Ultrasonic Inspection from the internal insulated vessel 1

[MadieKerang]

Hi all,

Does anybody have a good or bad experience using ultrasonic measurement wall thickness from inside the insulated vessel ( in case we cannot strip of the insulation due to short shutdown duration and limited manpower). Is it okay from inspection engineering view and is the result acceptable.

Please advise.

Thanks

 

[unclesyd]

We do it all the time on insulated SS and CS vessels and tanks. The only problem I've seen is the transducer size on the smaller vessels, which can easily be overcome by an experienced NDT Technician.

 

[ndeguy]

unclesyd is right - its much more diffcult to radius a transducer to match a concave surface than for a convex surface and the larger the transducer its evenmore difficult. If you radius the wedge at all then you will have the problem of calibration unless you have a similar curvature calibration block.

Intrinsic safety might also be an issue you'll have to deal with -there are intrinsically safe ultrasonic thickness gauges on the market.

As far as the ultrasonic measurement goes even insulating material adhering tightly to the OD of the vessel will still allow a good measurement of the wall thickness because of the big variation between the acoutic impedances of the metal and the insulation.

 

[MadieKerang]

Gents,

Really appreciate that great answers, looks like i have to start from buying a small probe.

Thanks all

 

[unclesyd]

As with any UT inspection the surface needs to be clean and as smooth as possible, so don't be afraid to use an air grinder.

Once you locate your area of interest you might want to look at Access Plugs like the ones from Access Plug Flange. We have these on nearly all our insulated tanks that are witnessing corrosion

http://www.inspectionplug.com/