A continuous welding machine (1) for welding facing sides of a pipe blank (15) bent from a material blank is provided, having a guide strut (2) for guiding the sides of the blank (15) to be welded to each other in the direction toward a welding device (3). Pipe guides (4, 5) arranged about a periphery of the guide track designed for the pipe blank (15). For the continuous welding machine (1) according to the invention, the pipe guides (4, 5) and the guide strut (2) are adjustable in the radial direction relative to a guide axis (7) for adapting to different pipe diameters, and the guide tracks (8, 9) of the guide strut (2) allocated to the sides of the pipe blank (15) to be welded and also arranged on opposite sides of the guide strut (2) are arranged at an angle to each other in a plane extending through the guide axis (7). With the help of the continuous welding machine according to the invention, selected pipes with different pipe diameters can be produced alternately.