Heat-to-coat: New line concept for pickling and galvanizing of strip

With a capacity of 500,000 t/year, an output of up to 180 t/hour and a vast range of galvanized strip (up to 6.35 millimeters in thickness and 1,854 millimeters in width), the new “heat-to-coat” line of Nucor Steel Gallatin in Ghent, Kentucky (USA) sets new standards in the field of hot strip galvanizing.

To Nucor Steel Gallatin, domiciled in Ghent, Kentucky, U.S.A., systems supplier SMS group delivered a new “heat-to-coat” pickling and galvanizing line, including engineering, process technology, furnace equipment, pickling and galvanizing technology as well as electrical and automation systems, all from one source. The line was put on stream in September 2019 and, since then, has continually increased  capacity. Meanwhile, the line produces even strips with socalled galvannealed surfaces. In a “heat-to-coat” line this is a worldwide unique achievement. Right behind the air knives, the liquid zinc is inductively reheated and allows a zinc-iron alloy layer to develop. Even strips of maximum possible dimensions, i.e. 6.35 millimeters thickness and 1,854 millimeters width, can be produced with galvannealed surfaces. This is another one of the line’s unique features.

The “heat-to-coat” process based on SMS group's patented technology excels with its high profitability, as all processes take place in a single facility. The process permits the production of galvanized steel strip with durable corrosion protection, an appealing visual appearance, as well as an increased mechanical load-capacity while still maintaining low production and investment costs. Due to the integrated inductive galvannealing furnace the line is also able to produce galvannealed strips.

There is a broad area of applications for galvanized hot strip, especially in construction, transportation and automotive industry. Furthermore, it is possible to substitute galvanized cold strip with hot strip.

The “U-shape” design allows a quick and easy bypass of the coating section in order to use the line as a continuous pickling line and produce just pickled and oiled material. Since entry and exit are located side by side also fewer staff is required.

Furthermore, the “heat-to-coat” process stands for an environmentally-friendly production of galvanized material since the whole process takes place in one line and uses efficient technologies. Compared to the conventional process some process steps are even omitted. Another advantage is the inductive furnace which operates with electrical energy and therefore emission free. Furthermore, a special fume exhaust system will be integrated which ensures low emission rates for the whole process.