Pitting Corrosion

[ihamed]

Hi. i just wanted to get an explanation on why is the 7.5 % HCL worse in terms of pitting corrosion compared to 10% HCL

 

[strider6]

Ihamed,

It's not easy to give you a reply with so many data. Corrosion is dependent on many factors. It will be necesasry to know what type of material are you concerned about, operating Temperature, environment, fluid and so on to tell something.

Regards

Vict

Corrosion & Materials Engineer

http://xoomer.alice.it/corrosion

 

[ihamed]

thanks for replying, i just wanted a general explanation. maybe at 10 % HCL concentartion the hydraogen ion at the cathode would form a barrier that might inhibit corrosion. can this be possible?

 

[strider6]

I don't see any reasons for a similar behaviour. But are you referring to a lab test result, publications, book or is just something you've heard?

regards

Vitt

http://xoomer.alice.it/corrosion

http://corrosionist.blogspot.com

 

[ihamed]

Hi, it was actually an observasion that we had on our carbon steel pipe we use. so i was looking for an explanation?, anyhow what could be the effect of concentration of acid on pitting corrosion. are they directly propotional?

 

[EdStainless]

I don't see any reason why these two concentrations would behave differently from each other. They are so close.
Unless there are factors such as impurities and/or temperature I would suspect that it may be related to minor differences in the materials.

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Rust never sleeps
Neither should your protection

http://www.trent-tube.com/contact/Tech_Assist.cfm

 

[stanweld]

I saw the same type of response when performing corrosion testing. At the higher acid concentrations general wastage was observed. At 7.0% and 3.5% the corrosion mechanism began to change from general wastage to pitting.

 

[strider6]

Maybe is something true but related to a very specific, material/environments/operating conditions, and not a general consideration applicable to HCL.

Vitt

http://xoomer.alice.it/corrosion

http://corrosionist.blogspot.com