The Russell Bracelet Probe may be used on insulated vessels and tanks too.
Finding the highly corroded areas (salmon coloured areas) on the tank pictured below would be a challenge.

The following photos show the BP in action:

On corrugated aluminum cladding on the bottom of an insulated vessel.

... and on a vertical vessel.
For more information on the CUI Bracelet Probe please go to info@russelltech.com