$30,000,000,000! For the economically challenged, that reads thirty billion dollars. It really doesn’t matter who might be counting it; that’s a lot of money. It happens to be the amount that the Federal Highway Administration estimates that corrosion costs the nation’s transportation industry and its infrastructure every year.
Corrosion, of course, has plagued the transportation industry since it began using ferrous metal in vehicles, that is to say as early as the days of wooden wagons with their hand-forged iron parts. And now, with the evolution of ice management chemicals, the problem has become increasingly challenging.
The chemistry
Corrosion is a bigger problem than ever before because of changes in the way DOTs now deice the roads and highways. Over the past 15 years, it is estimated that the costs associated with corrosion caused by anti-icing chemicals have increased more than tenfold. “A lot of this is due to the increased use of magnesium chloride (MgCl) and calcium chloride (CaCl) as deicing chemicals, says Chris Stolfe, senior manufacturing engineer at Great Dane Trailers. “Corrosion has always been a problem, but it’s been exacerbated by the use of MgCl and CaCl, which act differently than sodium chloride (NaCl) when they get on the underside of a truck or trailer. They dry out and form crystals that are hydrophilic and will draw moisture from the atmosphere even in low humidity levels. In doing so, they return to a corrosive solution.”
Corrosion is an electrochemical process in which the iron in the steel serves as the anode, the oxygen in the air as the cathode and the aqueous solution as an electrolyte. MgCl and CaCl can literally suck water out of the atmosphere and remain on the surface as a solution, which keeps the corroding chemical cell going.”
Rod Ehrlich, senior vice president and chief technical officer at Wabash National, says that state and local road crews used to salt roads when it snowed. Now they salt if it might snow. As a result, we’re seeing substantially more deicing chemicals being used than we did formerly. MgCl and CaCl have two characteristics that make them more aggressive with regard to corrosion. First, they tend to cling to surfaces far more tenaciously than NaCl. Secondly, they are far more hydrophilic than NaCl.
Ehrlich says, “If we’re able to quickly get any deicing chemical off a metallic surface, it will do little damage. On the other hand, if we can’t get it cleaned off, and continue the exposure of the metal to a salt solution, corrosion will accelerate. NaCl can easily be rinsed off. Unfortunately, the other two commonly used deicing chemicals will not respond to a casual rinse because of the way they cling to the surface and will remain corrosively aggressive because of the water they attract from the atmosphere.”
Changes are unlikely
There is a growing concern about the negative aspects of the use of newer deicing chemicals. Brad Van Riper, senior vice president and chief technology officer at Truck-Lite Co. Inc., reported on comments made at the recent meeting of the Technology and Maintenance Council (TMC). He said that the trucking industry is finding that MgCl and CaCl may be contributing to both health and environmental issues. It appears that cabin filters may not be adequately trapping the dust resulting from these deicing chemicals and ground water salinity in some areas of the country is increasing due to the use of these chemicals on roadways.
Despite these observations it appears that the use of either of these two chemicals will not be discontinued. Travis Hopkey, director of marketing at Phillips Industries said at that same TMC meeting, “Over 38 states are currently using some sort of MgCl or CaCl to de-ice their roads. These new chemicals cost approximately one-third that of salt compounds. MgCl in particular can be applied in anticipation of freezing temperatures making it much easier, effective and safer to spread for municipalities. The economic advantages to state DOTs are significant, so this condition isn’t going away anytime soon.”
Great Dane’s Stolfe agrees, “You’re not going to make those chemicals go away. They’re very popular because they’re cost effective. The only way to deal with corrosion problems is to either use a barrier to keep the corrosive chemical off the metal or to use corrosive resistant materials.”
What to do?
Trailer manufacturers have a number of choices when it comes to protecting their products from corrosion. Wabash National’s Ehrlich says, “There are a number of different ways we protect surfaces from corrosion. The most important strategy is to put a barrier between the corrosive electrolyte and the metal. Many barrier materials are used in the industry and generally will work as long as they prevent ions of the electrolyte from contacting the metallic surface.”
The choice of material depends a great deal on what surface is being protected. In any case, the desire is to avoid coatings that would allow a corrosion cell to develop. On a microscopic scale, many paint formulas actually have fissures that will allow ionic contact with the metal substrate. If that happens, corrosion damage can spread under the coating, which actually protects the corrosive action. The result is worse than not being coated at all.
Ehrlich continues, “We’ve just recently gone over to a more flexible thermoplastic coating that does much better than the harder, brittle coating that we formerly used. That was a polyester, which was subject to corrosive undermining because it was hard. Painting the undercarriage is disastrous! There we need a coating that is very forgiving. That’s the reason we use a soft coating that can easily be repaired if it’s damaged.”
Undercarriage protection
Trailer manufacturers generally use what they refer to as “soft films” to coat undercarriage components. Such films have molecules that are hydrophobic and stick very tenaciously to steel surfaces. They are also self-healing if the injury is small enough. According to Stolfe, Great Dane has taken the next step in anti-corrosion technology in its development and introduction of an optional spray-in-place thermoplastic coating called CorroGuard, which he says provides superior long-term protection from road abrasion and corrosion.
