Lead welding

[chunkolini]

Hi Guys,
I have a mate who has a problem. he is a builder and has a repair to do on an old roof. There is a small split in a length of lead flashing. How do he weld it?

I went round last night and he was sat in his front room with a blow torch and pile of bits of half melted lead. he can get it to melt ok, but it collapses and there is fusion happening.

My guess is that he needs a flux and a more focussed heat source. Anybody got any ideas/

Chunko'.

 

[runnach]

Hi Guys,
I have a mate who has a problem. he is a builder and has a repair to do on an old roof. There is a small split in a length of lead flashing. How do he weld it?

I went round last night and he was sat in his front room with a blow torch and pile of bits of half melted lead. he can get it to melt ok, but it collapses and there is fusion happening.

My guess is that he needs a flux and a more focussed heat source. Anybody got any ideas/

Chunko'.

Chunko, there are proper small O&A torches for lead welding, or burning as plumbers call it. I welded up some lead planters with success using normal O&A torch with a number two nozzle, at normal gas pressure for a 2 noz.

Preparation: Use a normal triangle shape paint stripper/wallpaper stripper, draw this along the area to be repaired till you view nice shiny lead below oxidized film. For filler, try to get some lead flashing, this will be the same as repair matl. Clean strips using triangle stripper till you view nice shiny lead surface. It is then a case of applying heat to work, dont hang around too long, best if your mate practices on scrap prior to tacking proper repair. Gimme a shout if you require further info.

Cheers......

 

[madkayaker]

he needs an OA with a thin nozzle then some strips of lead as filler not sure about flux.

 

[runnach]

Yes I forgot to mention, no flux required. Also don't be using soldering type lead, best to use same lead (spec) as repair, which will be lead flashing material.

 

[chunkolini]

Problem with Oxy acetylene is he will be up on top of a roof.

Chunko'.

 

[madkayaker]

long hoses or portapack? or bottles in house upstairs and hoses out of window?

 

[Robotstar5]

Problem with Oxy acetylene is he will be up on top of a roof.

Chunko'.

PortaPak or long hoses?

edit : never try to beat MK!

 

[madkayaker]

don't do problems do solutions!

 

[Jaeger_S2k]

I would have thought a MAPP gas torch would be hot enough and easy portable.
MUST be super clean and gleaming. If it's a strip split (not a large gap to fill) I'd be tempted to use a sweating rod (Lead block of solder) we used to use for sweating copper to lead. Shouldn't need flux if it's clean enough. I suppose melting lead to lead is an option but it'll be more difficult than lead solder stick.

 

[drivewasher]

????? No Flux??

I have done loadsa plumbing and always use flux on lead joints, although not many about now

Also in regard to the orig post can he not use pre-glued /self adhesive lead flashbanding. If all old lead is cleaned up then should be ok, warm it up as you do it to aid sticking

 

[Jaeger_S2k]

Lead to lead would be fine without flux and it's not under any pressure. If I was sweating lead to copper for water or gas (last one was about 18 years ago now) then yes flux.

 

[runnach]

Plumbing apprentices use our oxy-acet area for lead burning as their trade seems to call it, I've viewed some cracking pieces of fabbed up leadwork being welded, not a drop of flux to be seen, no idea why???

 

[piman]

Hello all,

no flux for welding but flux for soldering, usually tallow?.

I would go for soldering rather than welding seeing as it is in situ on a roof, unless he can bring the section down if it is practical to remove it completely?

Alec

 

[bob the builder]

As a time served plumber I would use grade D plumbers solder clean the area until the lead is bright use flux, heat the lead and solder, lay on a good amount of solder if you get the heat right you can get the solder to a putty like state at this stage you should be able to use a cloth and wipe the solder to shape.

 

[runnach]

As a time served plumber I would use grade D plumbers solder clean the area until the lead is bright use flux, heat the lead and solder, lay on a good amount of solder if you get the heat right you can get the solder to a putty like state at this stage you should be able to use a cloth and wipe the solder to shape.

That is interesting Bob. As mentioned above, I have viewed plumber apps lead burning, no flux used, I'll pose this to their lecturer tomorrow, I'm curious now.

Cheers..........

 

[bob the builder]

Lead burning no flux, soldering use flux, they are two very different processes, just one more point if the lead has weathered very thin it would be impossible to lead burn.

 

[steve nunn]

Do the lead welding/ burning as runnach says. You heat the metal up until it starts to go shiny and then keeping the heat on the metal (but only just to keep it at the shiny state) you start to melt the filler until it melts and drops onto the lead to be 'welded', you end up with a weld that looks like a tig weld.

Use a reall small nozzle, a micro nozzle i think theyre called. And let the lead filler drop onto the metal a drop at a time and move along like that.

Its a while since ive done it, scraping the metal until shiny is a must. No need for flux. As for mac gas burners, ive never tried it, always done it with oxy acetelene, not sure a blow torch would give you a small enough flame and still get the heat across. But give it a try, it might work, ive just never seen it done using that, always seen it and done it with oxy acetelene

steve