×
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

stainless steel cool down
3

stainless steel cool down

stainless steel cool down

(OP)
I have a piping system made out of stainless steel.  We use a cleaing method that heats the water running through the pipes to 200 degrees C.  After the cleaning is done we the temperature drops too 100 degrees C rapidly in 1 minute and I was wondering if there was anything I should worry about?

RE: stainless steel cool down

How good are your pipe supports?  Is there any thing in the design to allow for thermal expansion?
A 100' run of tubing will only change by about 1/8" with this temperature change.  It probably isn't a big deal unless your piping is very rigid.

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

RE: stainless steel cool down

You should check the water composition for chlorides and the oxygen content. At the given temperature, you should limit the chlorides to no more than 25 ppm or even less. Also, how do you cool the water down to 100 deg C, with treated cooling water in an exchanger? Same principle applies to prevent the SCC.
Cheers,

gr2vessels

RE: stainless steel cool down

I think you should be aware that differential thermal fatigue is a very distinct possibility if this procedure is done very often.  

How often is this procedure done?

How do you cool the system from 200 C?

RE: stainless steel cool down

(OP)
oh wow, i am sorry... the temperature change is in F not C.  The water never reaches boiling point.  

RE: stainless steel cool down

In addition to gr2's comments,  There is also a concern about external chloride stress cracking.  At 200F 300 series stainless will crack quickly.  If there are chlorides on either the inside or outside you could be in for some serious issues.

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

RE: stainless steel cool down

If the surface of the steel is free from pits and scratches and the welds are well dressed it is more than likely that steam containing up to, say, 50 ppm chloride could be used for cleaning without initiating SCC providing that the surface is rinsed thoroughly with low (<5 ppm) chloride water immediately after cleaning.

RE: stainless steel cool down

In order to affect the metallurgical properties, it would have to get a whole lot hotter- so you shouldn't have quenched-and-brittle type issues at least.

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