How to joining CRA pipe to CRA pipe? ( Claded incoloy 825, thick 5mm and base material thick 12.7mm) 2

[taliban999]

Hello All

When access from both sides are not possible, like welding clad pipe to clad pipe, generally the full joint is welded with the high alloy. (Clad pipe is CS(ASTM A234 WPB) + Incoloy 825). In this case Er Ni CR Mo-3 and E NiCrMo-3 is used. This has been my experience.

Now a contractor is suggesting to use the following weld sequence(And is willing to support with a PQRT)

1) 5 mm incoloy will be welded with Er NiCrMo-3
2) Next pass with E309, maybe 2 layers
4) Complete the joint with 7018.
A) These ways are cheaper than my ways. But can it be done?
B) Is there any documentation specifically on this CRA pipe welding?
Thank you for answering me.

 

[EdStainless]

I have seen this done, but with the first two passes being high alloy and then transitioning to 309/CS.
If you do cross sections of the weld coupons and are satisfied with the high alloy penetration and fusion then it should be good.

 

[taliban999]

I have seen this done, but with the first two passes being high alloy and then transitioning to 309/CS.
If you do cross sections of the weld coupons and are satisfied with the high alloy penetration and fusion then it should be good.

It is argued that the use of e309 and 7018 should only be done if welding from both sides is possible.
Will weld CS layer first with 7018 then weld e309 and finish by welding incoloy 825 layer so i'm a little confused

 

[kingnero]

Not too sure about the filler metal.
A PQR only says so much. Nothing about the fitness for purpose (corrosion resistance, working temperature and creep resistance, ...).
Other than that, no remarks about the working procedure. No problem transitioning to 309 and CS, as Ed says. Be careful about the heat (interpass temp, ...). I don't know the ASTM materials, but if the carbon steel has an elevated carbon equivalent, (chromium alloyed?), you'll want a minimum temperature during welding, and baked or vac packed rods.

 

[taliban999]

Not too sure about the filler metal.
A PQR only says so much. Nothing about the fitness for purpose (corrosion resistance, working temperature and creep resistance, ...).
Other than that, no remarks about the working procedure. No problem transitioning to 309 and CS, as Ed says. Be careful about the heat (interpass temp, ...). I don't know the ASTM materials, but if the carbon steel has an elevated carbon equivalent, (chromium alloyed?), you'll want a minimum temperature during welding, and baked or vac packed rods.

Dear sir,
In the recommendations I only see mention that if the working temperature is above 700 degrees F then 309 cannot be used. Also I can't find any other document that talks about using 309 as a butter layer between ErnicrMo-3 and 7018.
as for other requirements i cant find any mention.
And there are some other suggestions that say to use carbon free Iron ( Kardo lincoln or OK53.xx Esab).
Do you have any document mentioned please share with me. And i would appreciate it.
Thank you.

 

[weldstan]

While it can and has been done, will the manufacturer/contractor have the proper controls to successfully make the welds, especially when done in the field?