How to joining CRA pipe to CRA pipe? ( Claded incoloy 825, thick 5mm and base material thick 12.7mm) 3

[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?

 

[taliban999]

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?

Dear sir, thank you for giving me advices
if there is any information or documentation on this issue, all will be considered. if not, Ernicrmo-3 will be used, but it is really too expensive.
Do you have any documentation on this issue that I can refer to?

 

[kingnero]

Do you have any document mentioned please share with me.

Regarding the Ni-based filler, check the website of the Nickel Design Institute. Lots of very informative, and practical useful info there.

And there are some other suggestions that say to use carbon free Iron ( Kardo lincoln or OK53.xx Esab).

All fillers will have low carbon. The problem is the carbon (and other alloying elements) in the base metal, that might cause problems.

Ernicrmo-3 will be used, but it is really too expensive.

The alternatives won't be much cheaper...

 

[taliban999]

Regarding the Ni-based filler, check the website of the Nickel Design Institute. Lots of very informative, and practical useful info there.


All fillers will have low carbon. The problem is the carbon (and other alloying elements) in the base metal, that might cause problems.


The alternatives won't be much cheaper...

Dear Sir,
Thank you
About PWHT and preheat, ASME B31.3 advise that PWHT is necessary but UCS 56 say that Once you preheat the weld, you won't need to PWHT.
and i plan to just heat it to dry the surface and keep the heat between the weld layers around 95 degree C, is that correct ?

 

[kingnero]

i plan to just heat it to dry the surface

Will the welding be performed under your supervision/responsibility, or will a contractor be doing it, and you just want to verify his procedure?

and keep the heat between the weld layers around 95 degree C?

Is that for the Ni, the 309 or the carbon steel? You have three distinct phases in the welding. It's important to be specific in all three, and if any PWHT, you do it at the right time. Not necessarily at the end. 309 doesn't particularly like PWHT.

I suggest you (or your contractor) get a competent welding engineer to assist you, as there are many ways this could go south really fast.

 

[taliban999]

Is that for the Ni, the 309 or the carbon steel? You have three distinct phases in the welding. It's important to be specific in all three, and if any PWHT, you do it at the right time. Not necessarily at the end. 309 doesn't particularly like PWHT.

I mean after the above advice I would opt to use only Er/Enicrmo-3 for the entire weld. Preheat or PWHT for the entire weld by Er/Enicrmo-3.

I suggest you (or your contractor) get a competent welding engineer to assist you, as there are many ways this could go south really fast.

I want to do some research before I hire a welder. Because I really don't know any qualified welders around here.

 

[kingnero]

I don't see any advice above leading you to use E(R) NiCrMo-3 for the entire weld. I also wouldn't be in favor of this, as I mentioned above.

And, again, you don't need a qualified welder to advise you how to proceed, but rather someone with a metallurgical background.
Someone that might ask questions like, what medium passes through this pipe, acid, brine, Cl-, at what temperature, how are you going to shield the inner diameter, ...

 

[taliban999]

When I check the hardness of these welds. There is a recommendation for this, as long as the hardness of the HAZ is less than 248HV10, it is fine?. Is this correct if I use E(R) NiCrMo-3

Tôi không thấy lời khuyên nào ở trên hướng dẫn bạn sử dụng E(R) NiCrMo-3 cho toàn bộ mối hàn. Tôi cũng không ủng hộ điều này, như tôi đã đề cập ở trên.

Và một lần nữa, bạn không cần một thợ hàn có trình độ để tư vấn cho bạn cách tiến hành, mà cần một người có kiến thức về luyện kim.
Có người có thể hỏi những câu hỏi như, môi trường nào đi qua đường ống này, axit, nước muối, Cl-, ở nhiệt độ nào, bạn sẽ che chắn đường kính bên trong như thế nào, ...