Longitudinally welded with wide inside corrugation. The wide range of dimensions of round cavity pipes covers diameters from 21 mm to 1,500 mm. A general profile height from minimum 2.5 mm to 8.00 mm allows for the use of these pipes in anchor engineering. The continuous inside and outside profile allows for force-locking anchoring, but also for the construction of cavities e.g. in beams without any problems.