Dealing with road salt and corrosion is nothing new to Chuck Diehl, fleet manager for Smith's Dairy in Orrville, Ohio. Considering the company's location in the northeast part of the state, "It's always been something that's part of our environment," he says, especially with the 10- to 12-year life cycle they expect out of their equipment.

"But in the last three years, now that the state of Ohio is using the new liquid de-icers, we have definitely seen this accelerated," he says. "It's been amazing to watch to see how it's attacking anything that's metal. If it's anything that's mild steel and it's not properly prepared and coated or treated, you can kiss it goodbye in just a couple of years."

Frame rails, crossmembers, suspension components, air tanks, fuel tanks, battery boxes, brackets, brake shoes, electrical systems, air-conditioning condensers, radiators, metal coolant tubing, steel wheels, inside the floor of the cab - even refrigeration units aren't safe from the corrosion monster, Diehl says. "It has really changed our thinking and how we approach treating all those metal surfaces."

Diehl is not alone. The problem has become so pervasive, the Technology and Maintenance Council of the American Trucking Associations set up a Corrosion Control Action Committee, which had its first meeting during TMC's Fall Meeting in Nashville in September. The committee's goal is to coordinate with TMC's many study groups to develop recommended practices for equipment manufacturers and fleets to prevent corrosion problems.

TMC has calculated some estimates of what corrosion is costing the industry, based on a 2004 survey of fleets and available statistics on the number of commercial vehicles.

If you assume that during a four-year period, each of the 2.35 million Class 6-8 commercial vehicles in the country has to have its wiring, two sets of brake shoes and drums, lights, a fuel tank, a radiator and a mirror bracket replaced, you're looking at $2.4 billion to $4 billion a year. That doesn't even take into account trailer corrosion costs, the costs of frequent washings, or the cost of road calls - and 63 percent of the fleets responding to the TMC survey said they had experienced road calls due to corrosion.

The Chemistry Of Corrosion


At issue are the new liquid de-icers that have become a common weapon in highway agencies' battle against snow and ice - magnesium chloride and calcium chloride. When sprayed on pavement in advance of a coming storm, these chemicals can prevent ice from forming on the roadways, making snow removal easier and in some cases keeping the pavement clear.

"This stuff costs about a third less than those big mounds of salt you see, and it's safe to put on because you can put it down before the snow hits, and it really doesn't evaporate," says Travis Hopkey, director of marketing at Phillips Industries. "So it sticks around and melts the snow - but it also turns into a fine mist and gets everywhere. Any exposed material or exposed connection - the whole truck and trailer gets coated in this fine mist, and it seeps into tiny little crevices and cracks and starts to work its magic."

Some of the properties that make these chemicals so good at keeping roads clear are the same characteristics that make them so destructive.

For one thing, as Hopkey notes, calcium and magnesium chloride are highly soluble in water, so they produce a finer mist of spray under the vehicle than old-fashioned rock salt does.

Mac Whittemore, regional manager with ArvinMeritor, explained the situation at TMC's corrosion committee presentation. "Because this spray is finer, it starts penetrating into areas where you wouldn't necessarily think it can get to - underneath the paint, inside the brakes."

Both these chemicals are hygroscopic, which means they will absorb moisture from any source. In fact, they are also commonly used as desiccants, and for dust control on rural roadways. If you put a chunk of dry magnesium or calcium chloride on a table in a laboratory environment and leave it overnight, when you come back, it will have a puddle of water around it that it has absorbed from the air.

This means that even when the weather and your equipment are dry, the chemicals continue to attract moisture. They easily mix with the water they attract and then seep into the tiniest cracks. Recent reports even have found corrosion seeping into the air brake system.

It's unlikely that highway departments will stop using something that has proven to be such an effective lifesaver.

However, there have been some concerns from other corners besides the trucking industry. Some studies seem to show these de-icing salts cause concrete to deteriorate more rapidly, and electrical utilities have reported corrosion of power poles as well as electrical shorts.

There are corrosion inhibitors and other buffers that can be added to these chemicals, but costs and problems with handling have meant slow adoption. Washington and Idaho have pioneered programs to limit corrosion through strict specification on the corrosiveness of de-icing chemicals, and other states and provinces are exploring its use, according to Morris Chemicals, which markets calcium chloride.

What Equipment Manufacturers Are Doing


Manufacturers of trucks, trailers and various components have been working to develop more corrosion-resistant products. Some examples from this year alone:

• Isuzu's new N-Series for 2008 touts greater corrosion protection, from the galvanized steel panels to the electro deposit paint primer and high-quality enamel paint topcoat.

• Great Dane Trailers introduced a package of corrosion prevention solutions featuring CorroGuard, a spray-in-place thermoplastic elastomer coating applied to suspensions and support gear.

• When Freightliner introduced the Cascadia, it touted corrosion protection for fasteners.

• ArvinMeritor's RideSentry trailer suspension with a new PinLoc slider locking mechanism featured an e-coat protected slider.

• Hendrickson's latest InTraax trailer suspension uses patented Tri-Functional III Bushings with phosphate-coated inner metal for corrosion protection.

At TMC, Whittemore talked about the research ArvinMeritor has been doing to try to develop corrosion-resistant brakes. "Rust jacking" on brakes was one of the first clues the trucking industry had that there was a corrosion problem. This happens when corrosion develops between the brake shoe table and the brake lining. Because rust has a higher volume than the originating mass of iron, its buildup can force adjacent parts apart. This causes the lining to lift and crack. On a rust-jacked brake shoe, rivets will still be holding part of the lining to the shoe, but in between the rivets, it's cracked.

