Tubes of this type include flexible duct elements used in the erection of concrete structures with the application of pre-stress effect. Such effect is used in the construction of monolithic bridge spans, buildings, foundations, and other facilities, where flexible carbon steel pipes are used as duct tubes. The duct tube is also used as a framework in anchor holes.
These tubes are made of corrugated stainless steel. When connecting pipes with socket couplings, the length of a duct tube rod is practically unlimited. The duct tube is made in a form of the corrugated pipe, which provides, as a double thread, high radial resistance and stiffness necessary to take up local strengths and wet concrete pressure. The tube's material is carbon steel (S1) with a width of 0.30-0.50 mm. The length of flexible duct tubes is 5 m. Coupling dimensions are 0.3 - 1.5 m. The diameter (DN) of the flexible duct tube is 30-205 mm. The thread pitch is 24+1.5 mm. The temperature range, at which the duct tube can be used, is from -50°C up to +100°C.