Abstract: In a method for the corrugating of metal tubes in which a smooth tube, preferably a longitudinally seam welded smooth tube is passed continuously through a bushing and acted on immediately behind the bushing by a corrugating tool, in which tool a corrugator disk having a larger inside opening than the diameter of the smooth tube is mounted for free rotation eccentrically in a corrugator head which can be driven in rotation, and the corrugated tube is deflected from the direction of manufacture in the direction towards the place of action of the corrugator disk in order to obtain a deeper corrugation.

Abstract: The method of U.S. Pat. No. 3,866,315 is improved by brushing copper particles also on the other side of the niobium ribbon prior to, e.g., rolling and by increasing the layer's thickness by an electrolytic process. That layer will be on the outside of the tube. Tin is subsequently deposited thereon; and by means of annealing, the tin is caused to diffuse through this outside copper layer and into the niobium to form a uniform Nb.sub.3 Sn layer.

Abstract: In the production of longitudinally welded pipes, the metal strip is treated with a chemical deoxidizing agent, such as a hydrazine compound, to remove oxides from at least the strip edges, prior to arc welding, to provide an improved weld.