A method and a device for welding plastic pipes (1) made of thermoplastic material by a butt-welding method, wherein the pipes (1) are held in a coaxial position in relation to one another by clamping points (2), are trimmed by a trimmer (3), which can be brought between the clamping points (2), and are heated up by heated tools (6), which can be fitted in place of the trimmer (3), wherein the heating of the free pipe ends (8) to be welded has the effect of forming a melting region which forms a bead when pressing occurs, the pipe projection (5) of the pipes (1) being trimmed to a defined size.