Abstract: A closure system includes two longitudinally-extending shell members, each having flanges. Each of the flanges have inner and outer surfaces such that in a closed state the inner surfaces of each of the flanges contact one another to form at least one longitudinal seam. Several longitudinally extending ramp pairs are disposed on the outer surfaces of the flanges One ramp of each ramp pair is disposed on the outer surface of one flange and another ramp of each ramp pair is disposed on the outer surface of the other flange. The ramp pairs are inclined away from the longitudinal seam when viewed along a first direction. A clamping rail has an inner surface that includes a guide channel interlocking with the ramp pairs so that the first and second flanges compress the seam. Additional longitudinally extending ramp pairs can be disposed on the outer surfaces of the flanges, in which case a second clamping rail having an inner surface that includes a second guide channel interlocks with the additional ramp pairs.