Stolfe says CorroGuard is air tight and water tight, and will not peel, crack, warp, flake or split under even harsh conditions. It is rapid curing and does not require humidity or moisture to cure so it can be applied in cold temperatures and will not bubble in climates of high humidity. CorroGuard remains pliable and withstands prolonged UV exposure. Because it is formulated from solids and does not contain any volatile compounds, it is not carcinogenic, ozone depleting or harmful if inhaled.
It’s not only trailer manufacturers that are concerned with corrosion of their products. Component suppliers are also addressing the problem. Hutchens Industries Inc., for example, recently introduced a new slider, its 9036i. Eugene Robinett, manager of intermodal and international sales at Hutchens, says of the design, “Its cast sidemount hangers have no hidden pockets for moisture to accumulate, making it the most corrosion resistant intermodal suspension/subframe available.”
SAF-HOLLAND also has addressed the problem of corrosion on landing gear with its Black Armour treatment. The product reacts with any metal that oxidizes, causing it to grow a protective layer that the manufacturer says is ten times more impervious to water than a swimming pool coating. Black Armour also has a built-in corrosion package that compresses with heavy impact rather than shattering. When treated products are gouged or scraped, rust is stopped from spreading beyond the point of contact. Black Armour can take the place of a matte finish coat, or if an additional topcoat is required, it can be applied without additional treatment.
Lighting systems
Not much more than a decade ago, lighting systems demanded more frequent attention than any other system on a truck or trailer. Now lighting’s not even in the top ten! That says a lot for the products currently available, but there are still many problems in the field –– many of them avoidable.
Truck-Lite’s Van Riper says, “The most problematic item in lighting systems used to be the filament. That’s been eliminated with LEDs. The second was, and now has moved up a notch, corrosion of connectors. Corrosion can be the new ‘weak link’ in many electrical systems, but premium connectors can avoid corrosion problems.”
When LEDs first came out, everybody loved the idea of eliminating troublesome lamp filaments, but trouble with corrosion in terminals at the interface between the lamp and harness continued. All major lighting system manufacturers have expended great efforts to design-out corrosion problems from their products. Grote, for example, introduced its male pin lighting system that has the terminals on the lamp rather than on the pig tail. The result is an effective O-ring seal upon assembly. Concerning the system, Dominick Grote says, “In many cases, you get a compression fit between the base of the lamp and the surface of the trailer. It makes it very difficult for any road chemicals to make their way into the connection.”
Environmental tests in Grote labs have indicated that there is a significant advantage in using lamps and harnesses manufactured by the same company because of the interface between the two components is so critical. Grote says, “Our data indicated benefits when you use a complete system instead of a piecemeal system where you mix and match components.”
Darry Stuart, president and CEO of DWS Fleet Management Services, says, “Trailers have a very long service life, so there are still thousands on the road without sealed lighting systems and, unfortunately, there are still technicians using test lamps or even cutting wires and using butt connectors.”
But hope is on the horizon. Van Riper says, “I’m seeing good things from fleets regarding probing wires. I know of one fleet that has a policy saying that the presence of an ice pick in a tech’s tool box is grounds for dismissal.”
Maintenance matters
Since breaching a wire’s insulation is a sugar-coated invitation for corrosive road chemicals to attack the copper wire inside, probes of any sort should never be used, but there are other maintenance practices that will help minimize financial losses due to corrosion, some of which have changed in recent times. Grote says, “We used to recommend that you regularly unplug lamps, clean the terminals, regrease them and reassemble them. At the time, that was good maintenance practice. Now, however, we offer connectors that we warrant for 10 years, so we no longer recommend disconnecting the lights.”
Great Dane suggests two simple preventive maintenance steps to help avoid major repairs of a trailer in the long run. Frequent pressure washing with a properly mixed ratio of fresh water and soap, especially in the undercarriage area, helps remove corrosive chemicals used for deicing. Cleaning procedures should include a low to mild pressure application to ensure against lifting fresh/new coatings at abraded areas as well as thorough rinsing. Repair any damaged areas of coatings as soon as possible to prevent spot corrosion that can spread.
Road equipment is simply too expensive to let it rust away without trying to protect it. No, you will never completely defeat corrosion, but you can minimize your share of that $30,000,000,000 loss.
Engineering Efforts
There are a couple of industry efforts currently taking place that promise to improve design efforts of manufacturers in their engineering programs aimed at corrosion control.
At the recent Technology and Maintenance Council (TMC) meeting, Travis Hopkey of Phillips Industry said, “Present testing is not tackling the corrosion problems seen in electrical connectors. The ASTM-117 ‘Salt Fog’ test that many electrical manufacturers rely on does not reflect what actually happens in the real world. The salt fog tests are conducted in a passive environment, with no electrical load and do not use the de-icing compounds currently used by most states.”
To correct that problem, Vern Caron, director of commercial vehicle electronics at ArvinMeritor, is chairing an SAE committee that has written a new environmental test procedure that will replace the current “Salt Fog” test and be far more representative of corrosion expectations of vehicles in service. The new test will be cyclical, include heating cycles and various chemical “cocktails” as well as an abrasion component. The effort has been underway for five years and has resulted in a 25-page TMC Recommended Practice.
The second program is being conducted by a TMC group chaired by Roy Gambrell, director of maintenance at Truck It Inc. This group is currently gathering data from fleet members of all the various TMC Study Groups to determine exactly what components are susceptible to corrosion problems and the costs caused by corrosion. From this they will decide what priorities will be placed on programs aimed at solving these problems.
