A stainless steel drinking water tank manufactured by Lipp, based in Tannhausen, Germany, can hold up to 3,000^{m3 or} 3 million liters of water. The 3 to 5 mm thick stainless steel strip used remains dimensionally stable even with meter-high tanks. This is made possible by stiffening ribs that are formed on the incoming metal strip. The optical inspection system seelectorICam weld from Hema Electronic used by Lipp reduces reworking during quality assurance of the weld seams and thus the risks that could arise from faulty seams on the struts.

Elevated tanks for drinking water storage play a particularly important role in municipal drinking water supplies. Stainless steel is a particularly suitable material for such tanks because it is hygienic and resource-efficient.

As the containers can have a diameter of up to 20 m, Lipp installs them directly on the customer's premises. An assembly ring determines the intended size of the container and brings it into a perfectly round shape. A machine developed by Lipp then unrolls a strip from a steel coil, which receives the reinforcing ribs attached at 75 cm intervals in the roll forming machine. The container is then welded fully automatically on both sides.

Monitoring with a clear image

The visual inspection of the weld seams is carried out by the seelectorICam weld. The intelligent camera system provides a clear image of the working area even in extreme lighting conditions around the arc, enabling monitoring on the monitor. The video system inspects the welded seams inside and outside at the same time and at the same speed as the container is being erected and provides the fitters with the results for further processing on the monitors. Important parameters for the welding process such as amperage and voltage, wire feed or gas quantity can be stored in the system and used for the weld seam inspection. Manual rechecks of the seams are reduced to the points detected in the process and are rectified immediately.

Automated camera-supported weld seam monitoring has another advantage for Lipp: "Our employees must be able to adjust the parameters depending on the requirements of the tank, detect welding errors and carry out manual improvements. For this alone, we would actually need three to four qualified experts per tank. However, they don't grow on trees. The automation provided by the Hema quality assurance system relieves us of some of these tasks," says Matthias Kuck, Head of Drinking Water Systems at Lipp.

Security risks minimized

The Hema quality assurance system seelectorICam weld works so efficiently that other methods of checking the strength of the weld seams, such as X-rays, become unnecessary. "Having a tank of this size X-rayed is very costly and time-consuming and is unnecessary when using our system, as we check all the relevant areas for workmanship and quality during assembly," says Oliver Helzle, Managing Director of Hema Electronic.