×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

CSCC of stainless steel in HCl

CSCC of stainless steel in HCl

CSCC of stainless steel in HCl

(OP)
Greetings,

   Are austenitic stainless steels subject to CSCC in Hydrochloric acid that is not contaminated with chlorides coming from alternate sources than the acid itself (like NaCl)?  My thoughts were that the acid in water should disassociate into hydronium ions and chloride ions the latter of which could lead to SCC issues.  However, since CSCC only happens within a given range of electrochemical potential, I figured it may be possible that severe general corrosion may be the only result of placing austentic SS in HCl.

Thanks,
Bob    

 

RE: CSCC of stainless steel in HCl

Boiling HCl (18%) is one of the few environments that will cause general corrosion on common stainless grades.
You do not get CSCC in HCl service, but tiny amounts of residual acid can cause significant problems later.
Remember, not only is the HCl disassociating, but water also.  The chemistry is rather complicated.

= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection
http://www.trent-tube.com/contact/Tech_Assist.cfm

RE: CSCC of stainless steel in HCl

(OP)
Thanks EdStainless,

  Thanks a ton for your help.  What happens to the stainless if you are at a temperature below the boiling point at 18% concentration such as 175F?  Do you get severe pitting or just general corrosion?  Also, what happens at stronger concentrations like 35% just below the boiling point.  All my references simply state to never use common grade austenitic stainless steels in HCL but they never mention what actually happens by dicussing pitting versus general corrosion versus SCC.  

Thanks,
bob

RE: CSCC of stainless steel in HCl

With 304, at any concentration and temperature you get general corrosion.  At 18% and boiling the rate is roughly 0.030" - 0.090" per hour.
As you move to higher alloy grades the attack is still general, but the surface get rougher.  It is almost like continuous pitting.
On high alloy grades like superaustenitic or superferritic you don't get much general attack, but you can get severe pitting.
I know that the books warn of CSCC, but I have only seen it in hot HCl vapor applications.

= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection
http://www.trent-tube.com/contact/Tech_Assist.cfm

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources