Abstract: The overlapping edges of a continuously formed tubular configuration of plastic web are fused together between a backup ring and a sealing roller continuously heated by hot air directed against the periphery of the roller. When the heated roller is pressed in sealing engagement against the overlapped edges of the moving film it is rotated due to the frictional engagement of the roller with the film. A portion of the hot air impinges on blades extending laterally from opposite sides of the roller to apply torque thereto and thereby keep the roller spinning whenever the roller is out of frictional engagement with the overlapped edges of the continuously advancing web. By keeping the roller spinning it is evenly heated and hot spots are not allowed to develop as they would if the roller stopped while hot air continued to impinge on it. Cooling air is applied to the sealed overlapping edges after the sealing operation has been performed.