653 Inspectors - UT measurements thru exterior coating?

[Blazer406]

Looking at a new UT Thickness meter. I see some advertised as having the capability to go thru the paint. We have mostly done our inspections by wire wheel buffing the paint off down to bare metal and taking our readings from there. The ability to not have to buff off the paint (and re-apply paint after we are through) to take the readings would be a time and money saver.

What do you guys do?

 

[chicopee]

There are meters that will measure paint thicknesses. DOT inspectors use them when measuring paint thicknesses on girders.
I normally measure thicknesses after wire brushing and hand sanding to smooth out painted surfaces but I will not totally remove the paint layer from the steel surface .
Where I may leave exposed steel surfaces is when the paint and primer on a tank are flacking off. Then I'll tell the owner to recoat the tank when the weather allows it.

 

[Duwe6]

Please see the thread below: good meters w/single-element 'ducers work, cheap meters with dual-element 'ducers don't work thru paint.

http://www.eng-tips.com/viewthread.cfm?qid=292213&page=1

 

[darthsoilsguy2]

We use equipment that eliminates the paint by measuring peak-to-peak. we also take off the coat for a double-check reference point at least once a tank, when there is a significant jump in base metal thickness between adjacent plates, or when our eyebrows raise.

Occasionally, i find a client who has testing records that show the thickness to be greater (usually 30-50 mils extra of fast steel, not slow paint)than when it was built b/c the UTT was done with a basic thickness gauge. Other times i come across tanks where the old test spot didn't get recoated.