Killer Chemicals
Chemicals used to de-ice roads are still wreaking havoc with critical truck components. Here's what you can do to protect vehicles from corrosion.
Deborah Lockridge
Senior Editor
A 3-year-old wheel from an Iowa DOT snowplow. A 3-year-old muffler inlet elbow. A 4-year-old air spring base. A 15-year-old trailer pickup-up plate. Seven-year-old trailer crossmembers. A 4-year-old fuel tank. Air tanks. Brake linings. All coated with rust and corrosion, some nearly falling apart.
This was what fleet maintenance managers saw at the February annual meeting of the Technology and Maintenance Council of the American Trucking Assns., during a panel discussion on corrosion prevention.
It's been about five years since fleet managers started comparing notes and realized that new de-icers seemed to be causing never-before-seen corrosion problems. Since then, we've learned that, despite the trucking industry's protests, these chemicals are not likely to go away. We've also learned some of the reasons these chemicals are so aggressive. And the industry is developing new technology and techniques to help prevent corrosion.
Ordinary salt - sodium chloride - has been used to de-ice winter roads since the late 1930s. In the 1990s, road departments discovered new chemicals - magnesium chloride and calcium chloride - that could be sprayed on roads before a storm and lowered the freezing point of water, keeping snow from sticking and ice from forming.
Unfortunately, after several years of having their trucks exposed to these chemicals, truckers realized that there was another big difference: aggressive corrosion of electrical wiring, truck frames, suspension parts, brakes and more.
Despite the trucking industry's efforts to convince state DOTs that these chemicals are harmful, it looks like magnesium chloride and calcium chloride are here to stay.
"There's definitely a higher demand by the public to have the roads cleared quicker, to have them dry faster," says David Alexander, project manager for the Winter Roads Management Program at the University of Idaho, sponsored by the ATA.
"The public doesn't really want to put the chains on anymore. They don't want to slow down for ice. There's a lot of pressure on the state departments of transportation to use these chemicals."
The makers of these salts are working to add corrosion inhibitors to to their product, but so far they seem to be limited in their effects.
"There's going to be corrosion, and there has to be a certain level of compromise," Alexander says. "I don't think it's reasonable to expect 25 years out of a vehicle without any corrosion damage, but where's the line? What's a reasonable lifetime for the parts, and who's going to make that decision?"
When The Holland Group started looking into corrosion in 1991, it wanted to find out what the industry was looking for in terms of performance. "We really found there's not a real strong industry consensus about what they want. They just know there's a problem," says Steve Dupay, director of research and development.
TMC's Future Truck project has attempted to come up with some industry standards to guide designers of new trucks. Its "corrosion abatement position paper" states that "a user should not need to replace a component over the vehicle's useful life, or the useful life of that component, due to corrosion. This includes Ôsurface corrosion.' Additionally, the user shall not perform any maintenance (other than normal periodic washing) to prevent corrosion."
The paper then goes on to say that users would expect corrosion protection to last eight years on a heavy-duty truck or tractor, 16 years on a trailer or medium-duty truck body, and 10 years on a light- or medium-duty truck. It also says that corrosion protection for add-on components, such as liftgates, spare tire holders, reefers and toolboxes, should last as long as the vehicle to which they're attached.
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Why are these new chemicals so much worse than salt? For starters, they're applied before any snow comes down, so vehicles are more likely to be exposed to the chemicals.
Secondly, both magnesium chloride and calcium chloride are "hygroscopic," which means they attract moisture from the air. They do this at very low humidity levels - 40% or even lower. If you get regular road salt on your vehicle, once it dries, it will generally not start corroding until it is wetted, say by more snow or light rain. Because these new chemicals will pull water out of even relatively dry air, they keep on doing their damage in all kinds of weather.
"If you don't get your truck thoroughly cleaned, even if you're driving in the summer in a hot humid town like Tampa, those chemicals will activate, so you truck will corrode all year round," says Greg Kinsey, engineering manager for Phillips Industries.
Adding to the problem is the molecule size of these salts - they're about half the size of standard salt.
"Those little molecules can fit into tighter cracks," Kinsey says. When the salts are liquefied, "they can cruise right under the heads of rivets, can go more places and get deeper into cracks than standard road salt. No one's invented a scrub brush that will go under the heads of rivets."
