Non-ferromagnetic tubes such as aluminum and brass tubes have relatively low electric conductivity. Special coils for eddy current testing are required as a result.
The following test systems are used for this purpose:

DEFECTOMAT: The DEFECTOMAT product family is used for the precision testing of the material surface of non-ferromagnetic tubes for point and transverse defects.

CIRCOGRAPH: The CIRCOGRAPH test systems reliably detect longitudinal defects thanks to their rotating test heads that scan the material surface of the steel wire without making contact.