applying hydrofluoric acid to large stainless steel tanks

[grizzlyone]

We have a customer with a one time requirement to apply a 3-5% hydrofluoric acid solution to the interior walls of four large stainless steel tanks. The solution is to be supplied to a rotating nozzle using a 100 gpm, 135 psi centrifugal pump. We are having a very difficult time to source this equipment since most suppliers check their standard compatibility charts and then say they can’t recommend their product. Exotic or special built equipment is out of budget since this is a one time application. The duty cycle calls for 40 minutes of pumping the dilute solution followed by a copious throughput of neutralizing alkaline. Solution temperatures will not exceed 50 degrees Fahrenheit. This would be done 4 times and the job is complete. In terms of “opinion only”, is it possible to do this short run job with standard components of bronze and stainless steel?

 

[EdStainless]

I would consider pumping with a jet pump or eductor. We use eductors to pump hot (60C) mixture of 20% nitric acid and 4% HF. We use steam and/or air as the motive fluid.
You actually could use high alloy stainless steel for this, and destroy the equipment. The pickling time for alloys like AL-6XN is a couple of hours. It would probably hold up long enough.

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[grizzlyone]

Thankyou EdStainless for the excellent suggestion. We will use an inline eductor to introduce HF solution just before the nozzles. Eliminates pump damage. Nozzles are consumable. Best regards.