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Balancing Act



Battling corrosion is a never-ending quest in which paint formulators need to supply their customers with solutions that balance performance with health, safety and environmental issues.



By Christine Canning Esposito



Published February 9, 2006
Related Searches: Corrosion Industrial Coatings
Corrosion. It is an issue that the general public doesn't think about on a daily basis-that is, until it affects their lives directly. And when it does, it often makes headlines and can prove quite costly (a major bridge closes unexpectedly for repairs, or worse, yet, collapses). That's why highway authorities-as well as product manufacturers,  engineers and contractors-expect their coatings suppliers to deliver anti-corrosion technologies that can prolong the life of their products, protect valuable assets and ultimately cut costs.

The bottom line in the battle against corrosion is that it costs everyone big money. The cost of corrosion to military equipment and infrastructure is estimated  from $10-20 billion annually, according to the U.S. Department of Defense. While that sounds staggering, it's just a small piece of the puzzle. As part of a federal study, CC Technologies and Nace International reported the direct cost of corrosion in the U.S. to be $276 billion per year, or roughly 3.1% of national GDP-and that was five years ago.

Coatings manufacturers Coatings World spoke with are battling corrosion in a number of industries from wastewater to general/light industrial to automotive. Each customer is on a constant vigil in the battle against decay, and each market has its own specific issues. Add to that an ever-changing landscape in terms of health, safety and environmental issues, and it's easy to see just how complex the anti-corrosion market has become.

Kansas City, MO-based Tnemec, the privately held manufacturer of architectural and industrial coatings, has been active in the wastewater marketplace, working to combat sulfide corrosion.

"Biogenic sulfide corrosion of concrete has become an increasingly pervasive problem leading to the breakdown of concrete in wastewater collection and treatment structures," said Vaughn O'Dea, who was named Tnemec's technical sales manager, water and wastewater in early 2005. "Sulfide corrosion is a bacteriologically mediated process in which hydrogen sulfide gas is oxidized in the presence of moisture to form sulfuric acid that attacks the matrix of concrete. The effect of sulfuric acid on concrete surfaces exposed to the wastewater environment can be devastating."

The precursor for sulfuric acid is hydrogen sulfide (H2S)  gas, and without H2S there would be no sulfuric acid. "Hydrogen sulfide has always existed in wastewater.  However, recent trends of water conversation, industrial pretreatment, and covering structures to control odors all have attributed to the increased sulfide corrosion," O'Dea said. In addition, hydrogen sulfide gas can also attack metallic components of wastewater systems such as steel grit collectors, bar screens, conveyors, skimmers and other ferrous metal substrates.  

Tnemec's weapon against this is Series 434 Perma-Shield H2S, a 100% solids, polyamine epoxy mortar designed to be trowel applied at 125 mils over concrete, and Series 435 Perma-Glaze, a 100% solids multifunctional polyamine epoxy designed to be applied to steel, concrete, or as a glaze coat over Series 434.  

In addition, Tnemec has developed a severe wastewater analysis (SWAT) to simulate the effects of elevated hydrogen sulfide gas and sulfuric acid on coating systems used in severe wastewater environments.  "Using the knowledge gained from our SWAT program, we can demonstrate the differences between coating formulations to customers," said O'Dea.

Showing the difference a specific coating technology can deliver in terms of savings and/or improved performance is critical for coatings manufacturers. To that end, companies are constantly tweaking their formulations to deliver better products.

Greenkote's latest development is a patented, proprietary corrosion resistant diffusion coating. The coating-which can also be applied as a pre-treatment before painting-supports the paint layer in the event of any damage, weakness or corrosion, offering a more effective corrosion protection solution, said Arie Laor, CEO of Greenkote. The coating provides an effective adhesion to paint while enabling a very low rate of corrosion under the paint layer, according to the company.    

Greenkote's solution has been implemented by MAG, a supplier of integrative mechanical and electro-mechanical assemblies for auto makers such as Volkswagen, Opel, Ford, GM, Peugeot and Citroën.

For its work with Volkswagen, MAG was required to use a zinc nickel process with a  cataphoretic dip painting treatment for the engine locks it provided the German automaker. Based on Volkswagen protocol, if MAG was to use that process, then they would have to ship all parts from their facilities in Israel to Germany to Volkswagen's exclusive vendor for this combined process and then ship them back to MAG in Israel for completion. Instead, Greenkote provided a solution that enabled MAG to do the work at its own facilities, which enabled it to complete the process in one location without overriding Volkswagen's exclusivity agreement.

According to Laor, Greenkote's process "reduced MAG's costs by 20%, improved logistics because it enabled them to complete the coating process in its own facilities and provided additional cost savings by improving corrosion resistance and because it was less likely to cause an environmental problem once the cars are junked (Europe's End of Vehicle Life legislation)," he said.  

Outside of automotive, Greenkote-established in 1999 as Summet Hi-Tech Coatings Ltd.-has had its products specified on some rather high profile structures, including Heathrow Airport's new terminal five, the Oval cricket stadium and the Wembley stadium bridge  in the UK. Now, the company has set its sites on the U.S. market, having established a new  sales and support team there two years ago.  According to Laor, Greenkote  is in "several negotiations with leading U.S. companies for licensing/JV agreements."

Safety First

One area in which fighting corrosion is absolutely critical is infrastructure, especially bridges. Premature failures hit government coffers hard, but there is also the risk of injury (or worse) to those who commute on them daily.

In the UK, Edinburgh's Forth Road Bridge, which opened to traffic in 1964, was originally meant to have a lifespan of 120 years. But a recent engineering study commissioned by the bridge's operator found that corrosion on the main cables was so severe, the bridge would have to be closed to trucks in 2013 and to cars by 2019. Estimates for a replacement bridge are in the area of Ł1 billion, according to reports in local papers.

To avoid such troublesome and expensive premature failure in all types of applications, the entire supply chain needs to come together to develop better solutions. On the coatings side, that means raw materials suppliers and coatings formulators need to deliver technologies that offer superior protection but still meet regulations.

This trend was echoed by Tony Gichuhi, R&D manager at Halox. "There is a steady shift toward implementing heavy-metal free anti-corrosives because of the human and environmental stigma associated with hexavalent chromates, cadmium, zinc and barium-based corrosion inhibitors," commented Gichuhi, who said his company is designing heavy-metal free products and educating customers on the best ways to reformulate protective coatings with non-toxic corrosion inhibitors. In addition, Gichuhi said there is growing demand for new technologies, such as hybrid corrosion inhibitors that maximize anti-corrosion efficiency without adding cost to paint formulations.

Offering safer technologies is a goal for all coatings formulators, especially for those that operate in the EU and elsewhere where deadlines loom for solvent reduction and other safety and health issues.

For SigmaKalon, the goal is to balance performance and environmental issues-and  still fulfill customers' tough requirements. "We are very aware of health concerns and CMR concerns. We want to be proactive and respond to customers concerns," said Philippe Desberg, general manager, anti-corrosion division, SigmaKalon France. According to Desberg, SigmaKalon is looking to replace current formulations that have "warning labels" as well as offer lower VOC products. "We are actively looking at alternative solutions. We are working closely with labs of SigmaKalon and Freitag to develop solutions to the progressive and unavoidable trend to lower VOCs. With anti-corrosive coatings, upcoming legislative, health and environmental issues will continue to be the drivers."


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