What to use to braze copper to stainless steel?

[twophase]

Hey guys. Anyone have suggestions on what brazing alloys will work for brazing copper tubing to 304 stainless fittings? This is a plate heat exchanger as an r134 evaporator. Thanks in advance.

[2sac]

silver solder

[t527ed]

silver solder

+1 the good stuff and the white paste flux.

[twophase]

silver solder

So when you say silver solder, I assume it's different from the lead free plumbing solder? I know that's got a decent ammount of silver in it.

I have a little bit of blue flux coated rod that looks like it's a pretty high silver content. Anyone know what that might be? I only have six 3/8 in. joints to make and those packs of high silver alloys are brutally expensive. If the silver plumbing solder will work, I'll probably just try that since it is just a personal project, long term reliability is not a major concern, and it's on the low pressure side. If not, I'll just have to cough up the $$$.

[2sac]

So when you say silver solder, I assume it's different from the lead free plumbing solder? I know that's got a decent ammount of silver in it.

I have a little bit of blue flux coated rod that looks like it's a pretty high silver content. Anyone know what that might be? I only have six 3/8 in. joints to make and those packs of high silver alloys are brutally expensive. If the silver plumbing solder will work, I'll probably just try that since it is just a personal project, long term reliability is not a major concern, and it's on the low pressure side. If not, I'll just have to cough up the $$$.

Safety Silv 45% . Plumbing solder will not work. Sears sells the coated rods the others are talking about. Any welding or gas supply store should have those also.

[jimp]

Hey guys. Anyone have suggestions on what brazing alloys will work for brazing copper tubing to 304 stainless fittings? This is a plate heat exchanger as an r134 evaporator. Thanks in advance.

I just did a couple and used 45% with the Harris white paste.

[ryan1088]

I just did a couple and used 45% with the Harris white paste.

I was thinking 45% coated rod.

[jimp]

I was thinking 45% coated rod.

I like to control the flux, and brush it on before I braze.

[jackintheboxtec]

The orange coated rod

[supertek65]

X2

I use 50%flux coated rod
And paste.

The real trick is EVEN heat.

I use a smith torch with the round tip.

The orange coated rod

[grkmano]

stay bright? with flux

[monkeyman#1]

56 percent silver and flux, does a great job, nice flow

[supertek65]

NO 95/5 solder will NOT work!

The blue rod will work.

Orange better. 56% silver. 23% copper. Zinc and tin.

You buy it by the rod

You only need one!

[2sac]

Also, stainless heats up at a quicker rate than copper and is easy to burn thru.

[supertek65]

Oh
There is no silver in 95/5
95% tin
5% antimony

[Capz]

If you do not know what to use, you likely don't know stainless soldering takes a different approach. Here is some help.

45% silver solder or better with white or brown flux to start but always point your flame at the copper allowing the ss to only get near the flame. once the solder melts onto the copper, move some heat onto the ss. And don't burn the stainless. It'll get black. Once you do, you will need to wash off your joint with cold water and do it again. Be sure your ss is clean to start with. Unlike sil-fas, you need to clean the copper & stainless with emory. Wash off harden flux with cold water and rag while the joint is still hot. Good luck.

[jmac00]

JB weld

LOL

[twophase]

If you do not know what to use, you likely don't know stainless soldering takes a different approach. Here is some help.

45% silver solder or better with white or brown flux to start but always point your flame at the copper allowing the ss to only get near the flame. once the solder melts onto the copper, move some heat onto the ss. And don't burn the stainless. It'll get black. Once you do, you will need to wash off your joint with cold water and do it again. Be sure your ss is clean to start with. Unlike sil-fas, you need to clean the copper & stainless with emory. Wash off harden flux with cold water and rag while the joint is still hot. Good luck.

Ok thanks for the tips.

Also, didn't know brazing rods were sold individually. I'm small time (just personal and school design projects), so I've been able to just pick up the half used rods left behind by the likes of you guys at the ice rinks I work at. I'll see what airgas has when I go to get nitro tomorrow.

[Capz]

Ok thanks for the tips.

half used rods left behind by the likes of you guys at the ice rinks I work at. I'll see what airgas has when I go to get nitro tomorrow.

Those half rods are sil fas rods likely 6% silver. May not work with copper to ss.

[twophase]

Those half rods are sil fas rods likely 6% silver. May not work with copper to ss.

Yeah, mostly Dynaflow, but a few 15% sil-phos. I have found 4" of the blue rod. I just clamp them into some vise grips pliers and use 'em the rest of the way up. 1/4" joints don't need much.

But I picked up some of the safety-silv 56 orange rods and white flux, so it should be good. $40 for a pack of 3...could be worse. I was a little surprised 20 cu ft of nitrogen cost $20. Maybe it's gone up.

Thanks for the help, guys.