DON MILLS, Ont. -Trailer component degradation is a major issue for buyers, but not one that’s necessarily well understood, and for good reason.

While there is consensus on corrosion being all about chemistry, some believe stainless steel is their best protection against corrosion, while others disagree.

“Many people will look at how badly some of the trailer components have corroded and assume it would be worse if they hadn’t used stainless steel. But in actual fact they don’t realize they are encouraging the corrosion by using stainless and damaging adjacent materials,” says Ray Camball, fleet sales manager for Trailmobile Canada. “The aluminum or other alloy gets the blame for the corrosion because it is those parts that corrode. What buyers don’t tend to realize is that they’re damaging the opposing part when they use stainless in their trailer.”

When two dissimilar metals are mixed and salt is added, which is common in Canada, a galvanic reaction occurs, explains Camball. The voltage of the metal will travel one inch away from the connection and the metal with the lower voltage will always sacrifice itself to that with a higher voltage. In trailers the latter is often stainless steel, he says.

Gary Bell, manager for Hautlec Trailers, agrees, at least when it comes to the basic cause of corrosion.

“There is always some corrosion between the two metals, it is the nature of the beast,” Bell says. “The two materials together (aluminum and steel) and once you get some salt in there too, it basically creates a battery.

“Under those conditions it is the aluminum that is more susceptible to breaking down than the steel. If you put stainless steel up against the aluminum it is just as bad or worse because the stainless conducts electricity better than carbon steel so it basically happens faster.”

Corrosion culprit or no, stainless does have its place in a trailer, provided it has a small surface area so that its higher voltage can be diluted by a larger surface area of lower voltage material, Camball says.

Given the fact that aluminum and steel obviously don’t mix, it’s easy to take sides.

Richard Hignett, vice-president of marketing and sales for Glasvan Great Dane blames aluminum for corrosion.

“The bigger culprit is the aluminum. You can put carbon steel and stainless steel together and get virtually no corrosion but with the aluminum against either metal, corrosion will occur. So it is the aluminum that is the guilty party,” Hignett says.

Competing theories on the benefits of stainless versus aluminum put forth by trailer experts are also reflected in current trailer buying trends.

Many say that the use of stainless is purely cosmetic and used to create a certain polished image.

“Stainless is very appealing to the eye, but I think it is strictly cosmetic,” says Angelo Ciciretto, president of Markham Equipment.

Buyers tend to prefer stainless but do not want to spend the extra money just for the way it looks, he says.

“Stainless may appear to be longer lasting but it is a heavier material and if it does get a dent or a dimple, it is much more costly and more difficult to fix,” says Ciciretto.

And if a stainless trailer is dented it would defeat the purpose of acquiring a stainless fleet for the image of pristine, shiny, clean trailers, he adds.

The main motivation for going with stainless, says Camball, is to keep the trailers looking newer longer.

“Rust spots on the trailer can send a bad message to customers on the highways or even alert inspectors to pull you over,” he says.

A driver could easily spend an extra $1,000 by adding stainless components to the trailer but the real expense is incurred later down the road in maintenance costs or resale value, Camball adds.

“But drivers should be careful that buying into stainless doesn’t come back to bite them later down the road,” he says.

Craig Sterling, vice-president of sales for Wabash Trailers, agrees.

“Stainless steel is a softer metal and I’m concerned that it doesn’t tend to uphold in the abusive environment that a dry freight trailer operates in the same way a carbon steel assembly does,” Sterling says.

He says he warns customers interested in purchasing a stainless product.

“I always tell customers that if they want that type of material and work in a heavy-duty environment, they may see premature fatigue in areas that they may not expect to see it.”

While there’s little the trailer manufacturer can do if a trailer is not spec’d properly for its application, there are ways to fight corrosion. Trailmobile has included zinc galvonizing as standard material in manufacturing its trailers because it offers the customer the best value, Camball says. Zinc is a low voltage material and a thick coating of sacrificial zinc is the best way to protect the joints of the trailer.

“The zinc works best to protect the aluminum from corroding and it will sacrifice itself over the years but with a good thick zinc coating on the carbon steel, there will be enough for the life of the trailer,” he says.

That is unless acid brighteners are used in the painting process or in the wash that manufacturers use on the metals, which strips the zinc at a faster rate than normal atmospheric conditions do, Cambell points out.

Hignett says another way manufacturers are dealing with corrosion is by installing a Mylar tape between the connecting metals in the joints of the trailer to isolate the metals.

That’s what they do at Haultec, says Bell.

“Because there is always some corrosion between the two metals (it is the nature of the beast) we paint the material before they are put together and we also use a Mylar tape to break up the connection between them,” Bell says.

Another option is using galvanized instead of stainless, points out Roger Gendron, vice-president of sales for Canam Manac North America.

“For the last thee, four or five years even, what we have been seeing is galvanized rear door frames, which do not rust at all and are way less expensive. They do the job as well as stainless steel and galvanized steel is a stronger metal.”

Optimal conditions for rusting and corrosion are found in moist environments with temperatures just above freezing and containing road salt, Camball says.

Conditions such as these make corrosion a distinct problem for drivers travelling through what is known as the rust belt – essentially the area surrounding lower Ontario, western Quebec, western New York, Michigan, Ohio and areas around Lake Erie and Lake Ontario. Truckers who operate mainly in this region should take a good look at the construction of their trailers and research the potential dissimilar metal reactions to which the materials in the trailer may be subject.