UT thickness on Vinyl Ester lined tanks

[dlmann]

Have a 0.375 in., shell and head, tank with internal Flake Glass Reinforced Vinyl Ester coating system (3 coats totaling 50 mils)and coated externally with Semcrete No. 954 Epoxy (12 mils).
1. Is it possible that when we take thickness measurements from the outside of the tank that the sound wave propagates throught the Vinyl Ester coating and reflects back and is included in our thickness readings? We are using a simple StresTel T-Mike E thickness gage. We are getting readings in the mid 0.400's.
2. Do we have to much tank for our little thickness gage? 3. Do we need to invest in a gage with B-Scan or A-scan capabilities to separate the differ signals?

 

[edellison]

most all of my experience has been with the KB DMS and DMS+, with that said from what i've seen you would never pick up the lining material if the meter is set up correctly. i can't begin to think of doing UT testing without A scan on the meter, but i know lot of people do it.

 

[ledon]

I agree with edellison. There is no accurate way of verifying your sound path without and A scan. The KB DMS 2 is a good machine to use, but if you like Stresstel the the T-Scope would be a good alternative, and a little cheaper.