Welding CS to Cs with ER80S-D2 3

[rmillercwi]

Ive been tasked with reviewing a boiler repair performed several years ago by a well established vendor.

Replacing several boiler tubes in several different boiler sections. Header/tube material garden variety 10" sch 120 SA 106 B/ 2" 120mw SA 178A. Nothing special about this configuration.

For the tube to header welds, I would have expected to see a GTAW procedure using ER70S-2 and maybe an additional/combination SMAW procedure using 7018

In this case, all the root welding was done with ER80S-D2/7018 Nothing particularly wrong with it...just havent seen it done before.

Why choose the ER80S-D2 over ER70S-2? It would seem the Moly addition would decrease weldability in an allready limited access configuration (and bring weld preheat into the job)

 

[weldstan]

ER80S-D2 would provide additional high temp strength in the weld metal above 650F, but at a cost of some temper embrittlment above 750F. We would have used ER70S-6 for this application in lieu of ER70S-2. Many Contractors/Suppliers use ER80S-D2 in lieu of the simple C-1/2 Mo filler because of it being more readily available.

 

[DVWE]

I agree with what weldstan has posted above, and I'd also like to add that the small addition of Mo does not decrease weldability, nor does it add the requirement to preheat. Preheat is recommended, but not required. If the WPS was qualified with preheat, then of course it is mandatory.

Have a read of SFA-5.28, Annex A, A7.11 for a pretty good description of this electrode.

The devil is in the details; she also wears prada.

 

Ditto to both answers.
ER80S-D2 is perfectly suitable for the task, with no decrease in weldability. You could even safely weld over existing D2 deposits with ER70S-X carbon steel filler.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[rmillercwi]

Thanks guys...

 

[gtaw]

Do they have a qualified WPS? Without looking, I suspect the -D2 might affect the A number if the original WPS was qualified using an E70S-X filler metal.

Al

Best regards - Al

 

gtaw,
I don't recommend that, I'm just saying it would be technically doable. There are obvious complications for a WPS in mixing classifications and A-numbers.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."