undoing cast iron soil pipe joint

Folks,
I wish to separate two sections of a cast iron soil pipe, which appear to have been socket joined using (lead?) solder, covered by bitchemen (which I have chipped away).
Is there any technique to break this at the joint, or is my only option to cut the iron pipe and then fix a plastic pipe to the stub?
I don't want to just try to melt the solder with a blow-torch due to: 1) fear of soil gas explosion - is this founded? 2) fear of setting light to the 40 year old dust on the other side of the partition wall 1 cm behind the joint.
I've tried to illustrate below. What I want to do is remove pipe B, and replace it with a plastic pipe, as this will give me more flexibility as I need to move the WC. In fact pipe A and B are slightly angled, but I couldn't show that with my ASCII art!.
(I'm in London W5 if it will require a professional job and anyone can recommend a good plumber)
+ <-thin partition wall + : c : + : o : + : m : + : u : + : n : + : u : + : a : + : l : + **** ===: :********* ==========: s pipe A pipe B <- WC connects here : o :********* ==========: i : + **** ===: l : + : : + + +
Thanks,
Alasdair
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Two techniques were used for cast iron socket joints:
a/ pack with a hemp grommet (to make solder proof and central, pour lead in using a clay mould or direct if vertical
b/ pack with lead foil and hammer home.
With the b/ technique it can be unpicked with care, stating by screwing in a wood screw and pulling on it, but this doesn't work with the a/ method. With GREAT care it can be cut out using a very narrow wood chisel but it is very difficult to get right down to the bottom of the joint and remove material (particlarly if you are up a ladder !!!). If the joint can be laid down the lead can be melted out but be sure to gently warm the c.i. or you will crack it
Andrew Mawson
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I agree with Andrew but suspect in this case the right option would be to lose the accessible bit of iron and replace with plastic. Probably start with an angle grinder. I've used the little slitting wheels on "dremel" type tools to slit the remains of the inner tube without threatening the socket, or just to put in a stress raiser so that it cracks without applying too much force.
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snipped-for-privacy@aol.com (OldScrawn) wrote in message

Thanks for that. A further question.
I don't think the cast iron pipe is 4". I appears to have an external diameter very similar to the internal diamaeter of the 110mm plastic pipe.
Whats the best way to make the connection? Perhaps I need an adaptor that will smoothly reduce the 110, and fit internally to the cast iron pipe? or can I just slip the plastic pipe over the cast iron stub and seal it up?
Also, is the cast iron likely to be a 3.5" internal diameter? Its marked with a "C" if that is of any use!
Thanks,
Alasdair
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to lose

an
tools to

just to

force.
If the 110mm diameter is at the spigot on the end, then pipe is classed as three inch. There is no way you get a 110mm (4'') pipe into it, or an adaptor that goes the wrong way round, i.e. 4'' on top to 3'' on the bottom. Although there are reducers that will go from 3'' above to 4'' underneath.
(see below)

