Figure 1-10. ASTM Reference Blocks

Table 1-5. Reference Standard Metal Travel Tolerances.

TM-1-1500-335-23 Nondestructive Inspection Methods Manual
Page Navigation
55

T.O. 33B-1-1 1-54 Figure 1-10. ASTM Reference Blocks. a. When applicable, Table 1-6 may be used as an aid if the required flat-bottom hole, (FBH), reference standard is not available. The second column lists relative amplitudes of echoes from successive sizes of FBHs. For example the signal from a #5 FBH is 4 dB larger than the signal from a #4 FBH, so the instrument gain would have to be decreased by 4 dB if a #4 FBH were available but a #5 FBH was the required standard. If a #5 FBH were available but a #2 FBH were required, the instrument gain would have to be increased 16 dB (7+5+4) for the inspection. Table 1-6. Relative Signal Response from FBHs in ASTM Blocks. FBH Number (size in 64ths of an inch) Difference (dBs) From previous FBH size 2 3 4 5 6 7 8 7 5 4 3 3 2 b. Hole bottoms are checked for flatness and hole orientation is checked for perpendicularity to the block surface. c. When FBH size is plotted versus respective ultrasonic echo amplitude for a given equipment set-up, a straight line ± 2 dB should pass through the plotted points.

Privacy Statement
Press Release
Contact