Sealing the edges (8) on a continually travelling form-fill pipe (9) is accomplished in the sealing zone (10) whereof the edges (8) are treated by the heat and pressure. Upon completion of sealing the edges (8) of a single form-fill and a seal bag the application of the heat and pressure ceases. When formed unsealed edges (8) of the following seal bags are transported to the sealing zone (10), the whole procedure will be repeated. Apparatus to implement the procedure comprises the forming collar (2) determined to shape the packaging material (1) into the hosepipe (9). It passes to the charging tube (3) enabling to shape the edges (8). There is a floating frame (6) integrated with the sealing jaws (4) situated within the sealing zone (10) including the gears (5) that executes the synchronized reverse motion in the parallel direction to the direct axis of the charging tube (3). When the shaped edges (8) slide between the sealing jaws (4) in the duration of their motion, the sealing jaws will clamp and the edges (8) will be sealed. Upon completion of sealing, the whole procedure will be repeated within sealing edges (8) of other form-fills and seal bags.