This document specifies the application of the time-of-flight diffraction (TOFD) technique in testing of metals for quantifying loss of thickness due to erosion and/or corrosion. This document applies to all types of corrosion or erosion damage, particularly those defined in ISO 16809. This test applies to unalloyed or low-alloyed steel materials. It applies to components with a nominal thickness e" 6 mm. For smaller thicknesses feasibility tests will be performed to validate the technique. For other materials, feasibility tests are essential too. The TOFD technique can be used here as a stand-alone technique or in combination with other non-destructive testing techniques, during manufacturing and for testing in-service, in order to detect material loss caused by erosion and/or corrosion. This technique is based on analysis of TOFD images established using reflected and/or diffracted ultrasonic signals. This document does not specify acceptance levels.