316L used in 98% sulfuric acid with chlorides

[Fiorellino]

Hi all,

I would like to know if 316L is suited for the 98% sulfuric acid with chlorides content from 500ppm to 1000ppm, will chloride ion still accelerate the pitting for S.S in 98% sulfuric acid? And what is the corrosion rate versus chloride concentration? many thanks.

 

[Unotec]

SS doesn't like chlorides. SS doesn't like sulfuric acid. You have the wrong material for the application

<<A good friend will bail you out of jail, but a true friend
will be sitting beside you saying ” Damn that was fun!” - Unknown>>

 

[EdStainless]

How hot?
98% sulfuric with a few thousand ppm Cl will work in 904 up to at least 30C. I don't know about hotter. Forget a lower Ni grade, they won't cut it.

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Plymouth Tube

 

[Fiorellino]

the max temperature is 40 deg, the operation temperature is 25 deg, 316L is suitable for the pure 98% sulfuric acid under 50 deg, I just want to know if the chlorides can accelerate the corrosion in this service, and what is the corrosion rate? thanks

 

[strider6]

Stainless Steel is suitable in concentrated Sulfuric Acid because it's in passive state. Chlorides will cause the Stainless Steel to be in a active state with following corrosion.
In my opinion, based also on the isocorrosion graph and table of Outokumpu linked below, Stainless Steel is not suitbale in your conditions.
As you can see in the graph for Sulfuric Acid + Chlorides Stainles Steel 316L (17-12-2.5 in the graph)is not included.
Sulfuric Acid Isocorrosion for Stainless Steel

http://www.outokumpu.com/applications/corrosion/image_viewer.asp?image=sulphuric1.jpg

Sulfuric Acid + Chlorides

http://www.outokumpu.com/applications/corrosion/image_viewer.asp?image=sulphuric3.jpg

hope this help u
S.


Corrosion Prevention & Corrosion Control

 

[Fiorellino]

Thank you Strider,

I agree with you that[SO4]2- will increase the passivity of S.S, while Chloride will accelerate the corrosion, my understanding is there should be a limitation, I mean when there are a lot of [SO4]2-, does chloride still can effect the corrosion?

I had the graph of Outokumpu, I thought they did't have the actual data for this service condition, so they didn't show it on the graph. hope my understanding is not wrong.

thanks

 

[strider6]

i don't think that the reason is that they don't ahve data. If you make a comparison between the graphs you'll see how the corrosion resistance of 904L alloy decrease when chlorides are added. 904L is a super austenitic steel that has much higher resistance vs 316L.

S.

Corrosion Prevention & Corrosion Control

 

[EdStainless]

You will also notice that the higher Mo grades don't do as well as 904 which is medium Mo and high Ni. It has to so with passive film stability.

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Plymouth Tube