When is soldering advantageous over brazing?

[liko25]

I need to install a brass flange on a 3" OD Type K Copper Pipe. The operating pressure will be <150 psig. My initial thought was to braze the flange to the pipe for a stronger joint. However, I've been debating if that is overkill and should simply solder the joint together. Are there any significant reliability or fabrication advantageous to consider with a soldered joint instead?

On a related question, I need to transition from 3" copper pipe to 2-1/2" stainless. I was simply going to use a 3" brass flange on the copper pipe which bolts to the stainless flange. Is there any advantage to brazing a stainless flange on the copper pipe instead? Or does that lend itself to reliability problems down the line?

 

[1503-44]

https://ewi.org/should-you-solder-it-or-braze-it/

 

[EdStainless]

Soldering is easier, lower temp and not as aggressive flux.
However it lower strength and often lower corrosion resistance than brazing alloys.
You can braze the brass flange to the Cu pipe as option.
Brazing SS to Cu is tricky.
I personally dislike brazing SS because it is easy to cause issues (sensitization for one).
We had "K" copper pipe for Ar and N2 lines that were all brazed. Our He and H2 lines were all welded SS.

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P.E. Metallurgy, consulting work welcomed

 

[liko25]

-thirtytwo,

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good link! Thanks for sharing

EdStainless -

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yes, I'm leaning towards brazing the the brass flange to the Cu pipe. This is for a water cooling supply line. I guess in the end what I'm looking to do is have the most reliable joint, so I'm weighing the ease of soldering at lower temperatures to the higher temperatures required for brazing. Is there a larger chance of overheating the material and degrading the flange's properties? Or if I'm confident with the skill of the person brazing, there shouldn't be much to worry about?

 

[Compositepro]

Brazing will anneal copper pipe.