After the changeover to high strength steel, less material is needed for manufacturing products with the same properties and strength as in the past. As a result, one third of the transport costs has been eliminated and erection has been speeded up by around 20 percent. The benefits of the changeover have been clear to Silos Cordoba for a number of years. The new designs are the result of determined work to put high strength steels to optimum use. The company has been nominated for the Swedish Steel Prize.

”High strength steel offers distinct benefits,” explains José Cabrera Cuevas, Technical Executive at Silas Cordoba. ”Less material is needed than in the past for an equally strong or even stronger product. This has given us great opportunities in the design work, and we have developed very competitive products.”

Lower transport costs and better environment

The market was initially doubtful about the new silos made of high strength steels. Customers expected heavy designs as proof of adequate strength. But the attitude of customers is now more positive, and there is a keen demand for the new silos. Quicker erection is appreciated and so are the fewer trucks needed for
transporting all of the parts.

”Some time ago, a delivery of new silos to Slovakia weighed 1200 tonnes and needed more than 30 trucks,” explains Cabrera Cuevas. ”In the past, a similar delivery would have weighed 1500 tonnes and would have needed 42 trucks. So we saved more than 12 cubic metres of diesel oil by switching to high strength steels. In addition to the cut in costs, the emissions also decreased.”

The production of silos is entirely customized. High strength steel strip is roll formed at the factory directly from a coil, and is punched and cut into finished cover sheets of exactly the right shape. The factory also includes production lines for roof parts, load-bearing structures and other parts needed for every silo.

20 000 cubic metres

The thicknesses of the high strength cover sheets vary depending of their locations on the silo. The higher up, the thinner the sheets. Every silo is basically ”tailored” to the order. The span of the silos produced is wide – ranging from small silo buildings measuring only a few metres up to the largest units that are more than 30 metres high and upward of 20 metres in diameter. The volume of the largest silo is about 20 000 cubic metres. Around 1200 – 1300 cover sheets are needed for the biggest silo, in addition to a multitude of load-bearing structural parts.

Silos Cordoba uses high strength, hot-dip galvanized sheet steel with minimum yield strengths of between 460 and 500 MPa for the cover sheets. An untreated, hot-rolled steel with a minimum yield strength of 600 MPa is used for the load-bearing structural parts. Plans are afoot to use steels of even higher strength, and the company is studying the possibility of going up to 700 MPa.

The determined work of Silos Cordoba has gained the involvement of the entire company. In addition to being profitable to the company and its customers, the surrounding world has benefited by reduced transport work and consequently lower emissions. For its work on the high strength steel silo, Silos Cordoba has been nominated for the Swedish Steel Prize 2008 design award. Regardless of the results of the nomination, the company has gained new opportunities in which high strength steels have come to stay.