Rail car builder offers 6351 for DDGS transport

Trinity Rail sees growth in U.S. ethanol industry, distillers dried grains market
By Tom Bryan | November 01, 2002
Trinity Rail Group (TRG), a division of Texas-based Trinity industries, manufactures a quad covered hopper car with 6,351 cubic feet of capacity. This uniquely oversized hopper car, simply referred to by the company as the "6351 CF" model, has been optimally designed to transport distillers dried grains. In fact, Trinity designed the car with DDGS in mind.

"Producers and marketers of distillers grains might be especially interested in the 6351," says Andrew Brown, director of engineering and agricultural/mineral freight cars for Trinity Rail Operations, "because it has structural advantages over traditional hopper cars that are designed to carry a wide range of commodities and products. In designing the 6351, we went out to the facilities - talked to the companies that handle and ship DDGS (and similar products) - and designed a car that made sense for them."

More specifically, Brown said, heightened U.S. ethanol production prompted the company to see where its proven line of covered hoppers would make sense to the ethanol industry.

"Our largest "through sill" hopper car had 5461 cubic feet of capacity (CFC), with three hoppers, sized for general grain service," Brown said. "A simultaneous need for a car to carry SEM (solvent extracted meal) in a similar density to DDGS prompted us to design the four hopper 6351 CF, the largest car of its type."

The Specs

The 6351 CF has large 30" x 30" discharge gates, and can be used in any low density grain service in the range of 28-40 lbs/CF. According to the company's specification sheet, the 6351 CF is an all-steel covered hopper car with four hoppers, a through tubular center sill, curved sides and a curved roof. The cars are furnished with a continuous trough-type roof opening - which is about 40 feet long and two feet wide -with discharge outlets on the bottom of the car. The car is about 70 feet in length and over 15 feet high.

Empty, the 6351 CF weighs roughly 66,000 pounds, a fraction of the 286,000 pounds it weighs after being fully loaded with 220,000 pounds of DDGS. Note: Distillers dried grains weighs approximately 28-32 pounds per cubic foot.

Why a larger car?
"DDGS is considered a lighter product, so we were able to add more storage capacity," Brown explained to EPM. "The design is optimized for the product."

Typical grain hopper cars are 4,000 to 5,000 cubic feet, Brown said. There are larger cars also for various products. These cars typically range from 20 feet to 89 feet in length. The widely used 4350 was able to handle a much smaller load.

"The 6351 is larger and better designed," Brown said. "We focused on the products it would carry specificity and purchased a design that would best fit the needs of the end user."

Trinity Rail Vice President of Marketing Jim Sobie said due to the light density of the DDGS product, standard grain hoppers do not provide the cubic capacity necessary to achieve the higher payloads that railroads allow. The 6351 cubic foot hopper car was produced by Trinity to achieve a combination of size and weight to allow for a more optimum payload of DDGS, he said. The car is lighter in weight and provides for a higher hopper side sill, allowing easier access to the gates and vibrator brackets for unloading personnel. The car is equipped with continuous trough hatches which allows the car to be loaded while in motion. The round side design promotes better loading efficiency and maximum use of available cubic capacity. The tube center sill reduces the direct downward force of product on the outlet gates making operation easier. Vibrator brackets are included in this design to accommodate vibration to the car when necessary.

In addition to the 6351, Trinity's product line includes a 30,000 gallon tank car sized specifically for ethanol as well as high capacity grain hoppers to meet the rail transportation needs for the inbound as well as the outbound products of the ethanol marketplace.

The factors that influence the design of hopper cars are the product density(weight per cubic foot), angle of repose(angle formed when product is at rest), whether the product is food-grade, the moisture content of the product, as well the way in which the product is loaded and unloaded. Sobie said Trinity has developed extensive relationships throughout the ethanol industry and sought to understand the specific needs of shippers and receivers as the 6351 cubic foot hopper was designed.

The 6351 CF line has been running for just over a year and will continue to run for several years. The company has built over 300 6351s and has a couple hundred more on order, according to Greg Yates, Trinity senior market analyst.

Yates told EPM the company currently manufactures three cars a day, but could produce as many as 12, if demand called for it.

"We see great prospects for the 6351 in the near future, he said. "The growth of the ethanol industry is a big part of that."

What about flowability?
Inevitably, there are sometimes problems associated with the flowablity of DDGS. Especially during certain seasons of the year, the product has been known to stick, or clump together, making it difficult to remove from rail cars.

"That was a consideration in our design," Brown said. "Generally speaking, the steeper the car walls are, the better the product unloads. The hopper sheet angle is a trade-off - you can make it steep enough to get almost anything out, but the trade off is loss of space. You loose cubic feet at the floor level with the steep angles. So you seek a balance with the flow angle, depending on the commodity you're dealing with."

What goes into the design?
Several years ago, Trinity made the move to 3D design software, Pro/Engineer. Each component and fabricated part is modeled, evaluated, and test fit on the computer. This allows design, tooling, and stress analysis to progress almost simultaneously. The design is validated on the completed railcar in many AAR (American Association of Railroads) defined tests, such as curve negotiability, brake force tests, dynamic and static squeeze tests.

"Trinity's long line of successful hopper car design features flow into the 6351 CF car. The car has many features important to shippers, receivers, and end users such as the through center sill for durability and the high side sill for excellent vibrator bracket and outlet gate access," Brown said. "The most important feature to a DDGS producer is simply the support and strength of the company behind the car. The car will continue to be tailored for the needs of the marketplace, including advances in unloading difficult products like DDGS during the hot summer months and maximizing payload by car design."

Purchasing & Leasing
According to Sobie, Trinity Industries is the leading manufacturer of rail equipment in North America. A complete line of tank and freight cars, as well as a wide variety of railcar services, are available to the company's customers. Trinity can provide flexible financing structures and railcar management services to match the ever-changing needs of railcar customers. Among the financing alternatives are net lease, full service lease and outright pur"Under a net lease arrangement, Trinity provides the financing for the asset," Sobie told EPM. "This structure is favored by customers who wish to handle maintenance and the associated administrative functions themselves. A full service lease includes the financing for the asset as well as the provision for maintenance and administrative services over the term of the lease. These services include shopping of cars when in need of repair, registration of the rail car in UMLER, payment of ad valorem taxes, mileage accounting and auditing and other administrative duties."

For customers who wish to purchase cars, Sobie explained, Trinity can provide railcar management services which allows customers to avail themselves of the same services that are provided by Trinity under a full service lease. Sobie said Trinity currently provides railcar management services for over 75,000 railcars across North America.

Industry Outlook
"Trinity is excited about the prospects for ethanol and the growth this market has achieved thus far," Sobie said. "The ethanol industry is an important market for Trinity and we will continue to work with producers and marketers of ethanol and related co-products to meet their expanding rail transportation needs."