By combining copper-DHP as a common material in water pipe construction on the one hand, and using steel alloys, for example as a corrugated pipe for the construction of compensators for vibration and thermal expansion, on the other hand, the joining of the two very different metals is challenging. The article presents a welding application developed in the Laser Zentrum Hannover e.V. in cooperation with the company Flexxibl GmbH Braunschweig in comparison to the conventional hand soldering process.