Element No. 8, oxygen, is essential to almost all life on this planet, but its high reactivity endows it with a dark side. It easily combines with most metals to produce an oxide, which is generally undesirable in the industrial arena. There are some exceptions, the most common being lead and aluminum. The oxide that forms on these metals is relatively transparent and dense enough to protect the substrate from further attack by oxygen molecules.
In general, water, so common in nature, accelerates oxygen attack – corrosion – on susceptible metals. The best that a plant professional can do is stem the tide, but it requires continuous diligence to protect the capital assets that provide your livelihood. Years of empirical testing and applied theory have led to several technologies that minimize corrosion. Many of them are highlighted in the digital morass we call the Web. So, join me in search of practical, zero-cost, noncommercial, registration-free resources that will keep your plant looking like a shiny, new nickel. Remember, we search the Web so you don't have to.
Getting off the ground
We’re accustomed to believing, sometimes incorrectly, that nasty industrial air pollutants cause excessive corrosion on any metallic item placed outdoors. According to the first Web site citation, the corrosion rates in cities we associate with heavy industry aren’t nearly as bad as the rates at venues we’d consider a bit more Edenic. For example, the rate in Pittsburgh is 1.2 mils/year, Cleveland suffers with 1.5 mils/year and East Chicago rots at 3.3 mils/year. Contrast those numbers with the 42 mils/year you’ll experience at the Kennedy Space Center. With the reliability of the shuttle and its ground support hardware being so critical to a safe launch, one wonders why NASA set up shop there. The good news is that NASA’s Corrosion Technology Laboratory knows how to prevent the metallic degradation that can drop into your back yard the stuff intended for orbit. And, NASA will reveal some of what it knows if you launch your weightless mouse around http://corrosion.ksc.nasa.gov. The “Corrosion Fundamentals” tab offers a brief overview of the electrochemistry involved, the multiple types of corrosion, corrosion control and a list of additional sources of information. The latter option has a link to NASA-KSC TM-584C, "Corrosion Control and Treatment Manual," a 36-page document that discusses applicable MIL specs and suitable products. The “Resources” tab gives access to publications, the scholarly works written by engineers at the lab.
Dollars and rust
Not only is corrosion a pain in the patootie, but it comes with a cost that degrades your industrial financial performance and, if addressed improperly, enhances governmental budget shortfalls. Corrosion proceeds in only one direction, and it takes cash to hold back that real-world example of rising entropy. The quantity of cash needed involves some staggeringly large numbers. At least one company, CC Technologies, Dublin, Ohio, tracks the financial effect of corrosion on its Web site, www.corrosioncost.com/home.html. It reports that production and manufacturing face more than $17 billion in corrosion costs, and that only accounts for nine select industrial categories. Visit the Web site if you want details about the cost of corrosion on utilities, transportation, infrastructure and government, plus, of course, the nine industrial elements. The tab tagged as “Corrosion Control Methods” will show you the methodology used to develop the cost data, but not actions you can take to control rusting.
A plant subsystem that might fall victim to the ravages of unnecessary corrosion is the boiler and the various pieces of hardware in the steam system. By definition, boiler corrosion starts with elevated temperatures. After that, it doesn’t take much in the way of incorrect pH, dissolved or suspended solids, oxygen, high velocity and impingement to set the scene for corrosion-induced reliability problems. You might be able to get a little more performance out of your boiler if you read the material that GE Water & Process Technologies, Trevose, Pa., posts on the Web. The company provides the full text of a 40-chapter book that explains the mysteries of water treatment, boiler systems, cooling water systems, chemical feeders, wastewater and gas cleaning systems, and water analyses. This isn’t light reading – the explanations are fairly technical. Go to www.gewater.com and enter the phrase “handbook of industrial water treatment” in the search box. Somewhere in the results will be an entry showing the handbook name, but without any reference to a particular chapter or topic. That’s the link you want. If it doesn’t load properly when you click on it, try again with a right-click to open the link in a new window. Four of the chapters about boilers are explicitly about corrosion, whereas one chapter in the cooling water section mentions it. Other chapters might have additional information about the topic.
In the good old days, researching a technical topic meant a trip to the reference section of a library if you lived in a larger town, or a lot of searching with phone calls and catalogs if you didn’t. That approach is snail-like compared to the Web, which allows us to dig deeply in as many places as necessary in search of the information that resolves the question. The most useful Web sites for this purpose provide full-text access to books that address corrosion. We found a winner this month in the Web site associated with an initiative called the Whole Building Design Guide, which covers so much territory that you should explore it on your own when you get bored sitting at a desk.
In the interim, if you’re partial to using industrial coatings to prevent corrosion, you can access the online, 250-page “Unified Facilities Criteria - Protective Coatings and Paints” merely by visiting http://artikel-software.com and entering the phrase “protective coatings” in the search box. You’ll learn about coating compositions and curing mechanisms; environmental, occupational and safety issues; coating selection; coatings for specific uses; surface preparation; application; writing painting contract specifications; painting inspection; inspection instruments; paint failure analysis; maintenance painting and safety practices. Use this site when you want to complete a project that’s in accord with various military specifications.