ISO 17577:2006 specifies a method for the automated and/or manual ultrasonic testing of uncoated steel flat products for internal discontinuities by the reflection method. It is applicable to non-alloyed or alloyed steel flat products, in a nominal thickness range of 6 mm to 200 mm. However, this standard may be applied to austenitic and austenitic-ferritic steels, provided that the difference between the amplitude of the noise signal and that of the echo detection threshold is sufficient for the limit fixed. Unless otherwise agreed, for testing of steel flat products for welded steel tubes, ISO 12094 applies.