UT probes for structural steel

[TTT]

I watched a technician test structural steel welds 8-20mm
thick with a 45deg then size defects with a 60deg
probe.
Would a 45deg be suitable for low wall thicknesses?

 

[AEF]

The questions I'd ask are; was the technician ASNT (or other) certified, does the company they worked for have qualified procedures, and were they following them? If the answer is no to any of the above, I'd question their results and have them do a performance test on test plates to prove their technique.