More painless than stainless

WHEN Bonnell Industries national sales manager Cherie Bonnell began investigating galvanization four years ago, it was largely a result of conversations with a friend, Pat Fordham, director of operations for AAA Galvanizing a mile down the road in Dixon, Illinois.

Bonnell, whose company manufactures and distributes snow plows, under-tailgate spreaders, V-box spreaders, hitches, and other products, wondered how that equipment, if galvanized, would withstand heavy contact with calcium chloride and other solutions.

Fordham told her, “Well, that's what galvanization was designed for — to withstand those elements, as well as the weather.”

One of Bonnell's customers, Cherry Valley Public Works, had a spreader that was originally built in 1993 that it wanted sand-blasted and painted.

“Why don't we sand-blast and galvanize it?” Bonnell asked.

So Bonnell did. And today, she says, Cherry Valley Public Works claims it looks the same as it did when Bonnell delivered it in 2004 — brand new.

Bonnell had no idea that market forces would turn galvanization — and a process called hot-dipped galvanizing, which coats steel with a thin zinc layer by passing it through a molten bath at high temperatures — into an increasingly acceptable and popular option.

Manufacturers have developed a higher sense of urgency to explore galvanization because the price of stainless steel has skyrocketed. Grade 304 stainless, for example, more than doubled in price between January 2006 and January 2007, and was over $3 a pound in late April.

Bonnell said her suppliers told her it was due primarily to the increased cost of nickel, which makes up about 10% of Grade 304 stainless. The price of nickel at the end of the first quarter this year was three times that of the price a year ago. Bonnell says she has been told a 52% rise is expected for the calendar year.

She says she also has been told to expect another stainless-steel price hike in June.

In April, she calculated that a customer could buy two of Bonnell's 10' V-box galvanized spreaders made out of A36 carbon steel for almost the cost of one Grade 304 stainless-steel unit.

A galvanized under-tailgate spreader cost 30% less than a 304 stainless-steel spreader and only 15% more than a painted spreader. A galvanized V-box spreader cost 45% less than a 304 stainless-steel spreader and only 20% more than a painted unit.

“There are alternative situations out there,” Bonnell says. “You don't have to go with stainless steel, because the price of stainless steel is just ridiculous. We're just trying to get people to think out of the box.

“We're gearing our sales to townships within a 100-mile radius of Dixon. They're the ones we need to sell to. These townships in northern Illinois don't have a lot of money. So for somebody to buy a stainless-steel spreader when they can buy two carbon-steel galvanized units doesn't make a lot of sense.”

When Bonnell originally started working with galvanized products, she faced skepticism because people did not understand the process of hot-dipped galvanizing.

“A concern is that people think you can't paint over the galvanized finish to get rid of that dull finish,” she says. “But you can. There's a process that you have to go through in order to paint over galvanized so the paint adheres to the galvanized steel. Some people think the galvanized product doesn't have the nice finished look to it. It does look somewhat gray after it has been exposed to the weather. But personally, when I look at a stainless steel spreader, it's not the nice shiny stainless steel you might see in restaurant equipment. I think the galvanized product looks just as good as stainless steel product.”

Bonnell believes that her galvanized products were not a hugely popular item four years ago because stainless-steel units were still very affordable.

“It was more cost effective back then to go with stainless steel,” she says. “That's why I believe it didn't take off. In everybody's mind, stainless steel was better, and it wasn't so outrageously expensive to go with at the time. I tried to present the concept as an alternative to our dealership network across that US, but it wasn't something they were used to. But I've done my homework and all the research. I've been collecting the information and I'm sold on it.

“Recently, I've been talking with our customers and our dealer network, and everybody is interested in the concept. How much it grows is something I can't answer.”

There are advantages beyond the huge cost savings. Fordham says galvanized products provide the aging properties of stainless steel, without producing rust or requiring any maintenance as far as painting or touching up. The zinc surface offers a life that is actually five times longer than painted steel.

Says Cherry Valley director of public works Joe Caveny about the 14-year-old spreader that was sandblasted and galvanized in 2004, “It looks like new. We maintain it simply by washing it with water after each use. If we buy another tailgate spreader, it will be galvanized.”

Harlem Township road commissioner Mark Bratley says his galvanized spreader is much easier to clean than painted units.

“The salt sticks to the paint and that is hard to clean,” he says. “We steam-pressure wash to maintain our galvanized units, and that works great. We will not buy another painted carbon-steel unit. We will definitely purchase more galvanized spreaders.”

Those who are more into aesthetics can choose to paint their galvanized units.

“Everybody wants a fancy trailer and colors, and galvanized is not that,” Fordham says. “But painting over galvanized isn't that difficult. A lot of Bonnell products go out as is, which is fine, because anytime you paint, you still have to keep upkeep on it — and that's not what the niche is for hot-dipped galvanized.

“But it's very easy to paint. So what you're gaining then is a great base product that can't age. So if you see the paint chip, its not going to rust right away because galvanized is good for 20 years. It gives you the ability to touch up with paint and not lose any base metal from rust. So I'd consider a painted galvanized unit to be a lifetime product. You would never replace it.”

