Keeping it clean. (ask roy).

Q in what manner can you avoid long-life fatigue failures caused by means of dirty steel?
A stores can use any standard puke-echo ultrasonic equipment to ordeal for dirty steel, if they do the following:
* make secure the instrument produces a full-screen reverberation signal from a 0.047-in.-diameter, flat-bottom aperture with its sensitivity set at 10% of maximum (as in the trial block shown).
* Check that the vertical linearity is [+ or -] 5% for signals to 90 [degrees] of full-screen height.
* plant the test frequency at 225 MHz
* Use a transducer that's 075 in. in diameter and made of