. Citing studies by the U.S. Federal Highway Administration and NACE International, NIBS said that utilities, which supply electricity, gas, water, and telecommunications services, account for the major percentage of corrosion costs each year, with drinking water and sewer systems representing the largest share.

A recent 2018 study by NACE International, the corrosion society, predicted corrosion costs of $2.5 trillion worldwide, which represents about 3.4% of global GDP. As NACE explained, these expenses usually don't take into account individual environmental or safety consequences.   

Electric transmission linesCorrosion in aging infrastructure means added maintenance costs for utilities.

Phosphate ceramic coatings being touted as corrosion solution

Williams said that conventional corrosion treatments utilizing barrier-type coatings such as epoxies or polyurethanes are generally applied more than once. One drawback is that this method can set up a type of greenhouse effect, capturing water, oxygen and other corrosion facilitators underneath the coating surface, allowing the corrosion to spread further. The damage can sometimes be nearly undetectable, leading to premature component failure and early replacement. As a result, the coatings usually have to be reapplied, incurring a significant cost in preparation, application and lost productivity due to facility downtime.

The alternative to this approach is a new generation of anti-corrosion coatings known as chemically bonded phosphate ceramics, according to Williams. The benefit of CBPCs is their ability to dramatically extend facility and infrastructure life while improving safety, cutting downtime and decreasing maintenance expenses.  

How the new treatment works

Williams explains that compared to traditional polymer coatings that remain on the surface of the metal, CBPC bonds chemically with the substrate. Minor surface oxidation serves to enhance the chemical reaction, creating an alloy layer. This prevents oxygen and humidity from infiltrating the coating as other painted coatings have a tendency to do. Once the underlying steel is stabilized through this alloying process, it loses the ability to react to the exterior environment, thus inhibiting further corrosion.

Plus, electron microscope inspection shows that the CBPC treatment does not produce a gap between the coating and the steel because the bonding is chemical instead of mechanical. With no gap, there would be no space for any moisture to migrate, even if it were possible for it to penetrate the coating through an accidental scratch, gouge or other damage. 

Preparation-wise, a CBPC treatment can be applied in a single coat and requires almost no curing time, compared to days or weeks for epoxy or polyurethane paints. The CBPC makes it possible for equipment to be returned to service in as little as one hour. The end result is an expected lifespan that is three times that of traditional coatings, which is much more cost-effective in the long run for utilities.