Double Wall Tank Testing

[cwigg66]

Anyone have any experience doing the integrity testing for a double wall, horizontal UL 142 tank (10K-20K range)? For single wall tanks, ultrasonic testing has worked well for us in the past. However, non-destrcutive testing of a double wall tank seems a bit tricky. Anyone with experience wanna enlighten me? Thanks!

Chris

 

[stookeyfpe]

It's not tricky but you have to perform the test correctly. The primary tank must be pressurized to the same pressure you will apply to test the interstitial space. If you don't do this the primary tank can collapse.

Are these tanks in service or new? If they are in service you have the complication that the IFC does not allow the use of air for pressure testing in existing systems. The concern is the potential for adiabatic compression of any remnant hydrocarbons.

The other important element is to ensure that your pressure regulators are calibrated and that your test pressures do not exceed those specified in either the tank's listing nameplate or by the manufacturer.