FN Range for Type 347 1

[PAN]

In weld deposit overlay, our specification shows limit FN 5 to FN 8 for Type 347. The limit shall be confirmed prior to PWHT.
-Is this practical in the fabrication industry to control in only 3 range as above requirement?
- What should be the specific concerns for Type 347?


The fabricators informed that they need at lest 5 range to control the ferrite number (FN 3 to FN 8) for Type 347.

I found the related thread in thread725-34135 . However, this is not answer my question about the FN range for Type 347. Please comment.

 

[metengr]

PAN;
According to my reference material to prevent weld metal liquation cracking in 347, the minimum ferrite number is 6.
So, I would use a range of 6-10. The source of this information is "Welding Metallurgy and Weldability of Stainless Steel" by Lippold and Kotecki.

 

[ijzer]

FN5 to FN8 range is a to small band for practical work.

 

[PAN]

metengr & ijzer,
Thanks for the comment. I just check API RP 582. The acceptable range for Type 347 is FN 5 to FN 11.

I understand that the proposal FN 5 to FN 10 should be acceptable.

Please advise me if you have additional comment.