Welding 3" Thick 347 SS to Carbon Steel 3

[iam42]

Hi Guys,

I have a job coming up that requires us to weld 3" thick SA182-347 to SA106 Gr. C Pipe. I am no metallurgist but I have read enough in here to scare me a little with regards to Re-Heat Cracking on thick sections. I am not sure if this is a major factor but the design temp for this joint is 550°F

My Plan at the moment is to butter the CS weld bevel with ERNiCr-3 and then PWHT the CS pipe. I then plan to weld the joint with ER347 in a similar manner to a standard 316 or 304 joint.

Is my plan flawed and doomed to failure?

If so, can some kind sole please suggest a better approach.

Many Thanks

 

[EdStainless]

I don't see hat 309 would hurt.
If this was something that saw rapid temperature cycling then I might worry (difference in thermal expansion) .
Watch the temps and you will be fine.

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P.E. Metallurgy, Plymouth Tube

 

[iam42]

Thanks Ed,

Your help is appreciated.

 

[weldstan]

309 is fine with the caveats from metengr and Ed and only one PWHT. Because of the coefficient of expansion differential, effective stress relief will not be incurred by the possible Code mandated PWHT.