×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Contact US

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!

*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

347LN temperature limit

347LN temperature limit

347LN temperature limit

(OP)
Dear all
I was given the information that the use of stainless steel 347LN should remain limited to temperatures below 450°C - for corrosion reasons -

Unfortunately, I cannot identify the type of (thermal ?) damage that may be so harmful that it would restrict the use of SS 347LN to temperature below 450°C, whereas other similar stainless steels (ex: 316, 304, 321, 347, ...) could be used at temperature above 450°C.

What's the problem with operating SS 347LN above 450°C ?

Thanks

Regards

RE: 347LN temperature limit

I haven't seen S34751 in many years.
The real question is how was it heat treated?
Was it annealed or stabilized?
If stabilized you should be good to the same temps as 321 or 347.
You will begin forming carbides and nitrides above 450C, but that is what the Nb is for.
The problem is that in service if you are above 450C but below 600-650C you are likely to sensitize.
If your service is above 650C it should stabilize in service.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

RE: 347LN temperature limit

(OP)
hello
I spoke to Sumitomo that developped the SS 347LN and they confirmed that there is no reason why SS 347LN should be limited to low temperature service < 450°C.
It seems our mistake came from a typo 540°C vs. 450°C. indeed, 540°C (or 1000F) is ASME max temperature limit for austenitic SS with less than 0.04% carbon, and SS 347LN has less than 0.04% carbon...
sensitization is usually not a problem when no electrolyte is present.
thanks Ed for your answer.
regards

RE: 347LN temperature limit

Quote (Chumpes)

sensitization is usually not a problem when no electrolyte is present.

That's my reasoning for most cases as well, e.g. when it comes to material selection in services around 600°C.
The 'default' stainless steels may quite often be suitable, but they only dont meet the carbon content requirement.
Under normal operating conditions, electrolytes arent present. During shutdown, or after, condensation may occur.

Is that the general consensus, anyone to concur or have a different point of view on that?

Huub
- You never get what you expect, you only get what you inspect.

RE: 347LN temperature limit

'Normal' SS grades are often used in hot dry applications (gas to gas exchangers) where they sensitize.
But woe to the people that get sloppy dry gas purging or with wash out.
With good practices you can get away with this easily.
In some alloys (higher Ni & Mo) you can also form other detrimental secondary phases which can significantly lower the toughness of the material.
Thermal shock can then become an issue.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

RE: 347LN temperature limit

Sorry I’m not native English so I didn’t quite catch what you meant with

Quote (EdStainless)

But woe to the people that get sloppy dry gas purging or with wash out.
With good practices you can get away with this easily.

Huub
- You never get what you expect, you only get what you inspect.

RE: 347LN temperature limit

If the tubes do sensitize (as is highly likely) and they ever get wet you can get IGA.
I have seen this happen to units during outage.
Either process water is left standing in them or they get wet during the outage.
Either can cause problems.
It is common to wash with very clean water and then blow the system out with dry air.
A lot of this depends on what kinds of residue or fouling might be on the tubes.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

RE: 347LN temperature limit

Thanks for the explanation Ed

Huub
- You never get what you expect, you only get what you inspect.

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! Already a Member? Login


Resources

Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close