The demands on modern machine parts, i.e., bearings, are increasing constantly. To ensure that highly clean steel is used, a number of different test methods are commonly used. In the field of test methods the ultrasonic immersion testing has reached a dominant position. This paper will give a short comparison of the ASTM E 588-03 and the SEP 1927 standards and will point out some experiences the authors have made using ultrasonic testing as a tool to increase steel cleanliness and using ultrasonic testing and blue fracture testing as complementary test methods. To be able to use ultrasonic testing as a powerful tool, a number of side aspects like the geometry of the test piece, the structure of it, or the frequency of the used ultrasonic-probe are important. This will be demonstrated by showing results from testing and incoming inspection.