Silver solder question

admin

I've got a couple general questions about brazing some copper fittings w/15% silver rod. We've got a heat transfer module coming up that requires the joints hold 175lbs. 99.9% of all our other jobs, lead-free solder and MAPP gas is plenty. I haven't done any silver in 20 years, so there is some major rust. It struck me odd that the pieces were the standard SCH-10 copper fittings and pipe. While all the screw fittings are #300. It would seem to me that to get a proper weld on this, the copper fittings and pipe are not going to be too happy with all the heat from the O/A torch. We will be doing a hydro test on this for leaks afterwards. Any good tips would be greatly appreciated?I'm pretty certain we have a #1 tip somewhere.Heavy w/the flux, or keep it light?Keep the torch 90-180 away from the rod?Bad to quench these fittings?I imagine the 'egging' to be much worse.
Reply:clean the fittings, light coat of flux, feed rod 180, dont quench,  depending on pipe size you can use a turbo torch and mapp
Reply:Why not just use Silphos solder. No flux required on copper, the phosphate in the rods does the job. Work great too.
Reply:Originally Posted by walkerWhy not just use Silphos solder. No flux required on copper, the phosphate in the rods does the job. Work great too.
Reply:I appreciate all the tips and advice. The job went relatively smooth.  A question about the Silphos solder. Does that mean you don't have to flux up the joints before you put them together? Just clean 'em up and hit with the heat? I'll mention those sticks the next time it comes around. They had already bought some flux and a couple packets of rod before my original post. We were unable to get the flame 180° from the rod on the large pipe. The copper just cooled off too fast to get that far away. We did get a good bit past 90° though and plenty of rod got all the way down to the bottom of the fittings. Was a little tough getting a pretty looking cover pass on it. But oh well, the paint will smooth that out. That thin walled copper damn sure keeps you on your toes too! Once it get's all cherry, it only takes a millisecond of hesitation with the torch to melt a fitting. The heavy brass fittings were, of course, much easier than the copper. No solder leaks and just a couple of screw pipe ones made us happy for sure. The silver doesn't seem as it would be as easy as the soft solder to fix or make changes to. Here are a couple shots of the finished product.