Mobile dams and traverses in general are usually steel structures moved oil-hydraulically by cylinders. The cylinders used for dams are mainly used to lift the locks. They are very long (6 -10 m) and often require the use of piston rods made of special materials (stainless steel material) with special coatings (NiCr, Ceramax). These cylinders are extremely critical components as no malfunction is allowed. Often, for welded cylinders, the ultrasonic inspection of the weld seams as well as a corresponding certification is required.