1.1 This practice describes the selection of single-element hard-face ultrasonic search units for which flat-entry-surface reference blocks can be used for examination of steel with convex cylindrically curved entry surfaces.

1.2 The scope of this practice includes the determination of search unit characteristics and radius of surface curvature of the material for which no gain correction is required, or, if a larger search unit is used, the computation of the additional gain required to allow standardization with a flat reference block and examination on a curved surface.

1.3 This practice is intended for use during contact examination of convexly curved steel material using round flat face, piezoelectric search units for longitudinal ultrasonic wave generation in the frequency range from 1 to 10 MHz.

1.4 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.