Eddy current testing of austenitic pipes with longitudinal welds

The Technical Control Board Bavaria presents this study explaining the results of a great number of measuring tests and the physical correlations between testing frequency, phase, amplitude, and flaw dimensions, established for a variety of pipe dimensions. The most interesting result of the study is that sensitivity adjustment by means of bore holes alone is not suitable and should be supplemented by tests including additional, artificial flaws (such as inside grooves), natural flaws, at least in case of first inspection. The results also show that in addition to the outside diameter, the pipe wall thickness is an important value to be considered for better sensitivity adjustment. (orig./HP)