SS316 tank - welding with309L Mo 1

[starflex]

Hi there,

I have a SS tank, made of 316L, containing acidic slurry, which is supported externally by a mild steel structure. The tank is welded to the mild steel support using 309L Mo consumable.

When the side wall of the tank join the base of the tank (again, both made of SS 316l), the tank joins also the mild steel support ring. See picture for explanation: grey is SS, reddish is carbon steel.

There is one weld (the yellow/black one) that theoretically joins only SS to SS: Can I use the 309L-Mo (2.7%Mo) for that weld? I am comfortable in using the 309L Mo for the other two (black and white ones) as they join CS with SS).

Although the 309L material would not be recommended for that acidic service (because of the low content of Mo), I would suspect that a 309 consumable with 2.7% Mo would be suitable.

Your call ?

Thanks!

 

[pradipgoswami]

What's the media? What type of acidic slurry the tank will contain? Appreciate you could provide those details.
Thanks.

Pradip Goswami,P.Eng.IWE
Welding & Metallurgical Specialist
Ontario,Canada.
ca.linkedin.com/pub/pradip-goswami/5/985/299
All provided answer are personal opinions or personal judgements only. It's not connected with any employers by any means.

 

[metengr]

Why use the 309L-Mo for this weld? Use the 316L filler metal or if you worry about contact with the CS at the root, use 309L-Mo for the first pass and fill using 316L filler metal.

 

[starflex]

Hi there
Thank you for your inputs.

The media is acidic slurry at PH5-temperature between 30 and 40 Celsius; at this stage I do not have any other information unfortunately.

I honestly do not know why the client wants to use 309L Mo; I guess it was just a question about the compatibility of the materials. All the communications have bee through email and I did not have any chance to investigate deeply. Will try to receive some more detail on that if available, but will definitely point out the 309L-Mo for the root and 316L for filling.