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SURFACE 2018

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COATINGSPRO SURFACE PREP 2018 15 Graco Inc. 88-11th Avenue Northeast Minneapolis, MN 55413 (612) 623-6000 www.graco.com Three Tips to Prevent Flash Rust Flash rust refers to the very rapid onset of rust on a metal substrate and according to the SSPC Protective Coatings Glossary (PCG), flash rust is "rusting that occurs on metal within minutes to a few hours after cleaning is complete. e speed with which flash rusting occurs may be indicative of salt contamination on the surface, high humid- ity, or both." W hen it comes to flash rust, there are a couple of differ- ent variations: rust-back and re-rust. Rust-back occurs when there are already contaminates on the surface of a substrate. For example, if you expose bare steel to high humidity or moisture in the air (i.e. you're near a coast), that's when rust-back will occur. is is typically something that you're going to see after dry abrasive blasting, or using power tools such as needle guns, to clean the surface. Re-rust, or rust bloom, refers to new rust and occurs evenly over a large section of the surface. It's similar to flash rust, but whereas flash rust will develop over minutes or hours, rust bloom can take days to develop. As wet cleaning methods have increased, so has the prevalence of flash rust - and the need to look at solutions or strategies to prevent it. Here are three tips to help prevent flash rust. Use a Clean Water Source One of the big contributors to flash rust is water quality. Some companies may need to pull water out of a well on a jobsite, and as a result, the water has a very high chloride content. After oxygen, chlorine is next most reactive element. Using a very clean water source, such as water filtered using distillation or reverse osmosis, can help prevent flash rust - and even reduce the need for rust inhibitors and other protec- tion methods. Ensure the Substrate is Free from Contaminants Salts and chlorides are big contributors to contamination of the surface, but in a lot of cases what you' ll find is that there were may be some particles of rust when the steel was formed. Once they are exposed they can very quickly start to bleed rust and you will experience rust-back rather than flash rust. Several different manufacturers make corrosion inhibi- tors or surface passivators that can be mixed with water and used for wet abrasive blasting. is allows the water to get deep into the profiles with wet or vapor abrasive technol- ogy and it will flush the salts and chlorides out of those deep grooves, leaving a much cleaner surface. Add a Rust Inhibitor if Wet or Vapor Abrasive Blasting Some inhibitors on the market will evaporate and actually leave the surface very clean of any contaminates while others are designed to create a film to prevent the air from getting to the surface to begin the oxidation process. ere are many varieties of rust inhibitors, including a few popular ones used with wet and vapor abrasive blasting. To learn more, check out the articles on blastjournal.com or visit graco.com/ecoquip. Company Profile: Graco Inc. SPONSORED CONTENT

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