the effect of forming a melting region which forms a bead when pressing occurs the pipe projection of the pipes being trimmed to a defined size application_number US 201113704090 A description fig1 shows the pipes 1 clamped in the clamping fixtures 2 before the trimming on the trimmer 3 there are fixedly mounted trimmer stops 4 whereby the lengths of the pipe projections 5 can be trimmed exactly to size it is also ensured that the same bead is produced in every welding operation in fig2 the clamping fixtures 2 have been moved toward the trimmer 3 until they are against the trimmer stops 4 whereby the exact length of the pipe projection is defined in a further step the clamping fixtures 2 with the pipes 1 clamped in are moved apart again in order to replace the trimmer 3 by the heated tool 6 as represented in fig3 the heated tool 6 has heating stops 7 whereby a controlled adjustment for contacting the heated tool can be carried out if necessary the heating stops 7 are formed in such a way in comparison with the trimmer stops 4 that they are up to 0 5 mm shorter in order to ensure that the pipe projection 5 comes into contact with the heated tool 6 on both sides.