Long-term longevity of suspect sweat joints

[Brian Kehlmeier]

I find sweating copper very easy to do, yet these large mass brass fittings always give me trouble. I used Oatey's No 9 tinned flux to sweat a shower valve and 3 of the 4 joints give me worry. I am not sure if the flux burns off, but I could see it bubble then stop. I don't recall much smoke before applying the solder but it balled up a bit before it would melt. I think using propane fuel is part of my issues. I have to heat it up for so long to get the solder to flow; something like preheat the copper for 20-30 seconds then the brass body about an inch lower than the joint at all four angles as well, then start heating the joint to get it to flow.

No leaks are present when testing, but should I worry about leaks in the future if I am not confident that solder flowed into the joint? I also wonder if the tinned flux gives me a greater margin of error.

 

[Tuttles Revenge]

The only way to see if a copper joint will leak.. is if it leaks. you cant see inside. Only your confidence in your ability is your double check.

You could take the copper out of one joint to see if there are any blank spots, but that's no guarantee as you may get perfect spread just in the act of moving the joint.

 

[Sponsor]

 

[Kreemoweet]

A sweated joint does not have to have 100% solder coverage to be reliably leak-free.

 

[Sylvan]

When we used copper TP water piping to properly braze the joint was to heat the pipe then the brass fittings all around to allow capillary action to draw the alloy into the fitting.

The same principle holds true for soldering.

About the remark "A sweated joint does not have to have 100% solder coverage to be reliably leak-free"

When I did Oxygen and Nitrous oxide piping (type K copper dehydrated ) the joints were spot checked with an X ray and if the joint did showed any voids it failed and the entire system was then checked.

If the copper / brass are cleaned properly there should be no voids