ASTM B366-N08367 as alternative for UNS S31254 2

[FIF99]

Hi,

One of our suppliers proposed ASTM B366-UNS N08367 as an alternative material for SMO UNS S31254. Although these materials are reasonable similar we do not know if any concerns should be highlighted regarding weldability.

The Nickel content of ASTM B366-UNS N08367 is about 6% higher (for N08367 24% Ni and for S31254 18.5% Ni).

Anyone familiar with welding these materials together? Vendor states that subject materials are used frequently through each other.

Thanks in advance for any help.

Regards,
FKE

 

[metengr]

Yes, we are under the design phase for building an FGD (fluidized gas desulpherization) system and I had to evaluate material options for the absorber vessel, including both alloys mentioned above. The N08367 is AL-6XN, and the S31254 is the 254 SMO. The service environment for these alloys will be high chloride content (~20,000 ppm ) and a pH of 5. Your service conditions may not be as aggressive.

Regarding welding - both are readily weldable, no preheat and interpass temperatures at or below 300 deg F. Filler metal selection depends on service conditions (which you did not mention) For FGD service requirements, the filler metal for welding needs to be over matched in molybdenum content. Molybdenum tends to segregate in weld deposits, which effects corrosion resistance. Typically, for AL-6XN we would specify an ERNiCrMo-3 or 10 to assure adequate molybdenum content in the weld deposit.


For 254 SMO, the same would apply for an over matched filler metal using ERNiCrMo-3 or 10.

I would suggest you visit the two web sites below for further technical information;

http://www.outokumpu.com/applications/documents/start.asp

(254 SMO)

http://www.alleghenyludlum.com/ludlum/pages/products/xq/asp/G.16/qx/productLine.html

(AL-6XN)

 

[FIF99]

Hi Metengr,

Thanks a lot for your message!

Do you know if measurements, or special considerations, should be taken for welding SMO S31254 against N08367?

Our pipe class for seawater (ASME Class 150#, Press. 19 bar and Temp 60°C) is fully based on S31254. Vendor quotes N08367 as an alternative for some components only.

Thanks in advance.

Regards,
FKE

 

[EdStainless]

Don't forget the other options also, N08925 (1925hmo from VDM) and N08926 (25-6Mo from Special Metals).

What filler are you looking at using for these welds? If you are using a 6%Mo filler then make sure that it has higher Ni and Mo than either of the alloys that you are joining.
In many application I see people using Ni-Cr-Mo filler (C22, 59, 686)to assure good corrosion resitance of the welds.

= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection

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

 

[SJones]

Look at NORSOK M-630 and M-601.

http://www.standard.no/pronorm-3/data/f/0/05/60/5_10704_0/M-601.pdf

Steve Jones
Materials & Corrosion Engineer

http://www.pdo.co.om/pdo/