Gleaming prospects: Hot-dip coating line in Bochum turns 25

Over ten million metric tons of flat carbon steel – enough for more than 30 million compact cars – galvanized here since start of operations.

At around 70 meters it is one of the tallest buildings in the city and a landmark on the A 40 autobahn: Steel’s hot-dip coating line in Bochum. The roof offers a unique panoramic view across the Ruhr region. Technically the line beneath it also has plenty to offer – it has been producing high-tech steels for 25 years. The line, which is known as FBA 7, started production on May 12, 1992. Since then it has coated over 10 million metric tons of carbon flat steel – enough for the auto industry to produce more than 30 million compact cars. “Thanks to numerous upgrades our hot-dip coating line has remained state-of-the-art and continues to meet the growing and specific requirements of our customers,” says Niels Lohmeyer, who is responsible for all Steel’s hot-dip coating lines.

The newspapers hailed it as a “new dimension” and a “milestone in the company’s history” when the 300 million deutschmark galvanizing line started up in Bochum. Predictions of “gleaming prospects for hot-dip galvanized sheet” were proven right. FBA 7 has now been running almost round the clock for 25 years and still has good workloads, as the bath in molten zinc gives the steel strip an attractive, corrosion-resistant surface.

Krupp’s first hot-dip coating line

The “anniversary” unit in Bochum went into operation in May 1992 and was Krupp’s first hot-dip coating line. Today Steel has nine such production units. FBA 7 has a capacity of roughly 45,000 tons per month. Around 80 people work on the line, while in total the site employs more than 2,000 people including some 150 apprentices. The site adjacent to the A 40 autobahn also includes a hot strip mill, two pickling lines, a cold-rolling mill, an electrogalvanizing line, various small steel coating lines and an in-house apprentice training center.

Bath in 450°C molten zinc protects flat steel from corrosion

A hot-dip coating line produces galvanized steel strip in a variety of sizes. “Hot-dip galvanizing” is a continuous process in which coiled steel strip is welded together, annealed, drawn through a bath of molten zinc and then cooled. The steel strip is then finished to customer requirements in various downstream operations and after re-coiling is ready for packaging and shipping. The building is so tall because after being dipped in the bath of 450°C molten zinc the strip has to be cooled: For this it is drawn vertically upwards in the tall tower and cooled by fans until the zinc hardens. Applications for these corrosion-resistant materials include household appliances as well as hoods and crash-relevant parts in the automotive industry.