Ultrasonic instruments are now firmly established as inspection tools in the electrical industry. At Westinghouse, in the role of a consumer, the instruments are used for the inspection of incoming raw materials. The company, under the classification of a producer, uses them for the inspection of finished and semifinished products. In this last classification, ultrasonics are used both for the inspection of materials, and for the control of processes. For these tests the two types of ultrasonic instruments previously described in this symposium are used, that is, the type of instrument using the principle of time of travel of the wave through the material being tested, and also the instrument using the principle of the resonant wave in the material. In the role as a consumer, a program of testing some of the largest steel forgings is underway with the idea of gathering as much information as possible about the general condition of these forgings so that the design engineers can more intelligently and with greater assurance apply their safety factors, thus permitting them to more fully utilize the inherent properties of the material, while at the same time making certain that no injurious conditions exist. This program, is being applied to all large turbo generator rotor forgings. These rotors vary in size from about 20 in. in diameter and 10 ft. in length to 50 in. or more in diameter and 30 ft. in length with some weighing over 150,000 lb. For these tests, the Supersonic Reflectoscope is used and the rotor is tested both longitudinally and diametrically as shown in Fig. 1. This photograph was taken at the beginning of the program and shows the test being applied to an almost completely machined rotor. At the present time the testing is done before machining except for a smooth over-all cut taken to provide a surface suitable for ultrasonic inspection.