Welding CS, LTCS to SS 316L

[ukmet]

We need to weld A-106Gr.B and A-333 Gr f with A-320 TP 316L pipe. The filler wire to be used will be of 309L? If yes following are my questions?

1. 309L is for dissimilar metals but isn't 316L superior that 309L
2. Quantity of Mo in 309L is very low compared that to 316L. Is it ok to weld? It will not be an issue?

 

[metengr]

If this is for moderate to low temperature service, the dissimilar metal weld (DMW) metal should be 309L. The corrosion resistance of the DMW will be between carbon (low alloy) and 316L stainless steel.

 

[EdStainless]

You are not using 309 for corrosion resistance (obviously not a concern since you have CS in the system) but for its ability to allow dissimilar welds without excessive hardness or risk of cracking.

If the weld was 316-316 or 316 to a higher alloy product then 309 would not be a suitable choice for filler.

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P.E. Metallurgy, Plymouth Tube