Suitable Material for Fluosilicic acid

[mthakur]

Hi,
We have a Den Exit fan installed in super phosphate plant, the impeller is made in SANICRO 28 and has a limited life due to very aggresive corrosive medium. It contains 1% Fluosilicic acid, and approx 0.2% hydrofluoric acid. Air temperature would be in the range of 40 - 55C. Can anyone suggest what is the best material for this application for fabricated impeller which uses 6mm thick plates.
There are small amount of silica in the medium which causes erosion as well in leading edge of the blades.
regards

regards

 

[strider6]

here you can find corrosion data, isocorrosion for Fluosilicic acid and hydrofluoric acid. is not easy to define what happens when the two acids are mixed.

Fluosilicic acid

http://www.outokumpu.com/applications/corrosion/view_details.asp?name=FL03

http://www.outokumpu.com/applications/corrosion/image_viewer.asp?image=fluosilicic.jpg

hydrofluoric

http://www.outokumpu.com/applications/corrosion/image_viewer.asp?image=hydrofluoric.jpg

http://www.outokumpu.com/applications/corrosion/view_details.asp?name=HY12

654 smo seems a good choice..

S

Corrosion Prevention & Corrosion Control

 

[EdStainless]

I can't see 654 being any better than S-28. I really think that it is time to seriously look at the Ni based alloys.

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