ISO 17577:2016 specifies a method for the automated and/or manual ultrasonic testing of uncoated steel flat products for internal discontinuities by the pulse echo technique. It is applicable to non-alloyed or alloyed steel flat products, in a nominal thickness range of 6 mm to 200 mm. However, this International 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 10893-9 applies.Other techniques of testing (e.g. by transmission) or other test equipment may be used at the manufacturer's discretion, provided that they give identical results to those obtained under the conditions of this International Standard. In the event of a dispute, only the method defined in this International Standard will prevail.Testing of flat products, of thickness less than 6 mm and over 200 mm, may be the subject of special agreements between the parties concerned.Testing is normally carried out in the place of production or on the premises of the supplier.