Corrosion challenges abound throughout our nation's water and wastewater infrastructure. For wastewater professionals, some of the corrosion challenges they face may include biogenic sulfide corrosion, carbonation of concrete (both atmospheric and aqueous phase), chloride-induced reinforcing steel corrosion and physical forces such as abrasion, erosion and cavitation. On the potable water side, professionals face challenges with protecting structures from corrosion caused by steel under stress (resulting from welding, bending or forming, for example), dissimilar metals, free chlorine in the vapor space and other abrasive and corrosive conditions that might be present.
There are several proven techniques that, when used effectively, help mitigate corrosion and its destructive forces. One of these methods involves the use of protective coatings and linings. In immersion service, linings provide barrier protection for the substrate and help protect the structure from the aggressive service in which it operates. The category of protective coatings and linings is rather broad, as there are many generic types (and specific formulations) that are commercially available.
CHOOSING THE RIGHT PRODUCT FOR THE JOB
So how can owners, consultants, engineers, specifiers and contractors ensure that they select the suitable coating or lining for any given service environment? Looking at the available generic types (such as epoxies, polyurethanes and polyureas) one must consider the advantages of each—along with any application challenges—to choose the correct product for the project.
One viable option for corrosion protection in immersion service is to use 100% solids aromatic polyurethane linings. These materials have been used extensively in water and wastewater environments for 20+ years. They have been used in wastewater collection system structures, such as lift stations and manholes, and within all phases of the wastewater treatment process, including the more abrasive areas of plants such as headworks structures, digesters and membrane bioreactors. These materials have been used in potable water service for lining applications in water storage tanks (primarily steel) and structures within a water treatment plant (concrete and steel).
Holston Munitions Plant, BAE EQ Basin, from the top. PHOTO: COURTESY OF CARBOLINE
Polyurethane linings have also been used with geotextile fabric to repair leaking concrete joints in water storage tanks where water stops were left out and in applications over severely corroded pitted steel. Additionally, there has been a recent uptick in usage for lining carbon filtration vessels and restoring (and further protecting) galvanized bolted tanks. Because 100% solids aromatic polyurethane linings are very flexible in their use, they can be specified for various applications.
Flexibility happens to be one of the many valuable physical features of polyurethane linings. Elongation can be desirable, especially when lining structures that may experience slight movement and/or thermal cycling. These linings also offer good resistance to impact and abrasion, both of which come into play in wastewater structures, such as grit chambers, influent channels and wet wells, and potable water storage tanks demanding resistance to ice abrasion, among other things. Their ability to be applied in greater thicknesses in a single lift and their fast return to immersion service make these materials ideal for either new construction or rehabilitation projects, especially those that might have to be fast-tracked. Another key benefit is the ability of polyurethane linings to be applied (and cured) at temperatures less than 40 degrees Fahrenheit, which can be a significant challenge for epoxy linings.
LEARNING FROM EXPERIENCE
Over the last decade, Robert Boswell of Boswell and Reyes International LLC has been specifying and inspecting Carboline Reactamine 760 and Reactamine 760 HB (high build) 100% solids aromatic polyurethane linings for use in water and wastewater environments.
"Polyurethane linings perform well in all of the environments in which I specify them,” he said. They work especially well in water storage tanks, particularly in roof structures. These materials are second to none when it comes to flexibility, making them ideal for use in large storage tanks that are prone to a lot of movement in the roof structure and roof plates.
“My customers end up with an excellent-performing material that helps to extend the service life of their key assets. Abrasion resistance, flexibility, fast return to service, the ability to apply these materials at very high film builds and no volatile organic compounds are just a few reasons these materials are so often specified on projects for many of my key clients."
CASE IN POINT
Check out this timelapse vidoe of applicators using Reactamine 760 on a storm basin at the Indianapolis International Airport.
Individuals working to protect structures against the corrosive forces present in the water and wastewater infrastructure have at their disposal a plethora of tools for their protective-coatings-and-linings toolbox, but the Reactamine 760 series can effectively serve as a multi-tool (like a utility wrench)—usable in multiple scenarios. While a single product may not address every scenario in water and wastewater environments, the Reactamine 760 lineup comes close!
Learn more about Reactamine 760 and Reactamine 760 HB.
Claims or positions expressed by sponsoring authors do not necessarily reflect the views of TPC, PaintSquare or its editors.