a method and an apparatus for the manufacture of pipes of thermoplastics with transverse profile features comprises mold segment halves which are circulated by twos on a molding path . a conveying device of the type of a gantry crane is provided for recirculation of the mold segment halves . on a conveying bridge that bridges the molding path , provision is made for two conveying carriages , which are movable in opposite directions and crosswise of the direction of production and which have mounted on them a downward conveying arm with a holding device for a respective mold segment half . provided downstream of the downstream end of the molding path are parking positions for additional mold segment halves , those of which that are closest to the molding path being carriages which are movable out of the path of displacement of the conveying arms .