Abstract: Many pipes and piping systems are partly or totally inaccessible from the outside, e.g. by being isolated, lying underwater, or being buried in soil. Therefore, it is not possible to detect defects like cracks or corrosion without removing the isolation or uncovering the pipe itself which is very costly and in many cases utterly impossible. For these kinds of problems long-range inspection systems are needed. For corrosion testing of areas of light poles and pipes ultrasonic based testing systems are already available1-3. However, the systems in their present form are not very well suited for SHM purposes due to size and costs. In order to cover a complete industrial plant with a large number of transducer units, new approaches for measurement hardware, sensor technology, and data evaluation are necessary.