Big soldering

[Richard T]

I have an old (1930s) copper boiler that has popped its soldered joint around the pipe that comes out of the bottom and goes to the tap.
The bottom is domed and around three inches from where the wall starts there is a flange into which the pipe is (was) soldered. It's quite grotty as this is in the area that the gas flame has done a lot of sooting up over the years and it is impossible to get the pipe out of the flange to clean it properly. I've cleaned it as best I can in situ. and fluxed it - I suppose the best I can hope for is that the solder already in the joint will spread and mingle with new solder to close the gap.

Also I am concerned that my blow lamp won't be up to it - a bog standard butane canister job - quite good for standard stuff but maybe not up to heating a joint this big ... any idea of the sort of torch I should be thinking of?

This is all academic for now however as I still have to get the gas ring off (seized nuts) before I can get to it properly.

 

[doorframe]

A second blow lamp.... one from each side. I've had to resort to this in the past.... with the solder fed in with my teeth!!!!
(Solder don't taste too bad, but flux..... yukkkkk!!!!)
Lost my eyebrows more than once, though!

Roy

 

[jasonB]

A 1" torch on the end of a 4.5kg propane bottle will get it hot enough for soft soldering.

You may have problems with the old lead based solder not mixing with newer lead free. I'd try and get the pipe out clean both surfaces back to bare copper, tin with new solder and then sweat the joint back together feeding in some more solder.

J

 

[Digit]

with the solder fed in with my teeth!!!!

WIFE WANTED! MUST HAVE OWN BLOWLAMP!

Roy.

 

[Richard T]

Thanks folks.
I haven't had a go yet as the nuts and bolts holding the gas ring on still refuse to part company after may applications of paraffin and 3in1 ... so it's the grinder for them tomorrow.

Roy, I thought of the two blow lamp approach too .. I had a lovely Ronson High Heat one til the gas ran out and I found it had not been made for years so now I am stuck with my one butane, or with SWMOM's small jewellery one on the other side - not ideal.
So I had a look around the net for what I really wanted - Jason; a straight-off-the-propane-bottle job ... £129 :shock: so I don't think that's going to be an option for this one off. Also I have lots of ancient solder that is certainly lead based.
No possibility of getting the pipe out I'm afraid - the nuts that hold it either side of the outer sleeve are bigger and rustier than those holding the gas ring.

And (Other) Roy ... Got one ... Though could try harder with the blow lamp ...

 

[No skills]

Have you looked on evilbay? propane blow torch brought up a few different types.

 

[Eric The Viking]

Propane is hot; MAPP gas is hotter and you can easily braze with it (see below).

Toolstation keep both in disposable bottles, for Rothenburger-type handsets. Don't bother with the cheaper copy handsets - I bought one that is now being used as a gas ring lighter (no good for anything else!). The Rothenburger type are outstanding, I use mine for tempering/hardening chisels!

The actual burner makes a difference, too: Primus-Sievert designed a 'cyclone' burner in the 1980s for propane. I think the patent's run out now, as I've seen copies about. Basically, it sends the flame out in a spiral (a number of small jets inside the nozzle, angled in a circle). The idea is that the flame wraps round a cylindrical object such as a pipe, so that you get better, more even heating. It really works well, as not only does it heat the pipe very well, but there is little spill. With care, I've made joints within three inches of joists and wallpaper without scorching them. I've got the effect to work with pipes up to 28mm diameter (it helps with 35mm but you can see it's not wrapping all the way round). They're worth a go if you can find one, and one running MAPP gas would be the dog's...

You can still get lead solder for plumbing, and my advice is to use it! The modern lead-free stuff has a higher melting point, does NOT tin very well, and is more brittle when cooled - so much so that automotive applications have an exemption from the EU directive (IIRC). In my limited experience of trying to work with it, the two different amalgams don't mix at all well. Beware using plumbers flux with the hotter gases though - in my experience it's actually easy to overheat the copper, so that it doesn't tin well - you have to time it just right.

In theory, your flange ought to be brazed (silver soldered) though, because, if I understand your description correctly, it's receiving direct heat from a burner. Whilst the inside won't go above 100 degrees C (assuming it's not pressurised) the flame will be far above solder's melting point. Brazing is a whole different can'o'worms though. You need a different flux and (ideally) at least MAPP gas, and it's beyond my own experience with that sort of shape of workpiece.

Regards,

E.

PS: just had a thought: It's the sort of thing model engineers do quite a bit (steam engines). Their boilers have to be pressure tested for safety, so the brazing has to be spot-on. Is there a local club who might help for beer tokens, possibly?

 

[jasonB]

Don't know where you got your prices from but this one is £100 cheaper, you may also be able to hire something for a day

http://www.machinemart.co.uk/shop/produ ... th-nozzles

Its not the gas that gives you the heat when the jobs get large its the BTU rating of the burner nozzel, small canisters just can't supply enough gas for teh big burners so thats why propane bottles are better. I use them for my model engineering when silver soldering and that needs temps of 630 deg C upwards.

Regarding the joint comming into contact with the gas ring flame, provided the boiler does not get run dry the heat sink effect of the water and large area of copper will stop the soft solder from reaching melting point. Its just like trying to solder a pipe thats still got some water in it you will have a hell of a job getting solder to flow.

J

 

[Richard T]

Thanks Eric,
It doesn't have to cope with any pressure, it's just an old washing boiler. The solder that the pipe is tinned with is very soft and I am guessing just lead solder - when in use would be full of water.
Both SWMOM and I only use borax as flux; me for forge welding (not that I do much) and she for jewellery soldering - not to get mixed up with 'silver soldering' - actually soldering silver. So these are both hotter activities and I may need a flux more suited to copper and lead ...?
Trying to find a local steam model group might be a very good idea.

Thanks Jason - I had been looking at this one
http://www.tradecounterdirect.com/solde ... _type.html
which isn't the most expensive. Though I would love one, I can't see the justification at the mo'

There are a few hire shops around. Well worth a try I should think.