New scrap steel containers save time and US$140,000/year in operating costs

SSAB logistics department wanted to improve the scrap steel unloading process at the Luleå mill. The existing method required a crane to move the scrap from the railroad wagon onto a dump truck (container lorry), that then moved the cargo to mill’s scrapyard. This process consumed 33 worker hours every week.

The goal was to eliminate the need for the crane and dump truck and instead use the mill’s existing forklifts to unload new, railcar-mounted scrap containers that could then be directly tipped into the Luleå scrapyard.

• Weight: The weight of each new container had to be as light as possible to maximize the amount of scrap steel transported — yet the design had to be robust to withstand steel-on-steel impact.
• Compatibility: To mechanically secure the containers onto the rail wagon, the containers’ frames had to be compatible with the stopper and ISO-lock configurations on the existing, standard Green Cargo flatbed rail cars.
• Compatibility, part 2: The scrap containerss had to be compatible with the existing forklift truck attachments used to move the containers on and off the rail wagon and around both mills.
• The shape of the containers had to maximize their tipping angle and have their center of gravity to the containers’ angled front wall to facilitate unloading and minimize carry back.
• Dimensions of the containers must fit within the factory gates of the Luleå mill.
  
  

Design for manufacturing was key. Welds and the number of parts needed had to be minimized. The design also needed to optimize the use of each steel plate to reduce scrap. And the design had to be robust — but also economical. 

The SSAB Product Engineering assignment was to deliver manufacturing and assembly drawings with comprehensive details that, in turn, could be sent out for request for quotes (RFQs) for the containers’ steel fabrication.

With both railway wagons the same length, the three-container per rail car design turned out to hold more steel scrap than the four-container approach.

As with all projects — whether for internal or external customers — Product Engineering used its own innovation workshop methodology, based on the SSAB ONE lean principles, to comprehensively gather and structure input from all stakeholders. This included the operators at the location where the scrap was generated, gathered, and put onto railway cars, as well as operators at the receiving end, where the containers were taken off the rail wagons and unloaded in the scrapyard. Green Cargo, the rail company, was also a key participant in the design input process.

SSAB Product Engineering explored two different design approaches: 1) Making three containers as large as possible for a rail car and 2) making four containers that would also fit on the same length rail car. It was mutually decided to go with the three-container approach since that maximized the load capacity.

Product Engineering’s first concept underwent several iterations to meet all of the project’s requirements, including finite element method (FEM) analysis for four different load scenarios.

Finite element method analysis for the steel scrap containers under one of four different load scenarios.

To withstand the impact of the heavy steel scraps, Hardox^® 500 Tuf wear plate was chosen for the containers’ walls. The design was adapted to use 8 mm steel plate for all of its components, reducing the number of plates needed to build each container and simplifying ordering and inventory.

Drawings of the final, assembled, heavy-duty container for scrap steel.

View of the back and side walls. The economical containers maximize freight handling efficiency, both at the mills and on the railroad.

From initial sketch of the container to fully documented engineering for fabricating quotes took less than six weeks. Through constant two-way communication with all stakeholders, SSAB Product Engineering was able to completely gather all the necessary details, saving both time and the need for engineering rework. 

Stock availability for prototyping was secured by Product Engineering, who also gave technical support to the procurement team during the quotation process and the manufacturing of the container. 

The container kits were manufactured by the SSAB Steel Service Center Oborniki, Poland. Product Engineering’s fully detailed manufacturing documentation, combined with the Oborniki Center’s high expertise and state-of-the-art fabricating equipment, enabled all components to be made within tight tolerances and in a timely fashion. The container kits were then sent to a fabricator in Poland for final assembly and welding using Product Engineering’s assembly documents.

“The scrap steel-handling process from railroad wagon to the Luleå scrapyard went from 33 hours/week to 7 hours/week, while eliminating the need for a crane and a dump truck,” notes Hans O. Andersson, SSAB Procurement/Strategic. “Savings are estimated to be US$140,000 per year. The new containers also free-up a Luleå crane for other uses.”