After fabrication, every utility structure made from carbon steel undergoes some type of protective coating such as galvanizing and/or painting. Utility structures made with 588 weathering steel form a patina over time that protects the steel from rusting.
Galvanizing has been around for a century (if you’re not familiar, then read What Everyone in the Hot-Dip Galvanizing Industry Should Know.) These protective coatings improve the overall lifespan of the steel, but sometimes embedded steel poles or casings may need an additional protective coating to combat soil conditions.
Chemline? Corrocote? What’s the difference?
While both Chemline and Corrocote offer below grade coatings that can be applied to direct embedded steel structures or casings to protect against soil conditions, the main difference is that Chemline is an American made product and Corrocote is formulated in Canada.
Chemthane, which is the below grade coating produced by Chemline, can be applied to the embedded portion of a galvanized or weathering steel pole, and come in a variety of colors. Typically, the standard coating is Chemthane 2260, which is an equivalent to Madison Chemicals Corrocote 2 Classic.Chemthane 2260 forms a hard polymer film that acts as an adhesion and is abrasion and chemical resistant. This coating provides corrosion protection with cured films between 18 and 30 mils (0.5-0.75mm) in thickness. The more common application is sprayed with a spray gun,using plural component painting equipment.
For galvanized structures it’s not mandatory to apply this coating, however, the Chemthane provides an extra barrier to help protect the embedded portion from soil conditions. With weathering steel embedded structures this coating is highly recommended since the self weathering properties can’t perform underground. In order for weathering to perform, it must be exposed to oxygen and go through wet/dry cycles that are needed to form an oxidized, or rust, protective coating. Also, if the weathering structure is not hermetically sealed and in an area with a lot of ground water, then in some cases, it’s recommended to coat the inside with Chemthane to protect the structure if water seeps in.
The standard colors for Chemthane 2260 are black and brown, but depending on things like aesthetics or safety precautions, they can come in a variety of colors, as well as safety colors.
Something to keep in mind is that these coatings are sensitive to direct sunlight and will chalk and become brittle if left above ground for longer than 30 days. So, for customers that store above ground for a longer period of time, we recommend an additional coat on top of the standard Chemthane 2260, which is the Chemthane 3300 UV protection coat. Sometimes, customers request to have the Chemthane 3300 applied over the 2260 even if poles or casings are installed right away to provide extra protection to the portion above, below or at ground line.
Chemthane 3300 is an acrylic polyurethane finish coating that’s formulated to provide an extreme durable high performance finish that is UV stabilized, chemical resistant with a high gloss finish and color retention.
*Side note: If you need a specific color for the 2260 like the safety red but also decide to apply the 3300 UV protection, note that it will not affect the color because the 3300 is a clear coating that goes over the 2260.
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