Both of the convex and concave type of corrugated tubes can be
created by this machine. A schematic illustration and photographic
representation of the tubes are shown in Fig. 3. Geometric specifications
of the tubes are tabulated in Table 2, where e, S, b and P, are
the geometrical properties of the corrugation as illustrated in
Fig. 3(a). It should be noted that, corrugating causes the tube length
reduction. Hence, the initial length of the corrugated tubes (before
corrugating) was chosen somewhat higher in comparison with the
smooth tubes. Finally, the length of the all corrugated and smooth tubes became the same. So it can be concluded that, in the same
length of the tubes, the surface area of the corrugated tubes is more
than the surface area of the smooth tubes, and this is one of the
corrugated tubes advantages when they are produced by said
method.