How to weld corroded copper in the ground

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Mr_David

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Repairs to badly corroded copper found under concrete slabs can be very challenging.
A large percentage of underground copper pipe failures are on hot water lines.
This line here was badly deteriorated on the outside of the pipe.

Others had previously made a repair, buried it and replaced the concrete.

I clean the pipe with a wire brush in a drill. but it doesn't always clean it off well enough to accept solder.
Yeah yeah! I know ! Copper joint under slab should be brazed. That pipe it to far gone to be brazed. Objective is to restore water.

I then heat the pipe until it glows, then wire brush it again.
Next step "Tin" the joint. pre-solder and wipe the pipe.
Check it with a mirror. look for any areas that did not take the solder.
If you have voids, the solder won't bond when you make the joint.
Clean the voids and re-TIN the joint. A new fitting on this badly deteriorated
pipe will fit loose. Careful when soldering. The joint gap will be more than normal. Use a minimum amount of heat to make the solder flow.

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While I am no fan of Sharkbytes, that is one situation where I would use them. Any repair on that pipe is very temporary at best.

Very nice job, though.

Back when I was a kid working in my Dad's radiator shop, we used a tinning compound on pretty much every solder joint. Really helped to make the solder take.
 
Not sure a sharkbyte would work. Pipe has a badly pitted surface and the O-ring in the SB probably wouldn't make a seal.

That place was completely re-piped last year.
 
Completely repiped with two sharkbytes and a capped off branch? Or did you do this repair before the repipe?

This repair was a couple yrs ago. I was going through a bunch of old pictures
Not Sharkbytes. The G-couplings were installed by ?? on a previous repair.
This was a 2 unit blg that had a water heater that supplied 2 other bldgs as well.

A few months after this repair a contractor with a big crew re-piped the whole property.
Guessing 150 units. Yellow outline slab leak. Green outline Whole complex

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How did you pinpoint the leak?

That particular one, water was coming up through laminated wood floor.
I charge the line with CO2. Pulled up the flooring and there was a patch in concrete from a previous repair. So I just opened the patch.
We have electronics that can locate the pipe. Then we listen with an electronic noise amplifier along the line to pin point the leak. Not always accurate. My hearings not so good so we hire Advance Leak Detection Service. One of the ALDS guys we call 50/50. He's right on only 50% of the time.

If the dirt settled under the slab and creates an air gap between the slab and the dirt over a large area then it's even harder to pin point.

I remember pot holing a unit. maybe 8-10 holes. We were following the water flow. Made a big circle. Maybe 10-15 ft diameter. Ended up about 3 ft away from our 1st hole. :eek: I'm surprised I even remember that job. Was back in my rookie days
 

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