Copper to steel technique

By cool girl Date 09-24-2008 22:12

The company I work for sells refrigeration equipment for special applications. During the installation process a steel valve must be brazed or soldered to a copper pipe. Many installers are having a tough time completing the connection without "pinhole" leaks; residential refrigeration is usually all copper to copper I am told. We have contacted the valve manufacturer, local wholesalers, flux dealers, condensor manufacturers all with the same answer...
" It is a standard procedure and we have no instructions"
We have suggested a 45%- 50% silver rod and Stay-sil flux. Is this correct? We never seem to have a problem with it here in the shop prepping similar components. Could someone point me in a direction to find a video or instructions to offer the installers?

By yorkiepap (***)

Date 09-25-2008 00:53

Hey cool girl,
I would suggest you give solver-solder a try. You can use 60/40, 50/50, or 40/60 and either O/A or oxy-propane. I use Lucas-Milhaupt Handi-Flux for all my sil-sol & braze applications and never had a failure. I find the best results are obtained by wire brushing the joint area with a SS brush & some acetone to get it clean. Then I generally "tin" each surface of the joint with the sil-sol & brush off the excess. Since sil-sol bonds by capillary action, each tinned surface will bond much easier & produce a sound, leak-proof joint. As you heat and the sil-sol melts, connect the 2 joints & add additional sil-sol just as you would soft-solder a copper joint. The capillary action will draw the sil-sol into the joint and just add enough to lay a small bead on the outer surface. You would have best results by running a few test joints to get the "feel" of the sil-sol and which part would need more heat on application. Hope this helps a bit & I'm sure you will get additional input from the knowledgeable fellows here on the forum. Let us know how you fare with your results. Good luck.... Denny

By ravi theCobra (**)

Date 09-25-2008 20:38

I would recomend that you try using Easy Flow 3 which contains ~3 % Nickel in a 50 % silver Solder

This is how we braze copper to stainless steel lines - and they pass helium leak testing -

What kind of torch are you using - you might be getting the joint too hot . . . . .

If you have any further questions get back to me -

By Tomwalz (*)

Date 09-29-2008 15:45

Our web site is being rebuilt. We never know what is up at any given time.

Either follow the directions below or call me at 800 346-8274. Tom Walz

We have braze information on line http://www.carbideprocessors.com/level2brazealloy/level3brazetechinfo.htm

If they are leaks it is cleanliness. Use oven cleaner to make sure they are grease free.

If they are pinholes but not through then my guess is that those are bubbles caused by Zinc fuming because of overheating or the wrong alloy.

Lots and lots of differences in braze alloys when you get right down to using them.

Also fluxes are very different. Most fluxes have a fair (10 -20%) amount of inert materials in them.

We sell a brazing kit for $24.99 with a few feet of braze alloy, flux and instructions. The instructions are the real bargain.

Tom

By cool girl Date 10-01-2008 17:51

Thanks to all you guys on some much appreciated info :)

By ravi theCobra (**)

Date 10-02-2008 17:36

Have you got the problem fixxed yet ?

By cool girl Date 10-03-2008 15:52

Yes and no. I understand more clearly what the problems are that our customers are having. But we still don't have a "simple" description or photos or video to show them what they are doing wrong. I never imagined finding a way to help them would be such a pain in the ass! :)
I might have to do it myself.

By DaveBoyer (*****)

Date 10-05-2008 04:46

Be sure that the customers know that they MUST use flux. Copper to copper joints are done without flux, and if that is what they are used to they may not even have flux on hand.