Protect Facilities from Corrosion
EP Editorial Staff | December 1, 2019
Chemically bonded phosphate ceramic (CBPC) coatings provide durable protection from atmospheric and chemical corrosion.
Corrosion is the biggest single cause of plant and equipment breakdown, including machinery, vessels, structures, supports, and pipelines. While atmospheric corrosion, in the form of air and water, is the main culprit, environmental factors such as high temperatures, pressures, and harsh substances, chemicals, and gasses can also accelerate the corrosion of carbon steel and other metals.
Beyond marine environments exposed to salt spray or compounds that cause corrosion, common gaseous industrial air pollutants, such as sulfur dioxide, ozone, and nitrogen dioxide, can induce corrosion. So can exposure to industrial chemicals such as chlorides, acetic acid, and formaldehyde.
“There is a huge need for an anti-corrosion coating that can be applied in areas where conventional coatings tend to fail,” said Joey Taylor, president, IPI Inc., an Elkview, WV-based paint/coating contractor for commercial and industrial construction. “On certain projects, chlorides need to be removed in order to meet peak performance. But in most cases, this can be cost prohibitive.”
Fortunately, for industrial facilities with assets prone to environmental corrosion, a category of tough chemically bonded phosphate ceramic (CBPC) coatings is helping to stop corrosion, ease application, and reduce production downtime.
When aluminum is recycled, it is melted to separate the pure metal from the impurities. The process creates a waste product called salt cake, which contains compounds that can promote corrosion. As a result, typical barrier-type anti-corrosion coatings, such as polymer paints, can fail prematurely. When the paint is scratched, chipped, or breached, corrosion promoters can enter the gap between the substrate and coating. The coating then acts as a greenhouse, trapping the corrosion promoters and allowing corrosion to spread under the coating.
When an aluminum recycling plant in West Virginia required corrosion protection for its operation, it sought a long-term term solution that would not require frequent recoating, according to Taylor, who was involved with the project.
“The recycling plant was not having much luck with conventional anti-corrosion coatings, which only lasted about three or four years,” he said. “Anyone trying to protect their assets from corrosion wants their coating to last much longer than that.”
To provide long-term corrosion protection in a tough environment, the aluminum recycling plant and Taylor turned to EonCoat, Raleigh, NC, for a spray-applied inorganic coating of the same name. In contrast to traditional polymer coatings that sit on top of a substrate, the CBPC coating bonds through a chemical reaction with the substrate. The coating can be applied over flash-rusted, damp steel. An alloy layer is formed. This makes it impossible for corrosion promoters such as oxygen and humidity to get behind the coating the way they do with ordinary paints. Although traditional polymer coatings mechanically bond to substrates that have been extensively prepared, if gouged, moisture and oxygen will migrate under the coating’s film from all sides of the gouge.
Visible in scanning-electron-microscope photography, EonCoat does not leave a gap between the steel and the coating because the bond is chemical rather than mechanical. Since there is no gap, even if moisture was to get through to the steel due to a gouge, there is nowhere for the moisture to travel. A ceramic layer that resists water, impact, abrasion, and chemicals, as well as fire and temperatures to 842 F covers the barrier.
For IPI Inc., EonCoat was sprayed on two industrial dust collectors (one 60,000 cfm and one 40,000 cfm), including four tanks as large as 40-ft. tall and associated ductwork.
Cost advantages with coatings such as EonCoat extend beyond corrosion resistance. Coatings consist of two non-hazardous components that do not interact until applied with a standard industrial plural spray system such as those used to apply polyurethane foam or polyurea coatings. Since CBPC coatings are inorganic and non-toxic, there are no VOCs (volatile organic compounds), no HAPs (hazardous air pollution), and no odor. The water-soluble, non-flammable coatings can be applied safely even in confined spaces, or when adjacent parts of a plant continue to operate.
Quick return to service minimizes facility downtime. The time saved on anti-corrosion coating projects comes from simplified surface preparation and expedited curing time. With a typical industrial coating, near-white-metal blast cleaning (NACE 2 / SSPC-SP 10) prepares the surface. With the ceramic coating, only a NACE 3/SSPC-SP 6 commercial blast cleaning is typically necessary.
“With EonCoat…once you have a clean substrate surface, free of mill scale and coating, it will not hurt it to let it flash rust,” explained Taylor. “So, you can continue coating [the next day] without having to re-blast the substrate, re-prime it, or set up and teardown paint equipment. You can continue to blast the entire 12-hour shift. That saved us about a 50-hour workweek on the project.”
“We were able to complete the project in nine weeks, including substrate preparation, spraying, and adding a high-performance topcoat, with minimal disruption to the plant’s operations,” reported Taylor. EP
For more information, visit eoncoat.com.