Ester corrosion of carbon steel

[dsnyder2]

I have a vessel encased in ASTM A-516 Grd 60 carbon steel. If I were to pump an Ester through it (at moderate speeds and temperature) and also pump filtered air (no moisture removed), should i expect significant corrosion within a reasonable timeframe?

 

[dsnyder2]

Im sorry, I wasnt too specific, the Ester is a sulfonic acid ester

 

[strider6]

dsnyder2

Looking on NACE Corsur i've found, sulfonic acids corrosion data for Steels, Carbon/ Low Alloy. For concentration in the range of 5 – 35 % and temperature 25 – 75 °F the corrosion rate is >50 mpy.
This is just an indication, in your case it depends on the operating conditions and fluid concentration. The ester with humidity can give an acid in you conditions?


Strider

http://www.corrosionist.com

 

[dsnyder2]

50 mpy does seem quite high. the humidity in the air appears to negatively affect the corrosion, though I have not tested exactly why. I was told when the part was purchased that it would hold up fine, but it is showing signs of failure after just a few months. The sulfonic acid concentration is in the range of 5-35%, but temperatures do exceed 75F. I know the carbon steel performs more poorly at temperatures pushing 50C, and the continuous, moderate pressured flow of the acid will speed the process. It suprises me that the acid is able to eat through the carburized layer of the A516-60 steel casing so quickly, though. Should it not hold up better?

 

[kclim]

The carburised layer typically has better mechanical properties (hardness, fatigue strength) than the bulk metal, but don't count on it for better corrosion resistance. If anything, the addition of impurities into steel (i.e. carbon from carburising process) would be expected to increase corrosion susceptibility.

In general, carbon steel is not a good idea for acid duty with no inhibitor. While uniform corrosion rates might be accounted for using a corrosion allowance, localised corrosion can lead to rapid perforation of your vessel.

 

[strider6]

Your vessel is made in Carbon Steel A-516, i don't understand what you mean by carburized layer and why it should protect the material from corrosion. It's something that was told you by the supplier?

S.

http://www.corrosionist.com

 

[dsnyder2]

I think ive found what i need thank you. The humidity of the air was much higher than it was supposed to be due to a defective part, which should account for the increase in corrosion. Is there a free database where I could reference these corrosion rates? I need to reference stainless steel AISI 304 and 316, and carbon steel ASTM A516, corrosion rates for sulfonic acid

 

[unclesyd]

Everything we have that touches Sulfonic Acid is made from 316L SS.

 

[strider6]

You can find free database for corrosion of Stainless Steel on:

http://www.outokumpu.com/applications/documents/start.asp

and click on corrosion handbook, i've not checked but probably there is also the sulfonic acid.
Regarding corrosion rate for carbon steel i've never found a free database, the only data that i've found are on the Corsur Database of NACE that you can access on the Knovel website. Probably unclesyd is right and you have to select a more resistant materials like SS 316L.

S.

http://www.corrosionist.com

 

[dsnyder2]

exactly what Im looking for thanks. It does not have sulfonic acid, maybe because different R-values for sulfonic chain change corrosion rates...