soft solder issue on PC

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soft solder issue on PC

Postby B-Man » Mon Apr 12, 2021 7:14 pm

still has been working a treat for the last year. last run I noticed it had a few drips before the fore's come out. finished the run off and pulled the PC out.
pressure tested it and it had a tiny pinhole leak at the top where the tubes come through the plate. it pressure tested fine when built and held pressure for 24 hours with no bubbles in a tub of water.
For the life of me i cant get it to stop. if i fix it somewhere it leaks somewhere else. cleaned the thing reflowed it. melted it all off ground up the surface and re soldered it still leaks somewhere. ran the smallest amount of solder it leaks put a heap into it it still leaks... soldered it as hot as I could still leaked soldered it just enough for the solder to flow just dabbing the heat into it and flowing the solder and it still leaks.
i have tried over 40 times (no joke) and it still leaks any tips...?

I think it would have been quicker to make a new PC :cry:
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Re: soft solder issue on PC

Postby RC Al » Mon Apr 12, 2021 7:48 pm

Pick a hard core acid you are comfortable using and use it inside the water jacket, neutralise and try a few more times, I dare say corrosion inside the pc is your issue with the leak and the soldering
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Re: soft solder issue on PC

Postby B-Man » Mon Apr 12, 2021 8:05 pm

cheers will give that a shot.

Find it strange I can fully cover it with solder and it leaks through it on the join that is over filled
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Re: soft solder issue on PC

Postby RC Al » Mon Apr 12, 2021 9:47 pm

If your using bakers liquid flux, that would prob do the trick
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Re: soft solder issue on PC

Postby B-Man » Mon Apr 12, 2021 10:14 pm

Yeah already used that a few times in the process of the welds.
Have it soaking in a citric acid bath until tomorrow night then see how I go.
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Re: soft solder issue on PC

Postby scythe » Thu Apr 15, 2021 8:17 am

I had a similar thing happen to my RC.
I made it then pressure tested OK, gave it a soak in citric to help clean up the flux and sat it on the shelf for a long while.
Attached an elbow to my water connection, melted nothing else.
Pressure tested again and it was a sprinkler.
I put it down to not washing the citric off properly, and it ate through the solder where it was thinnest.
It also ate into the copper.

I had to cut 5mm off each end of my RC and buffed it all back to bright clean copper before I got it to seal again.
Gave it a good soak and flush in water this time.
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Re: soft solder issue on PC

Postby B-Man » Thu Apr 15, 2021 9:17 am

Update.
Got it to seal with about 2L of bakers soldering fluid.
Realised with the 2 rolls of solder I had pumped into it previously it had blocked some of the shorgun tubes so drilled that out and ended up puncturing 2 tubes.
Had to de solder the whole thing.
Will get new tubes and try again. Will replace the whole lot as I dont know how badly damaged the others are.
I had 5 tubes in the shotty. And pros/cons with 4 vs 5? Can/ might have to make new plates anyway
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Re: soft solder issue on PC

Postby B-Man » Fri Apr 23, 2021 8:03 am

second update.
got some new tube.
cleaned and dosed in bakers solder fluid.
soldered in place. soldered once and no leaks ^:)^

still thinking of making a longer shotty to get it further away from the still if i want to run gas for quicker heat up.
if you go longer can you run less tubes through it? or would it stat getting too heavy? I was thinking 4 tubes through the longer one but thinking about weight and might aswell go 5 again ?
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Re: soft solder issue on PC

Postby scythe » Fri Apr 23, 2021 3:09 pm

I don't have time to do the maths now but I would guess that a tube of any length weighs less that the water it displaces.
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Re: soft solder issue on PC

Postby B-Man » Fri Apr 23, 2021 8:35 pm

yeah that was my thought. even if i could get away with doing 4 for a longer pc it would weigh more so might as well go 5 again.
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