re-solder leaking joint?

No leaks (known yet) just getting myself prepared once the final rad is in
place.
If once I open the valve and let the water into the system, I find a leak
(or leaks), can I throw some flux and solder onto the offending joint with
the water inside?
if not, I guess its a full drain down again is it?
TIA
Reply to
Vass
AND careful drying of the offending parts .... one can't get the pipery to solder-melting temperature while there's water in / near the pipe/ { Although I once saw an mechanic accomplish this using something he called 'Killed Spirits', which came in an earthenware jar, as a flux and an ENORMOUS electrical soldering iron roughly the size and shape of a Roman gladius }. An old trick was to push bread into the pipes to give a temporary blockage to the pipes - which , in theory, would dissolve later.;- not that I'd try this on a sealed circulating system.
Reply to
Brian Sharrock
OK, so if I have an "iffy" joint, whats the best way to try to ensure its good enough?
I've used active flux on it (after heating with torch) then fed solder into the joint looks ok from the outside, but who knows Is there a better way? (all joints were Yorkshires) thanks
Reply to
Vass
In article , "Vass" writes:
It's a drain down (to below the height of the leak). Even small amounts of water still in the pipework will prevent it being soldered. If a joint leaks, you may be very lucky with reflowing the solder, but it's more likely to be a dry joint where copper oxide is preventing solder flowing, so more often you will have to disassemble, clean up all the parts and start again. This is why it's really worth doing the cleaning job right first time; steel wool to bring the copper up bright and shiney on both the pipe and the inside of the fitting.
I pressure tested my system with air before first filling with water. There are several advantages to this. If you find a leak, everything is still dry so it's easy to fix. Air leaks are easy to detect using gas leak detector spray. Air leaks out much faster than water, so if it's air-tight, it's most definately water tight. No secondary damage from water leaks (could be quite a lot of water if a connection blew right apart). I suspect I got the system more water- tight this way than sealed systems normally are -- it's only needed topping up once in 5.5 years, and that turned out to be due to a rubber o-ring on a radiator blanking plug starting to fail. All the leaks I found during the pressure testing were in the compression fittings on the radiator valves, and the radiator tails. The pipework was all soldered using end-feed fittings, and none of these leaked.
NOW, A WORD OF WARNING. Pressurising a system with air to detect for leaks can be dangerous. You end up with a lot of energy stored in the system, and if something fails catastrophically, there's a lot of energy waiting to blow the parts to pieces. I believe the relevant BS says the building should be vacated of everyone except the tester when pressurising a system to minimise risk of injury if some component explodes. I tested the system on small sections as they were assembled -- no more than two radiators. The final testing was then done with all the radiators shut off at both ends, so they weren't acting as a pressure resovior (quite apart from the fact it would have killed me trying to pump up all the radiators at once with a bicycle pump -- even just two at once was bad enough).
Reply to
Andrew Gabriel
make sure the solder has gone all the way round the joint and it was cleaned and fluxed well.
Reply to
zaax
In article ,
You can't solder with *any* water present. Even if the torch could get it hot enough there's a good chance of steam blowing holes in the solder. It needs to be absolutely dry before attempting it.
Reply to
Dave Plowman (News)
Agree with all this of course, and certainly the counsel of perfection, but I'm surprised no-one has mentioned
1) the "radweld" type sealers 2) the plumbers' epoxy.
Havn't used the former, but used the latter successfully as a temporary (3 year) repair on a very inaccessible HW cylinder (probably a split on an overstrained flange).
Reply to
Newshound
Clean the pipe well - the blue pipe cleaner that wickes do for about a fiver is very good - has internal wire brushes that will get it shiny in a few twists. Use a slightly aggressive flux - Fry metals powerflow is fairly mild but does a nice job. Make sure the joint is hot enough all round. Also ensure the pipe is fully home in the fitting.
Yorkshire does not need solder fed in really - just heat until you see a bright ring of it all round the joint.
Personally I find I get a 100% success rate with end feed fittings, but very slightly less with Yorkshire fittings.
Reply to
John Rumm
Same here. Best money I ever spent. The pressure tester is a pressur guage, with a not-presta (whatever the other one is called) valve, and a push-fit fitting. Works a treat.
Same here. My end feeds used to leak until I bought a proper blow torch. Still have a bit of trouble with draincocks though...
Well the energy stored is proportional to the volume. Like you, I wouldn't fancy pumping enough energy into a system to make it dangerous.
Ben
Reply to
Ben Blaukopf
Schraeder valve, I think
Taking out the centre component with the seal is a good idea. a) there is less to heat and b) it avoids melting the seal.
Buying a good quality one and cleaning it well is good.
Apply flux and then heat starting at the outer end of the drain cock brass component and moving towards the copper fitting. This reduces conduction of heat away and boiling off of all the flux.
Reply to
Andy Hall
In article ,
First it's a complete waste of money buying yorkshires if you're going to add solder. Use plain end feed instead - not only are they much cheaper but they look better too.
If everything was clean, you used a decent flux, the solder flowed and you didn't move anything before it set the joint will be perfect. But to convince yourself make up one using scrap pipe and take it apart afterwards - you'll find the mating parts perfectly tinned.
The only fault I've ever had was a pinhole on an elbow. Which could happen as easily on any type of joint.
Reply to
Dave Plowman (News)
Killed Spirits was Zinc Chloride, made by dissolving zinc in Hydrochloric acid. We used it in metalwork at school to make the compulsory tinplate mug. I didn't have much success with it on copper.
It was also available under the trade name of Bakers Fluid, but I see Baker's Fluid comes in about 5 "flavours" now. I prefer the resin type pastes. They work every time if the copper is completely clean and shiny and there is no trace of water about, not the slightest trace, mark you.
DG
Reply to
Derek Geldard
We didn't do tinplate mugs, but we did a tinplate boiler with a turbine on top, using a medicine-bottle cork as a safety-valve.
I'm sure some boys tried to run them without water in the boiler and the whole lot of joints melted. Similarly, some ran them on too high a gas ring with the cork rammed in too hard and the whole lot exploded, bits flying around the workshop from near the brazing hearth.
I'm proud to say that my tinplate pastry cutter with its arched handle was shown by 'Archie' Campbell to the whole class of how soldering should be done - proper filleting of the solder etc. I wish my Mum still had that 'project'...
We used to make the killed spirits flux too.
That was a great workshop (W5). There were 4 metal workshops but this one had two Harrison screwcutting lathes, two ancient overhead shaft-driven lathes, power hacksaw, shaper, planer, two pillar drills, brazing hearth, two 'moulding' stations, a couple of benches for repousee/rivetting etc, a surface plate/marking out bench and four forges/anvils, as well as the usual four boys to a bench. We used to do scraping of flats using engineer's blue...
This was a grammar-technical school. Sadly now, virtually all the machinery has gone apparently, and I think they'd have difficulty cutting up pieces of cardboard nowadays.
Still, all our engineering can be done by the Far-Easterners nowadays... :-((((
Reply to
Frank Erskine
In article ,
I made a tinplate dustpan at school in the '50s - wired edges, riveted handle, which of course my dutiful mum used until she moved into sheltered accommodation. And it now gives sterling service in my workshop...
Reply to
Dave Plowman (News)
Yoiu can, but it won't do anything useful ;-)
Only the pipe to be soldered..how you achieve THAT is of course a moot point.
If at all possible assemble bits of pipe and elbows away from main pipe runs where they can be tested as sub assemblies by sucking on them.
Then at least there is generally only one joint that you haven't tested before filling..and a compression joint.
Reply to
The Natural Philosopher

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