Above: The “cost stable” stainless does not rely on expensive alloying elements such as nickel and molybdenum.

Twenty-first century stainless products could help solve the rail industry’s tankcar dilemma

April 2015 - In the aftermath of five more oil train derailments in February and March 2015, U.S. and Canadian officials are working to finalize a proposal for new safety regulations—rules that call for thicker hulls, mandatory thermal jackets and electronically controlled brakes able to automatically stop all cars simultaneously. Systems today merely stop cars in sequence.

Sarah Feinberg, acting administrator of the Federal Railroad Administration, said disaster prevention calls for an “all-of-the-above approach; one that addresses the product itself—the tankcar [oil] is being carried in—and the way the train is being operated,” but added “there will not be a silver bullet for solving this problem.”

The “silver bullet” that may be escaping the notice of railroad authorities is stainless steel, suggests Ken Grantham, executive vice president of Crompion International. The Baton Rouge, Louisiana-based company engineers specialty and low-nickel stainless for a wide range of industries.

Following a lethal derailment of a train carrying ethanol in 2009, railroads and railcar owners focused on reinforcing new vessels with improved protection and thicker carbon steel plate. 

Exploration of alternative materials and the metallurgy used to develop them—such as Crompion’s Cromgard line of stainless steel products—could offer multiple advantages should the rail industry include it under new standards. Case in point: the corrosive nature of crude, ethanol, flammable gases and other chemicals poses a different problem for tanker cars, but the integrity of tanker interiors is not up for discussion right now.

More than skin deep

“We’re hearing a lot of discussion about tankcar failures due to structural integrity from outside impact,” he says. “But there’s very little conversation about failure occurring from the inside out due to corrosion. This is where stainless can offer a significant advantage over carbon steel not just in reduced maintenance and life cycle costs but lower thermal conductivity and higher strength without the need to add weight.”

Cromgard, explains Grantham, is a “cost stable” stainless steel because its chemistry doesn’t rely on expensive alloying elements like nickel and molybdenum. Stainless steel conductivity isn’t the same as with carbon steel. “Heat travels through carbon steel much faster,” he explains. “During a thermal event [fire], stainless steel offers greater heat resistance. If a car made of stainless or equipped with a stainless steel jacket caught on fire, first responders would have more time to reach the scene.”

Crompion’s products resist scaling, oxidation, sulphur-bearing atmospheres, hot gases and fumes with minimal tendencies toward brittleness when exposed to temperatures between 842 and 1,022 degrees Fahrenheit over many hours. Lower maintenance and longer service life have helped the low-nickel stainless displace coated carbon, CorTen and aluminum in numerous applications.

The American Petroleum Institute and ASTM International recognize this family of new stainless steels because tests proved its ability to reduce the weight of stationary tanks and make pipelines more corrosion resistant. Fire Departments across North America, like the Neshannock and New York City Fire Departments, specified Cromgard for their trucks to combat salt and heavy wear. 

“The tanker car is a different animal,” Grantham acknowledges. “We were trying to approach railcar builders with the option to choose a superior product that could reduce weight without sacrificing strength before the Lac-Mégantic 74-car freight train derailment in Quebec in 2013.”

Grantham began to investigate the freight rail market after observing the industry’s demand for stainless was very small. He discovered the only stainless products approved for use were very expensive and lacked the necessary strength.

On track

The Code of Federal U.S. Regulations states tankcars that do use stainless must be built of Type 304 or Type 316 grades, which “have been around for 100 years,” says Grantham. “There have been dozens of advancements in stainless steel products that could be used for these applications but the standards are not currently reflecting that.”

Persuading regulators to update standards to allow the use of advanced products like Cromgard has been an uphill climb. Unlike the automotive and aerospace markets, the rail industry’s wheels tend to turn slowly when it comes to adopting newer materials. More than 90 percent of tankcars in the U.S. are still made from carbon steel.

Cromgard has gained a toehold in building hopper cars and gondolas that haul such aggregates as coal and gypsum. “The suppliers that move these commodities see firsthand the impact of corrosion and abrasion on their cars,” says Grantham. “Standard coatings are expensive to apply on the front end and have a limited life cycle. The cost of stripping out and relining a car in its 50-year service life is very expensive and doesn’t take into account other repairs. The bottom line for these companies is that if a railcar is parked, it’s not making money.”

Cromgard users see the return on investment based on its performance advantages versus carbon steel cars, Grantham says. 

Crompion finds it difficult, however, to infiltrate the tankcar arena, which is dominated by several railcar manufacturers, railcar leasing companies and large-volume carbon steel producers. Pursuing acceptance of stainless as a viable alternative is not about “selling something. Our mantra has always focused on safety first,” says Grantham. “This is a conversation about safety and total cost of ownership.”  

Cost of doing business

Nearly 500,000 carloads of crude oil traveled by rail last year, a substantial increase from 9,500 recorded in 2008, according to the Association of American Railroads. Crude now accounts for 1.6 percent of total carloads for U.S. railroads, AAR data show. 

David Willauer, who chairs the Subcommittee on Crude Oil Transportation at the Transportation Research Board and the transportation manager at IEM, a global security consulting firm, said crude oil wasn’t categorized as hazardous material until a few years ago but, “because of the huge increase in the volume being transported, it now presents a problem for railroads.” 

Oil and rail industries are asking for 1⁄2-inch-thick walls for tankcars versus the proposed standard for 9⁄16-inch-thick hulls. Thicker shells mean less oil inside, and a cost difference that can mount quickly.

“Because of our unique chemistries we’re able to produce thinner plate without sacrificing strength or resistance to puncturing,” Grantham says. “If by using stainless we’re able to keep a 100-car train from growing to a 130-car train, that’s significant, especially if you are hauling the same amount of oil.”

Congestion is another unintended consequence, he observes. “If you add 30 percent more tare weight to meet the new safety standards you have to subtract equivalent pounds in oil. That means adding more cars to make freight. At that point your train is carrying 30 percent more train than freight, which may mean adding another locomotive. You have to ask how efficient that is.”

The improved mechanical properties of Cromgard can also save dollars on the fabrication floor. “We can maintain strength with thinner gauge stainless,” Grantham says. “If we were to use the current standard’s hull thickness of 7⁄16 inch to make a jacketed CPC 1232 car, that means 30 percent less welding, 30 percent less heat treatment and 30 percent less fabrication when compared to thicker carbon steel. If you can put 30 percent more payload on [any vehicle], that is significant.”

The CPC-1232 casualty prevention circular AAR released in 2011 dictates new tankcars built for transporting crude oil and ethanol adhere to specifications for half-height shields, thicker tank and head material, top fitting protection and pressure relief devices. But a Feb. 16, 2015, oil train derailment on a CSX line in West Virginia and the simultaneous CN crash and explosions in northern Canada, both involving CPC-1232 cars, seem to underline the fact that structural design alone can’t mitigate the risks associated with combustible untreated crude oil.

“We can combat thermal management, corrosion resistance and the safety concerns involving punctures and fractures by using metallurgy as a tool that could contribute toward a solution,” Grantham says. “We continue to discover new chemistries capable of replacing higher cost alloys yet engineered for performance.” MM