Abstract: In an apparatus for rolling the walls of a tube in order to decrease the wall thickness and so increase the length of the tube by the use of pairs of rolls of which one roll is outside the tube wall and the other roll is inside it and in which relative axial motion and relative rotation takes place between the tube and the roll pairs, an increase in the possible length of tube which may be rolled is produced by having all the rollers carried on means extending from a common support structure on which a holder for one end of the tube is also carried.

Abstract: For the production of coaxial corrugations in the walls of thin-walled tubes with very tight tolerances, the invention provides a device having jaws adapted to be moved equally in opposite directions and which press against the ends of the tube so as to have a corrugation formed therein so as to feed the tube wall axially towards the corrugation in the process of being generated. The jaws are moved by means of a central lead screw with screw threads of opposite hand.