Welding of clad vessels 1

[brandonb73]

I need some advice on welding a clad vessel. The vessel in question is an autoclave constructed of SA-265 (SA-285C) with a crack in the shell.

My question is regarding the Weld Procedure used. Currently we plan to use a P1 to P43 weld procedure with Inconel 92 filler metal. The whole crack will welded with this procedure. Is this an acceptable method or should we be welding the SA-285C base metal with a P1 to P1 procedure and then replacing the cladding with an overlay procedure?

 

[DVWE]

Is the reason for the use of Inco 92 to omit PWHT?

 

[brandonb73]

No, the Inconel 92 was selected becuase it is used for joining carbon steel to nickel based alloys. There was no PWHT performed on this vessel.

 

[DVWE]

The Inco should work just fine, but it's an expensive alternative isn't it? Typically, that is used where PWHT isn't practical due to location or other service restrictions.

If it was up to me, I would do it as you suggested in the latter. If the autoclave has substantial thermal cycles, I would be more inclined to match the weld metal with the base metal. Then overlay the finished weld as you suggested.

 

[SJones]

The cause of the cracking has been established and is expected not to occur again? The crack will be removed and confirmed as removed before welding?

Steve Jones
Materials & Corrosion Engineer

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