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Chemical compatibility of stainless steel

I have a tank made of material AL6XN, which is probably stainless steel. Water with Fluoride content of 10,000 ppm and HF at 50% flows through it at 750~900 psi.

I want to know whether the tank will be able to withstand this without getting corroded and waht are the other disadvantages associated with it.

Karunesh Sharma
enclosures - Delhi, India
2005

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I am not familiar with your alloy. Also, you did not mention the temperature or the thickness of the tank wall.
I would be amazed if the tank lasted one year. At that pressure, any pinhole is going to put out a spray. If it happens when you have 50% HF going thru it, You will have a serious risk to your people at quite a distance from the tank.

James Watts
- Navarre, Florida
2005

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Totally agree with James Watt: very dangerous. A rough guess is that AL-6XN (UNS designation N08367) will corrode at 40 mm/year. The described usage may be illegal; consult a licensed pressure vessel engineer. AL-6XN contains about 24% Ni, 21% Cr & 6.5% Mo, so has resale value.

Nickel alloys 400 (N04400), C-276 (N10276) and possibly 600 (N06600) may be suitable. Purging the HF solution with oxygen-free nitrogen reduces corrosion with these alloys.

The only thing more expensive than good engineering is bad (or no) engineering.

Ken Vlach [deceased]
- Goleta, California
Finishing.com honored Ken for his countless carefully researched responses. He passed away May 14, 2015.
Rest in peace, Ken. Thank you for your hard work which the finishing world, and we at finishing.com, continue to benefit from.
2005

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2005

Hi Karmesh,

Well, James sure HIT it on the HEAD ... it seemed to me that surely that was a misprint ... 900 psi in a tank full of lovely HF. ?

Personally, I wouldn't like to be anywhere near that damned thing. What purpose does that supposed pressure serve?

And the tank would have to be made of armour plating for that pressure.

The other disadvantage would be that if it leaked or blew up, would you qualify for any insurance? HF is a frightening acid, one drop on you can cause damage.

Freeman Newton [deceased]
(It is our sad duty to advise that Freeman passed away
April 21, 2012. R.I.P. old friend).