ArvinMeritor has been testing paints, e-coatings, ceramics, pre-treatments, and adhesives that seal the area between the brake shoe table and the lining. A full-time program manager heads its rust jacking prevention efforts. The most promising approach, Whittemore said, is a process of applying an adhesive membrane between a new shoe table and the lining material. This heat-activated material would melt under the application of the brakes in the real world, sealing the lining to the brake shoe. The problem is, once the adhesive membrane has set up, that brake shoe cannot be re-lined. They also don't know at this point what kind of a price premium this technology would demand.

One important step to help manufacturers develop equipment and treatments that will better resist corrosion is a laboratory test that can accurately simulate the effects of these de-icers. In the past, a standard from the testing-standards organization ASTM, B117, commonly called the salt spray test, has been the industry standard for testing corrosion resistance. But this test has not been very accurate at predicting real-world performance with today's de-icers.

"We're finding out that extending the time in the salt spray chambers was not correlating with actual field test data," said Brad Van Riper, senior vice president and chief technology officer for Truck-Lite, in a presentation to the TMC corrosion committee. "Five years ago we were doing 240 hours (in the salt spray chamber) at Truck-Lite. We moved to 1,000 hours, but 1,000 hours of salt spray are not satisfying the customer and they're not correlating well with the field experience." In other words, components may be lasting five times as long in the salt spray chamber, but they're not lasting that much longer in the real world.

"We've got to have a way to measure ourselves to improve," Van Riper said. "Having a good test in place seems like the first step."

Van Riper is on the corrosion task force of the Society of Automotive Engineers that has been working for several years to develop a more accurate test, known as SAE J2721. In addition to actually using the new de-icers rather than just traditional road salt, one of the key differences in this test will be using a cycle of conditions - for instance, a body exterior might go through cycles featuring a wet soak, a salt application, then a dry soak.

"On the (current) salt spray test, we're only seeing a wet period, and we know that wetting and drying of the corrosive materials can contribute to accelerated corrosion," Van Riper explained.

A test for chassis corrosion resistance would include gravel bombardment and a slurry grit as part of the cycle. "The point is, we're exposing the components to much different corrosion qualifying tests than has ever been done before."

The proposed standards would provide criteria for whether the component passes the test, including standards for cosmetic corrosion, functional corrosion, and structural corrosion, including photos to help determine what level of corrosion is present on tested components .

Fleet Strategies

There are an increasing number of options you can spec when buying a truck to help prevent corrosion. Only you can make the determination on whether they provide an effective return on investment in your operation.

The electrical system is one area that is particularly vulnerable, and with increasing use of electronics on vehicles, it's more critical than ever to keep corrosion at bay. As the electrical system is powered and unpowered, and wires heat up, they expand. When they contract, they draw in the air around them - and contaminants and moisture.

Phillips Industries spotted a corrosion problem in electrical components soon after the dawn of the new millennium. "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," Hopkey says. "Fleets should look for products that are specifically built to resist corrosion. We've got everything from plugs and sockets to gladhands."

And corrosion protection is not necessarily expensive. Little details can make a big difference. For instance, Hopkey says, the seven-way connector's design inherently lets in moisture. Phillips now offers a foam socket insert that slides over the pins in the seven-way connector socket into the base to seal out moisture.

Any time a tractor or trailer is repaired, use a heat shrink terminal that seals out moisture. The old nylon and PVC terminals are unsealed, easily allowing contaminants inside.

When it comes to maintenance, washing vehicles to try to keep the chemicals off the metal is important. There is no clear answer to the question of what washing strategies are best. Pressure washing may only push the chemical mixture further into tiny cracks and crevices. In addition, the new chlorides tend to stick to surfaces more than traditional road salt, and may need physical action to get them off rather than just spraying them with wash water. Keep in mind that more cleaning liquid is not necessarily better - in some cases, an over-concentration of washing compound may actually attack some of the plastics that are there to provide corrosion resistance.

A new area where fleets are reporting corrosion, according to several people at the TMC fall meeting, is the air system - the control ports of air brake valves are developing corrosion.

"This stuff is migrating deeper into the vehicle than we've ever seen before," Whittemore said. "It's getting into the air systems. That corrosive material can get inside the lines, inside the tanks. The inside of a valve fitting isn't expected to be coated with an anti-corrosion coating, at least not yet." That means it's more critical than ever to maintain the air driers and keep water drained from the system.

Hopkey recommends using gladhand seals with dust flaps, which keep contaminants out of the system when the trailer is untethered. Otherwise, it's very easy for rainwater to become contaminated with the chlorides on the trailer surfaces and creep into the air system.

At Smith's Dairy, Diehl says, they have stopped buying used equipment that has been operated north of the Mason-Dixon line. They recently bought some three-year-old tractors from a major leasing company, but found so much rust and corrosion on the frames that they decided to take them down to the bare frame rails and re-paint - something they normally do about midway through their equipment's 10- to 12-year life cycle.

"The rules of the game have changed," Diehl says. "The bar has been raised for us and how we're going to face this corrosion and rust that we're encountering."

About the author
Deborah Lockridge

Deborah Lockridge

Editor and Associate Publisher

Reporting on trucking since 1990, Deborah is known for her award-winning magazine editorials and in-depth features on diverse issues, from the driver shortage to maintenance to rapidly changing technology.

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