This property means that the corrosive material also works its way into any chips or cracks in the paint or coating, and can worm its way under the paint, causing corrosion you can't even see.
Some of the early research from the Winter Roads Program also seems to indicate there may be a compounding effect of these different chemicals. This is particularly relevant to long-haul truckers who travel through several states, collecting a mixture of regular road salt, magnesium chloride and calcium chloride on their vehicles. One of the problems, Alexander believes, is that the hygroscopic properties of the newer chemicals also help keep the regular road salt wet, carrying it into cracks and crevices it wouldn't reach on its own.
Even worse, these new chemicals have a higher surface tension, meaning they're harder to clean off.
"I've come across trucking companies that wash their trucks weekly and they still have problems," Alexander says, "So it's not simply washing it. It needs to be a pretty effective wash. Right now I'm not sure what the best way to do that is, but we hope to get more information as we go along."
Some truck makers have tweaked designs to try to make it easier to get at corrosion-prone parts for cleaning. At International, add-on parts like chassis skirts, for instance, are easier to remove so you can get in to clean the chassis.
Attacking Electrical Systems
One of the first areas where fleets started noticing serious corrosion problems was in the electrical system.
"We were starting to see more returns, and they were really nasty returns, stuff we'd never seen before, and failing a lot faster than ever before," says Travis Hopkey, director of marketing at Phillips Industries.
One of the weak points of a tractor-trailer is the seven-way connection. Because of the design of standard seven-way connector plugs, water can get in fairly easily.
Especially vulnerable is the tractor side of the connection, which is rarely unplugged and gets bombarded with spray from the drive tires. "Because the trailer is plugged and unplugged, opened and closed, seldom do you have problems on the trailer side," says Phillips' Kinsey. "People tend to plug the plug into the tractor side and leave it, and water can collect up in there."
Once moisture penetrates, the copper wire sucks it up like a dry sponge, several feet into the coil assembly. Even if you replace the head, the damage has already been done inside the coil. It adds to the resistance and decreases the voltage you're getting out the back. Some operators may not even know there's a problem until they get a citation for malfunctioning trailer lights.
Phillips' Quick Connect Plug, or QCP, addresses this problem. It features molded ends with replaceable cartridges. Not only are the molded ends, with their solid brass pins, more resistant to corrosion, they are also easily replaced when you do have corrosion.
"Inevitably, everything is going to corrode, anytime you have copper and electricity together," says Hopkey. "What you can do is try to push it off as long as possible." Instead of the typical 20 to 30 minutes it takes to replace the plug on a standard seven-way connector, Hopkey says, the QCP cartridge can be replaced in less than a minute.
No matter what type of seven-pin connector you spec, regular inspection and cleaning can help ward off corrosion problems. Wash the plug with water and a stainless steel brush, then regrease.
Seven-pin connectors aren't the only electrical components subject to corrosion. "Make sure electrical connectors are sealed against the environment," Alexander says. "Just because it looks like it's sealed, because it has a plastic connector, doesn't necessarily mean it's going to keep water out. Make sure you know whether they're designed to be water tight."
Phillips also has other products that it says resist corrosion better than standard industry versions, including its Sta-Dry sockets and QCS 2 harnesses.
Coatings Key
Coatings - paint, electrocoating, powder coating and more - can be significant in the prevention of corrosion.
Electrocoating, also called e-coat, uses a voltage potential or charge to deposit paint onto a part or assembled product as it is dipped into a paint bath. Then the parts are baked to cure the paint. It can be used as a primer coat, top coat, or both, and is used to coat car and truck bodies.
In powder coating, finely ground particles of pigment and resin are electrostatically charged and sprayed onto the products to be coated. The parts to be coated are electrically grounded, so that the charged particles adhere to them until melted and fused into a solid coating in a curing oven. OEMs are using powder-coating on many products. Makers of steel wheels have been using powder coating for several years, and International Marketing Inc. recently began offering powder coating as part of its wheel refinishing offerings.
One chemical that has traditionally been used in corrosion-resistant coatings is hexavalent chromium - the cancer-causing chemical compound made famous in the movie "Erin Brokovich." Because of the health risks to workers, the use of hexavalent chromium is heavily regulated. The European Union will soon prohibit its use on vehicles. This has led to the development of a variety of new types of coatings.
For instance, Elisha Technologies, a division of Orsheln, offers a process called Electrolytic Mineral Coat, or EMC. This process creates a silicate mineral surface on metals instead of chromates.
