Two-layer pipe system for hydraulic and pneumatic conveying of abrasive media. The inner pipe is evenly hardened to 63 HRC. The thickness of the pipe wall is determined specifically for the application. The outer pipe is pressure-bearing and protects the inner wear layer from acting torsional or bending forces. TWIN PIPES can be equipped with a wide variety of weld-ends or flange connections. In addition to straight pipes and bends, special shapes such as reducers, T-pieces, Y-pieces, etc. can be produced. In comparison, the ESSER TWIN 700 series has a service life of 5 to 6 times that of conventional steel pipes. The 700 series are successfully used in many different industries worldwide for decades.