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SS & Copper Weld

08/16/2017 11:19 PM

How can I weld S.S material with copper.

This will be use at chiller PHE

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Mostafiz

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#1

Re: SS & copper weld

08/16/2017 11:24 PM

..."An important aspect of welding stainless steel to copper is the physical design of the joint. Problems occur if the joint is designed where the weld energy comes through the copper first. Copper, being a great conductor of heat, tends to require a significant amount of welding energy before it melts. The high amount of energy causes two problems. First, the extra energy causes a larger than necessary heat affected zone and thermal distortions. Second, as the energy comes through the copper into the stainless steel, its high energy basically disintegrates the stainless steel causing holes and blow outs. A much better design would be to have the weld energy come through the stainless first and then into the copper. The advantage of this design is the right amount of heat can be applied to fuse the stainless to the copper. Any extra energy is quickly dissipated into the copper, much like a heat sink. The design gives a much more forgiving weld, and ultimately uses much less energy to fuse the parts.

Electron beam welding is the preferred welding process for welding copper to stainless steel. The main reason for this involves the fact that EBW is a great process for welding copper in general, which is the more challenging of the two metals to weld. The electron beam has a very high energy density, which is not significantly impacted by the thermal conductivity of the copper, nor copper’s high reflectivity. The energy of the electrons quickly penetrates the surface of the copper resulting in a very narrow and deep weld pool. This pool can then be easily controlled to the required penetration depth. "...

https://www.ebindustries.com/CU_to_SST_Welding

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#2

Re: SS & copper weld

08/17/2017 1:15 AM

Furnace and/or vacuum brazing may be a better process for this. Another method might be gasketed construction.

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#3

Re: SS & Copper Weld

08/17/2017 7:17 AM

Avoid welding (melting base metal) joining of copper to stainless. The HAZ will invariably crack.

Most reliable is silver brazing.

There may be TIG brazing/bronzing options depending on your copper and stainless alloys.

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#8
In reply to #3

Re: SS & Copper Weld

08/17/2017 11:22 PM

GA silver solder brazing is the best option, I have done lots of this type of brazing on pressure lines with no failures.

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#4

Re: SS & Copper Weld

08/17/2017 9:10 AM

Both are solderable.

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#5

Re: SS & Copper Weld

08/17/2017 10:43 AM

AG+ Borax

https://www.youtube.com/watch?v=uC-TpstDVH4

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#6
In reply to #5

Re: SS & Copper Weld

08/17/2017 11:14 AM

'Ag' would be more recognizable.

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#7
In reply to #6

Re: SS & Copper Weld

08/17/2017 2:50 PM

Silver is a chemical element with symbol Ag (from the Latin argentum, derived from the Greek ὰργὀς: "shiny" or "white")

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#9
In reply to #7

Re: SS & Copper Weld

08/18/2017 4:23 AM

Mmmhm, that's correct.

That is what you intended when you typed 'AG', instead of 'Ag', right?

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#10

Re: SS & Copper Weld

08/18/2017 8:14 AM

Are you sure you want to even do this? When we have copper (chilled water feed to stainless steel heat exchanger) to stainless steel joints in our WFI process skids, we always use threaded connections and install a dielectric coupling between the two different metals. Now the potential difference is not extreme between these two metals, but still great enough that our customers require the dielectric coupling to be installed, and they are in a position to have seen the outcome of not installing one once the interface is actually in use.

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#11

Re: SS & Copper Weld

08/18/2017 10:40 AM

For a welded joint, you will need what is referred to as a transition joint. For stainless and copper you need to clad weld the copper side with several layers of monel, 70% nickel, 30% copper. You can then join the clad surface to the stainless. I have seen cases where the transition starts on the copper side with a clad of 70% copper, 30% nickel, a second clad of monel and then a fill of monel to join the monel clad to the stainless. Throughout the process you check each layer with liquid penetrant and fix any pinholes, cracks or shrink holes before going to the next layer.

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