The invention relates to a Device (10) for separating a tubular web (11) in two flat webs (12, 13) with an adjustable blade (20) for cutting the tubular web (11) and with a pulling device (30) which impinges the blade (20) with a tensile force (K) on a folding edge (14) of the tubular web (11) wherein the pulling device (30) is configured in a way that the tensile force (K) is adjustable depending on the tubular properties of the tubular web (11) and that the tensile force (K) can be mainly kept constant with constant tubular properties independent from the tubular web (11).