Corrosivity to SS316L with Sulfuric Acid

SS316L is supposed to handle sulphuric acid upto quite a bit concentration well. However the welds are another matter.

But why don't you use pickling solutions?

No one will give you an answer with a question posed like that.

Depends on what are you removing,

Contact you chemical supplier....if you have one, if not...try this.

http://www.ecolab.com/

They are pricey, but they know.

phoenix911

Hello All,

We are trying to remove calcium scale/deposit from the vessel at ambient temp. The concern was whether it will have any corrosion on the body of the vessel.

Also interested to know any precaution to be taken.

As SB stated, in general 316SS should handle that concentration just fine. but you will need to be aware of ANY other components (gaskets, seals, O-rings, nuts/bolts, sensors, floats, ball valves etc etc) or weld seams which are not 316SS. It is also good to know what you are trying to clean from the SS.

Thanks for the reply.

It is Calcium deposit that has to be removed from the vessel.

SS316L is cofortable only in acidic but oxidising environment say not in HCl (a riducing character acid) and hence so far as you maintain oxidizing environment with this concentration of acid, you should not face any problem at ambient temperature.

What temperature levels are you targeting? If ambient, it should be fine for the vessel, but as others note you need to look at the gaskets, welds and seals.

It will be ambient temp. Thanks for the answer.

Removing calcium scale with sulfuric acid sounds like a "no-win" situation to me. Calcium in the presence of the sulfates of the acid will form a relatively difficult CaSO4 scale which is difficult to dissolve. You may end up in a worse condition than you started with! I suggest that you determine the existing calcium scale composition and get some help to determine the best cleaning agent to dissolve that contamination.

Yes, agreed. I am waiting for the scale analysis.

try it

http://www.dow.com/versene/app/scale/rem.htm

Thanks a lot for so many links...!!

Acetic acid would be probably a good choice.But remember: Do not scratch the surface of the stainless steel while it is immersed in acid.It will eat right through.SS relies on Chromium Oxide to protect it from corrosion.If the film is removed, and it is immersed in acid before it "heals" it will have a very high corrosion rate.

I have seen 8 inch ss pipes with holes eaten thru by acid, because a loose piece (nut) of machinery bounced around inside it while it contained acid.

Good Luck

EZStreet

PS:

I forgot to answer your original question:The corrosion rate for Sulphuric acid on 316 SS is greater than .020" per year.Acetic acid is less than .005" per year.

EZStreet