In it for 18 years

Sauber Manufacturing Company of Virgil, Illinois, also sees the benefits.

Sauber makes trailers only for the utility industry, and basically introduced galvanized trailers to that industry 18 years ago.

Sauber is a developer, manufacturer, and distributor of products for electric, telecommunications, municipal, contractor, and gas utilities. Its products include pole, reel, cargo, turret, self-loading, flatbed, substation recovery, and oil filtration trailers and accessories.

Marketing manager Mike Blaser says there was initial hesitation 18 years ago because of aesthetics, but a lot of customers began to view trailers as “more of a tool than a vehicle.”

He says that a galvanized trailer has to begin with the engineering process — they are specifically engineered to be galvanized.

“When it is dropped into the molten zinc, the zinc goes both inside and outside the tube,” he says. “So you have to provide proper drainage for the holes for the liquid to penetrate both sides of the metal. In tube-frame construction, most of the damage of corrosion begins inside. It's the most dangerous form because you can't see it occurring. The galvanized process eliminates that risk.”

The durability of galvanized trailers is critical in the utility industry. He says linemen are rough on the trailers in the process of loading poles or equipment.

“The first thing they do is slide poles across the I-beams and ratchet them down,” he says. “If it's a painted surface, you've scratched the paint and begun the rusting process.”

Sauber will paint its trailers if the customer requests, but the majority of the orders deal with a standardized surface of galvanized steel that is applied at AAA Galvanizing's plants in Dixon and Joliet.

“Our commitment is putting out a product that is maintenance-free,” he says. “The majority of our trailers are stored in a parking lot, exposed to the elements.”

The process

Bonnell and Sauber take their finished products by trailer to AAA Galvanizing, where the truck is weighed, unloaded, and then weighed again so that a product weight can be determined. (AAA Galvanizing charges by the pound for the hot-dipped galvanizing process.)

There are four stages to the process:

  • Caustic soda

    The steel is immersed in caustic soda, or sodium hydroxide, for five minutes at 150 degrees F. This removes soil, oil grease, and soluble paints so the surface of the steel is cleaner and more reactive.

  • Acid

    The steel is immersed in a hydrochloric acid tank to remove surface rust, mill scale, and similar deposits. Then it is rinsed and drip-dried, leaving the surface of the steel as pure metallic and ready to be pre-fluxed. “This stage lasts for 1-2 hours, depending on thickness of scale,” Fordham says. “Hot-rolled steel has more scale than cold- rolled, and trailers usually have a bit of both. So it could be up to two hours. You want to get the scale off the steel and get white-blasted or pure metal. It's almost shiny-looking silver when it's clean.”

  • Pre-Flux

    The steel is immersed in a pre-flux solution of zinc ammonium chloride for five minutes at 145 degrees F. This prevents oxidation and keeps the surface protected prior to dipping in molten zinc. “We have a dryer that pre-heats the steel and flux at 175 degrees F, and that's to dry the flux to the surface, make better quality, and preheat the steel. That helps get the steel into the kettle faster, which is important for trailers to prevent warping.”

  • Molten Zinc

    The steel is immersed in a molten zinc kettle (51' long by 7' wide by 10' deep) at 835 degrees F. (Trailers that are over 7' wide are turned on their side and hung by chains or wires.) The base metal is heated to the same temperature as the molten zinc during this process to facilitate the metallurgical bonding necessary to join the two surfaces. Because the base metal is “dipped”, the entire unit is flooded with liquid zinc. This allows for the inside of tube frames, tight corners, and virtually all surfaces to be galvanized. In contrast, painted or metalized surfaces can only cover areas where the spray can reach, and depend heavily on the skill of the operator doing the application.

After the fourth stage, the unit is pulled out of the kettle and sent to acute quality control for the cleaning process, which removes any excess drips and runs and preps it to be shipped back to the customer for final assembly and the installation of wheels, reflectors taillights, hitches, etc.

Galvanized components

Vanguard National Trailer Corporation has figured out a way to effectively incorporate galvanized components on its dry-freight trailers.

Vanguard, formed from the assets of HPA Monon, produced its first trailer in the spring of 2004 and by the summer had produced its first trailer with galvanized components.

Vanguard's plant in Monon, Indiana, does primarily assembly, with very little in-house fabrication. All of its fabricated parts come from the Shanghai, China, plant of its sister company, China International Marine Containers.

All of Vanguard's steel fabricated assemblies on its dry-freight trailers are galvanized: the rear frame, rear impact guard, landing gear bracing, the structural members between the coupler and landing gear, and the apron of the coupler.

“Because we just got into the market in 2004, we wanted to listen to what people are saying,” director of engineering Mark Roush says. “The hot topic is corrosion resistance. So we figured we needed to do what they were asking.”

In the future, Vanguard anticipates that it will galvanize the entire understructure.

“The more the better,” Roush says. “There are some coatings that people are starting to tout as being great at corrosion resistance. But what you get with hot-dipped galvanizing is that the complete part or assembly is dipped. That means the interior and exterior are dipped. If you're painting, you haven't done anything for the inside. I would imagine that high-tension towers and metal light poles wouldn't be galvanized if there were a paint or another coating that was far superior.”

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