"From all the information I've gathered, these [newer] coatings are just as effective as the old hex-chromates," says Winter Roads' Alexander. However, he notes, new coating technologies tend to be a pretty exact science. They require special cleaning of the part before coating, the right concentration of chemicals, the right voltage or static charge, etc. "If the concentrations aren't high enough or the part isn't submerged quite long enough, the chemical isn't going to get to all the cracks and crevices of the part, and it won't be effectively coated. Make sure the coating manufacturer is following the proper procedures and protocols and they have good quality control in place."
Some in the industry contend that passenger car bodies are painted and sealed with better coating technology than those on many heavy-duty trucks.
International Truck & Engine says it uses the same process as the automotive industry - an e-coat, a base coat of paint, then a urethane clear coat.
"For the most part, we don't see [corrosion] issues with parts that are coated correctly and have not been damaged," says Ed Melching, director of International's Heavy Product Center. "If you have scratches or dings or anyplace the bare metal is exposed, you potentially are going to have some issues."
One of the key factors in the e-coat process, Melching notes, is that the cab is entirely submerged in the paint, and the electric charge encourages the paint to get into every nook and cranny. "You want to not only cover the outside of the cab shell, you also want to get into all the crevices, because if water gets in there, that's where it will corrode, from the inside out."
International also cuts all holes in the cab, even for special orders, before the coating process, not after.
With the launch of the High Performance Vehicle (International 4000, 7000 and 8000 Series), International began powder coating key chassis components, such as the fuel tank, battery box, air tanks, bumper, wheels and cab suspension. Powder coating offers much higher impact resistance, to avoid scratches that can act as entry points for corrosion.
Truck cabs are typically not where the worst corrosion problems lie. Many manufacturers of other components and add-on equipment are adopting more corrosion-resistant coating technology.
For instance, Waltco Truck Equipment Co. is using a powder-coat for its liftgate products that it says can add two years of life in the northern tier states. Liftgates are in one of the worst environments, on the rear of the truck, where they get not only the salt spray, but also stones thrown up that chip the finish.
"They're in the worst possible environment," says Dave Hammes, senior manager of sales and marketing.
Hammes explains that surface preparation is key to the powder coat process. The metal is prepared through shot blasting, then the components are powder coated in a system that electrically charges the paint and the surface to be painted so they flow together. The paint is electrically attracted to every nook and cranny. Then the sprayed material is baked at 400 degrees for an hour.
"Anyone who is not shot blasting is trying to get rid of rust and scale and impurities on the surface with chemicals, with a rag, and that doesn't work," he says.
The Holland Group also has products that are in a very exposed, harsh environment - fifth wheels, landing gear, trailer slider frames, and suspension components that are hit by stones, ice, dirt and, of course, salts. So in 2001, the company started looking for a new coating process.
"We found out there were two things that were causing our current and other competitive processes to corrode," explains Steve Dupay, director of research and development. "One, when you get those chips, the metal is exposed, and the rust starts there and spreads. The other one, which was sort of new to us, was the realization that most coatings allow water to pass through them, and that also causes corrosion."
After looking at a number of different coating technologies, Holland settled on one it felt would best address the shortcomings of its old paint system. The product, which Holland is calling Black Armour, reacts with the metal and mechanically bonds to that surface, then "grows" a protective skin on the steel.
"The result is an impermeable protective skin that's been 'grown' onto the steel," Dupay explains. "It's not adhered; it's mechanically bonded to the steel, so it won't peel off. It's integral to the surface of the steel, so corrosion can't run under the coating." It's also resistant to chips and scratches. Holland plans to have it on all its products by the end of next year.
"The main point I'd challenge the fleets with is, start asking questions of your suppliers - what can you do for me to improve corrosion resistance?" Dupay says. "Certainly manufacturers want to provide an excellent product, but the drive for improved corrosion protection being designed into the product, that request should be driven by the end customer to their suppliers."
As we've seen, there are a number of companies, associations and researchers looking into the issue of corrosion. The problem is, they need to talk to one another more.
"Probably the biggest issue we've come across is there's a lot of information out there, and not a lot of research that ties everything together," says Alexander. "Corrosion is a pretty complex process. It involves many factors which make it very difficult to just come up with a simple solution to prevent it."
Killer Chemicals continued...
