stainless steel and fluoboric acid 1

[sport8974]

Is 316L suitable for overhead piping for brief low concentrations of steam distilled fluoboric acid?

 

[NickE]

What is fluoboric acid?

 

[sport8974]

HBF4, borofluoric acid, hydrofluoboric acid

 

[NickE]

This is proabalby the completely wrong way to go about this, but what the heck I'll try any way.

316 is listed (by the nickel development institute) as ok for boric acid at all temps in my chart. (20C->100C)

316 is listed (same source) as Not Recommended for Hydrofluoric acid at any temp.

so my SWAG (see this thread for the definition of SWAG thread1010-120615) is that I wouldn't use it.

nick

 

[StoneCold]

sport8974
One of the MSDS's that popped up when I ran a search on hydrofluboric acid said that the product decomposed to HF and BF3 before reaching it's normal boiling point. The HF will eat into the stainless in a big hurry and BF3 is a pretty nasty gas that will be leaking out of the holes. 316L is a bad choice for this project. You need a metal that can withstand HF. I am not sure what metal that is off the top of my head but 316L is not the right choice.

Regards
StoneCold

 

[unclesyd]

We use HBF4 in plating, mainly lead but experimentally many others.
We never used HBF4 or it's salts in metal equipment.
We received most of the chemical in poly drums and our tanks were polyethylene and polypropylene. The pumps were Teflon or Tefzel lined. The heaters and coolers were the Teflon spaghetti type. We had an induced vent system over the tanks.
We used a lot of Kynar and polypropylene piping.

Here is source of Kynar piping.

http://www.fabtechinc.com/table01.html

If not proprietary information what is the MOC of the distillation equipment?

 

[rorschach]

Some high nickel alloys can withstand short exposures to HF, Inconel 718 625 and 725 are all used in downhole applications where the wells are treated with strong HCL and HF, but plastics strike me as much cheaper if they can operate at the temp and pressures required.