[lucas]

IRIS is basically UT. It gives you thickness readings of the tube. The only downside is the tube internals needs good cleaning for IRIS to give good readings. For Diesel and Kerosene, cleaning shouldn’t be a problem.
For purposes of scanning, MFL (magnetic flux leakage) would be more appropriate. It however does not give thickness readings but only a percentage of wall loss. It is a faster scanning tool, though