Kordt GmbH, TVT

Zinc Elephant³ makes screw joints safer

At “Wire 2010” Zink Körner will introduce its Zinc Elephant³, an automatic galvanizing unit for small parts and bulk materials like bolts, screws and connecting elements for offshore applications, which call for superior corrosion protection. Through the efficient use of resources the plant reduces the expenditure on material, energy and reworking, while providing higher coating quality.

Due to the massive expansion of offshore wind-power generation the demand for high-strength hot-dip galvanized bolts, threaded joints, fasteners and other small parts - referred to in the industry as centrifugal parts - is constantly growing. For galvanizing large amounts of these products Zink Körner has developed the Zinc Elephant³. The combination of a high-capacity furnace and fast handling of the baskets and frames achieves throughput rates of up to 5 t per hour.

All process steps - from picking up of the baskets and racks, immersion in the molten zinc bath, centrifuging through to quenching in a water bath - are automated. As parameters such as the immersion time are process controlled, the Elephant achieves excellent uniformity of the zinc layer.

Before a basket is immersed and after boiling up, the surface of the zinc bath is automatically skimmed. This ensures that the surfaces of the galvanized parts are completely free of contamination. Thus Zink Körner fully complies with the extremely exacting requirements the rotor industry places on the quality of galvanized parts.

As the parts are handled very gently during galvanizing, handling damage is minimized. Therefore threaded bolts and similar parts do not require rethreading. This considerably reduces the effort and cost of reworking.

The integrated process control system captures all plant states and stores the data relative to each individual basket. Each batch is completely trackable, meaning a high degree of security for the operator.

The parts can be pretreated without the use of acids. Thus Zink Körner avoids hydrogen embrittlement and the resulting brittle fracture of the steel. This makes the system perfectly suited for the treatment of high-strength steels, which are commonly used in offshore applications.

Thanks to the applied regenerative burner technology, energy consumption can be reduced by up to 20 percent. As the burners never operate under excess-air conditions, the amount of arising zinc ash can be cut by up to 70 percent. This brings down both zinc consumption and the effort required for zinc ash removal.

Zink Körner at Wire 2010 in Düsseldorf: Hall 9, Stand B37