In an interview with WWD Associate Editor Caitlin Cunningham, Sherwin-Williams’ Kevin Morris shared information and insight regarding the expanding role coatings play in defending water/wastewater infrastructure.
Caitlin Cunningham: What are the most significant industry challenges for which protective coatings may prove to be an effective solution?
Kevin Morris: In the water treatment industry, there are no overriding factors that are contributing to the rate of corrosion other than age. These facilities need protective coatings to lower overall cost of operation through corrosion prevention, thus providing longer life cycles for equipment and structures. Concrete corrodes through many different mechanisms—erosion of the surface from abrasive flows or cavitation, chloride-induced corrosion of the reinforcing steel and freeze-thaw cycling, just to name a few. All of these are more prevalent now due to the age of these structures and can be stopped with the proper selection of protective coatings.
In the wastewater treatment industry, the most critical corrosion issue is hydrogen sulfide gas or sulfuric acid formation from microbial-induced corrosion (MIC). Population growth has taken these structures out of rural settings and into the urban sprawl. This has caused the municipal owner to have to address odor control issues, accelerating the effects of MIC. This phenomenon affects both steel and concrete and can eventually cause structural failure. The sewer collection system and primary treatment portion of the plant are the areas most susceptible.
Cunningham: What types of coatings are available on the market today? How can one determine which solution is the best fit for a specific project?
Morris: The workhorse coatings for water and wastewater applications are primarily epoxies. The greatest changes to coatings have come in the form of high-build, rapid-cure products, which reduce the number of coats and overall cost of a project by reducing labor costs.
The best method for determining which solution is the best fit for a given project or situation is through your local manufacturer’s field representatives.
Cunningham: What kind of coating maintenance requirements can an end-user or owner anticipate? Do you have any preservation advice to offer?
Morris: Protective coatings extend an asset’s life when they are properly maintained. Areas of a structure’s coating system that have been breached by things like weed eaters and rocks will begin to corrode and undercut the edge of the sound coating. Timely inspection of a coating system and touch-up to the damaged areas will provide an increased life cycle.
Consider the following example: You have several pieces of equipment that are currently heavily corroded and one fairly large asset that is showing minimal rusting. The substrate that has the worst appearance tends to receive the attention. How much worse can this piece of severely corroded equipment get? Will it last a couple of years until you can budget it back in? Or can you save the mildly corroded substrate by performing minimal surface preparation and over-coating? This should save money on surface preparation while extending the life of an asset that, if left to corrode, would require more surface preparation and money.
Cunningham: How do you anticipate the role of water/wastewater coatings will evolve in the coming decade?
Morris: The greatest change over the next decade will be restrictions over volatile organic compounds. These will dictate new product formulations and coatings specifications for projects for the foreseeable future, resulting in coatings that are higher in volume solids. This shift will force coatings applicators to become more sophisticated.
The secondary issue will be owners’ and consulting engineers’ quest to reduce the cost of capital improvements. They will be looking for coatings that provide the same performance with fewer applied coats. This factor will be critical during our current economic status but may lessen as the economy begins to recover.