Abstract: The bellows sections welder according to the invention comprises a bed carrying a stationary support and a movable support with a driver chuck and a driven chuck, respectively, which chucks are kinematically interconnected. The bed further carries a welding torch and a yoke disposed between the chucks and intended for centering the ends of bellows sections being welded. The movable support is driven by at least two pneumatic cylinders symmetrically arranged with respect to the longitudinal axis of the welder. Viewed in the direction of the work movement, the movable support is preceded by adjustable stops and followed by a means to receive welded bellows sections.