Innovators: Building better tankers

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Praxair aggressively pursued rollover and capacity solutions by redesigning its tanker subframes and creating a portable storage tank that can be hauled to a customer’s jobsite and filled on location.

It’s not like Praxair has a major problem with rollovers. In fact, the company, which operates more than 600 Class 8 tractors and 750 trailers in its North American private fleet, averages only a couple of such incidents every year. In all, it’s a solid record for any large carrier.

“We’ve had years where we’ve had zero rollovers and years where we’ve had four or five,” says John Mitchell, national manager of distribution for the Fortune 300 company that supplies atmospheric and specialty gases to industries around the world.

But when you’re handling potentially dangerous cargo like oxygen, nitrogen, argon, helium, acetylene and hydrogen, one rollover is one too many.

“We typically have one of the better statistics in trucking,” Mitchell says. “But safety has to be our first priority.”

That’s why the Danbury, Conn.-based company is aggressively pursuing both high- and low-tech approaches for reducing the number of its rollovers to zero – every year.

In addition to adopting a high-tech electronic rollover warning system that interacts with drivers, the company also took a hard look at its equipment – standard atmospheric and specialty gas tanker trailers – and asked if it could make them less prone to rollovers. What it found was a low-tech solution to an inherent problem with tankers: Lower the center of gravity and make them less likely to tip.

Building a safer tanker
Unlike many dry vans, most tankers are filled to the top, distributing the load. Where a van might have most of the load and most of the weight near the floor of a trailer, a tanker will have an inherently high center of gravity.

“We looked at our whole tanker fleet,” Mitchell says. “We tried to evaluate the instability of a tanker and figure out how to improve it.”

This isn’t easy on a typical tanker. In addition to the large bulbous tank, tankers that haul cryogenically cold gases also have piping, transfer controls and a pumping system as part of their design. Tinkering with any part of the trailer would create another challenge with those systems.

“The height of a tanker is mainly just the size of the tank sitting on the frame and the subframe,” Mitchell says. Any changes in tanker design also could cost capacity, he says.

So Praxair engineers and Amko – Praxair’s cryogenic trailer, mobile high pressure and stationary tube rehabilitation subsidiary – focused where it made sense: the subframe. The company redesigned the support braces that tie the tanker to the subframe, making it wider and heavier but shorter. This had two effects: It created a wider base to improve stability, and lowered the tank by 10 to 12 inches without compromising integrity or capacity.

In addition to the shorter center of gravity, lowering the subframe had other benefits, Mitchell says. “The operating equipment was also lowered. This improved ergonomics and maintenance. All the process piping was easier to reach.”

The company now is ordering all its new trailers to the new specification; fortunately, this is made easier by owning the manufacturer, Amko. “We can give them a specification, and they can make that component available,” Mitchell says.

For now, the company is replacing mainly older equipment but has looked at retrofitting existing trailers. Such tankers can last close to 30 years in Praxair’s fleet because of the company’s aggressive rehab systems. Mitchell says it’s possible the company could retrofit subframes during rehab, when a trailer’s process piping, running gear and wiring are replaced.

Building a bigger tanker
But Praxair isn’t just building safer tankers: It also has created a monster of a tanker for one of its customers in Fort McMurray, Alberta. The new tanker – which the company dubbed the “Whale” – is a portable storage tank that can hold 16,000 gallons of liquid nitrogen. That’s three times the size of the company’s typical tanker, says Bill Stoll, president of Praxair Services, a subsidiary of Praxair.

The tankers – two have been built, and more are on the way – actually are not used to haul loads. Instead, the company transports the empty tankers to a jobsite and then fills them on location. The innovation was born from the same capacity challenges facing carriers in the United States – not enough drivers and increased demand.

In the case of drivers, Praxair uses both common carriers and its own distribution fleet for deliveries, but the driver shortage has made it difficult to move loads. “We had to come up with something because of the lack of common carriers and our own distribution fleet,” Stoll says. “Common carriers are hard to find. They’re not available.”

The Whale tankers give Praxair better drive utilization at jobsites because tanker drivers are not waiting to offload or load at a fixed location. Several trucks can be offloading while another loads, and since the tanker has three times the volume of a single truck, more product is available at the worksite. In effect, the Whale gives the company a portable terminal closer to its clients.

Customer demand for the product – which in the case of liquid nitrogen is used to purge hydrocarbons from oil field equipment or to cool hot machines before maintenance is performed – also is soaring because the client is extracting oil from the oil sands region of Alberta, near Fort McMurray. As oil prices have gone up in recent years, so has production and the need for liquid nitrogen.

For Praxair, the demand has meant shipping more loads from Edmonton, Alberta – the closest nitrogen filling station – six hours to Fort McMurray. “Up in the Fort McMurray area where the client is, there is no close proximity of liquid production,” Stoll says. “There’s a lot of roundtrip miles and a lot of logistics challenges. We needed large storage capabilities that are portable.”

With the Whale, Praxair’s clients don’t have to worry about running out; and at the same time, Praxair can minimize driver waiting times. “There’s an increasing need for drivers,” Stoll says. “We can help by minimizing the amount of time they’re ineffective and waiting to offload product.”

The company is looking at other applications for the giant tankers. It conceivably could haul product in the tanker, but the current design lacks baffles and would be extremely unstable loaded. Even empty, the company has to worry about the same rollover issue it does with its standard tanker. The Whale has a high center of gravity, which is minimized when it’s empty.

The company took the same “safety first” approach to designing the Whale as it did with redesigning its standard tanker subframe. “From a safety standpoint, we wanted to be well within limits of DOT rules, and we wanted good access to the piping,” Stoll says. “We wanted to build as large as possible, but stay within height guidelines. Empty, we felt pretty good that most of the weight would be on the low side.”

That safety-minded approach permeates the company – whether Praxair is providing greater capacity on a jobsite or reducing accidents en route. By building a safer tanker trailer and designing a bigger mobile storage unit, the company is serving its clients, improving its public image and gaining an edge over its competition.


Innovators profiles carriers and fleets that have found innovative ways to overcome trucking’s challenges.

If you know a carrier that has displayed innovation, contact Avery Vise at avise@ccjmagazine.com or (800) 633-5953.