This part of ISO 4992 specifies the requirements for the ultrasonic examination of steel castings (with ferritic structure) for highly stressed components, and the methods for determining internal discontinuities by the pulse echo technique. This part of ISO 4992 applies to the ultrasonic examination of steel castings which have usually received a grain-refining heat treatment and which have wall thicknesses up to and including 600 mm. For greater wall thicknesses, special agreements apply with respect to the test procedure and recording levels. This part of ISO 4992 does not apply to austenitic steels and joint welds