The Steamboating Forum

Hi,

I am set to start plumbing. I ordered McMaster Carr 7675A4 solder. The composition is Ag/Cu/Zn/Cd // 35/26/21/18, (Silver/Copper/Zinc/Cadmium).

The melting point is 1125 to 1295F. Ron Rogers suggested I use an oxy/acetylene torch but I dont trust myself with it....... it would be a shame to burn the garage down before I get the boat in the water.

Will I be OK with a propane torch, or do I need to go to MAPP gas ?

thanks in advance for the help.

jon

I would just try it on a test piece. If it flows well, you are fine. Typically these solders are rather runny.
Make sure there is a small gap for the solder to flow in between flat surfaces. I use a spring loaded punch to make some little bumps so there is a thou or two of gap. Use good flux.

Mike

Oxy/cet is the quickest, and that means the heat doesn't have time to travel too far beyond the distance required. It is what we used to recomend to refrigeration engineers.

Propane will also do it, but as the flame is much bigger you may want to use some shielding of surrounding stuff. Ali sheet or even steel will suffice, but watch the edges as the flame goes much further than you expect.

You didn't say if your rods were fluxed or fluxless, that makes a difference to your prep.

Leave the joints to cool as naturally as possible.

Surprised you can get cadmium bearing silver solder still.

I use MAPP gas regularly with complete success, a couple of points though; if soldering brass components, swap to Propane only, MAPP gas can be very corrosive towards brass and seems to increase brass' tendencies to melt closer to soldering temp. Also, in the UK it's about half more expensive than Propane, so use MAPP only when you need to.

Many use Oxy-Propane- best of both worlds, and far cheaper than Oxy-Acetylene, as well as far safer to store.

Regards,

Greg

Cadmium makes for an easier soldering job, it results in a larger soldius range, compared to other silver solders which generally have a quick transition from solid to liquid. Cadmium is however a serious health hazard, and has been outlawed in many places. Be sure to use good ventilation so you don't inhale the fumes.

I have used this solder for many applications, and the common propane torches are really only good for small jobs, up to about 1/2 inch diameter tubes. MAPP is needed for larger soldering jobs, I used MAPP to put tohether my engine exhaust system, Type L Copper at a little over one inch diameter. The Oxygen torch setup of course can provide plenty more heat, but is generally more than is needed for making up most connections.

fredrosse wrote:Cadmium makes for an easier soldering job, it results in a larger soldius range, compared to other silver solders which generally have a quick transition from solid to liquid. Cadmium is however a serious health hazard, and has been outlawed in many places. Be sure to use good ventilation so you don't inhale the fumes.

For those in US- it is now illegal to supply Cadmium bearing solders in the EU, as well as being illegal to use in the workplace.

Greg

HEEEEELLLLLLLLLLPPPPPPPPPP !!!!

Hi,

I tired to sweat a couple of joints today and had no success at all. This high silver solder is not taking at all. Here is what I did:

1. Cleaned both female and male fittings
2. Applied flux to all surfaces
3. Applied heat to the joint, tested the solder to see whn it was hot enough to melt
4. When it started to melt applied it to the joint "normally", the same way I woulod sweat a regular copper water line.

The solder just beaded up and did not draw into the joint at all.

Should I be using a special flux for the higher heat ? I seem to be losing a lot of flux in the heating process.

jon

Flux for ordinary low temperature solders is useless for silver soldering. The active temperature range of the flux must match the melting point of the solder used.

Thanks Fred !

Can you tell me what combination of solder and flux you use ?

jon

Your solder's temp range is wider than any solders I can see that we have, so maybe your fluxes are different too (they are usually Borax compounds) are you sure it's correct?. Most s/solder fluxs here are supplied as a powder and should always be mixed to a paste with clean water. If while soldering a little more flux is needed, then the rod may be dipped either in the power (which will stick to the hot rod), or in the paste.

As with all soldering 'cleanliness is next to Godliness'. Speed also helps, as the flux will burn away if left too long in the flame.