What are you connecting to the stack ? What is already connected to the stack ?
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Hopefully the below ascii picture will explain. + <-thin partition wall + : c : + : o : + : m : + : u : + : n : + : u : + : a : + : l : + **** ===: :********* ==========: s pipe A pipe B <- WC connects here : o :********* ==========: i : + **** ===: l : + : : + + + I am on the ground floor, the communual soil is vertical and pipes A and B are just off horizontal..
I want to remove pipe B from Pipe A, and replace Pipe B with a new plastic one.
Pipe B: Cast Iron ~110mm External diameter along its main length (The socket at the end is much wider and accepts the WC) Unknowen internal diameter. Marked with the "C".
The question is, how best do I attach the 110mm plastic pipe to pipe A.
Options seem to be. 1) Cut Pipe B in half and graft a new plastic pipe to the Stub. 2) Dig out the lead fixing pipe B into Pipe A, remove pipe B and and fit the new pipe into the socket.
for 1), The question is, is this a wise thing to do, and if it is, how exactly should I form the join?
for 2), having had a look there are about 4cm of lead to dig out, so that's very hard in its self, and then the question is again, how exactly to make the join?
Any help on this is very much appricated. I'm not absolutly opposed to getting a professional plumber in if thats required, but I'd rather crack it my self.
Thanks,
Alasdair
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Right, once you get everything ready you tell the neighbours what you're doing and not to use the loo as you do the job, or you'll end up with jobs on your toilet floor.
You need to free the spigot of the bend into the wall. The stone/brickwork around it should be large enough to allow you to make quite a big hole through the wall. Keep all the big bits that come out of the wall so you can use them again to fill the hole back in when you're done.
Once you get the spigot cleared you'll find it easy enough to waggle around the pipe that's atached to it. The waggling around will ease the lead joint but it has to be done firmly but gently so that the pipe begins to move freely but doesn't break the sides of the old spigot, so move it little bits at a time with your hands and don't bash it about with hammers and things.
When the pipe is moving quite freely you should find it easy to get a narrow chisel in the joint to dig the lead out. It takes a bit of patience and a lot of jabbing with the chisel for the first ten minutes or so until you see any great progress, but stick with it for this time and you'll be able to remove the pipe in one go and keep it in one piece.
Every time you chip a load of lead out, waggle the pipe around in a circle again until the pipe gets looser and looser. The lead wil get easier and easier to remove the more you do this. When you get down to rope caulking is the time when the pipe will lift in one whole piece. Remember to waggle the pipe firmly but gently and don't move it huge distance or you'll break the sides off the spigot.
When you get the caulking rope is the time you go tell the neighbours not to use their loo while remove the old pipe and install the new one. Once you have the new pipe in place you ca nuse the old caulking rope to wrap around the pipe and press it down into the spigot to keep the new plastic pipe in the centre of the spigot end. Whe nthe pipe is firmed in with rope you can fill the spigot with a sand and cement mixture and support it until it dries out and goes solid. Or you can fill the joint with silicone sealant from the gun type tubes you can buy. This too needs to be supported until it cures off and this can, in both cases, take up to 24 hours.
Keep the end of the pipe that stick into the room covered with a damp cloth or jam it with screwed up newspaper to keep the smells out of you house and allow your neighbours to use the loo again without stinking your home out with last night curry.
Because you're on the ground floor of this building, you should be able to do this job in a couple of hours from start to the point where you're letting the pipe joint set hard and everyone above using their loo again.
Tools needed:
Hammer and brick bolster (to remove the stone, mortar fro maround the spigot in the wall) Narrow wood chisel 1/4'' (under 10mm wide that you'll never use again on wood, so get a really cheap one just for this job) Tube of silicone sealant or gutter seal and an applicator gun Any other tools needed to remove things from around the inside where the pipe is
Please don't try to use the lead again because when it's hot it melts its way through the plastic pipe quite easily. :-))
Good luck with it.
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Thanks for your effort typing that in. Really aprriacteded. To make sure I understand what you said, I've got a few clarifcations below.

Am I correct in thinking: Spigot: The main shaft of pipe B. Bend: This is just the socket that I can see protruding through the wall (Pipe A).

I'm not sure where the wall comes in. As I understand it, the socket that will be remaining (pipe A) will not be moveing, and the socket end (i.e. the union between pipe A and pipe B) is clear of the wall, so I can't see where the wall comes in. Perhaps there is something I'm missing.

Infact its just a 9mm ply 'wall' with a few wooden battons. Its just there to cover up the pipework.

Nots sure I get this, maybe I've misunderstood spigot. Basically, the union between pipe A and pipe B is on my side of the wall and 'clear' of the wall. I have also (previously) removed the WC from pipe B, and pipe B seems absolutly solid in pipe A.

OK. Can I tap it with a rubber mallot. The lead is pretty damned hard, not sure if just my hand-force will make much impression.

OK, I can just about get a 3mm drill into the lead, down to some fiber (presuably the rope), the lead is about 4 cm deep!. Using this I've managed to dig out a hole the size of a french been!
The socket appears to be tapered (i.e. wider at the open end, then tapers in). This lookes like it was filled with molten lead. Looking at it, I'd be surprised if anything would move before I have got out a lot more lead out.
Getting just a 5mm 'french been' hole in it took a couple of hours, access and angles are pretty poor.

OK
Can't seem to get any movement so far, but I guess if I can take out some lead it will get better.

Thanks again. clarification of the above points would be most useful. - check I'm not completely going off in the wrong direction!
Thanks
Alasdair
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The spigot is the bit on the end of the pipe that accepts the plain end of the other pipe you want to join to it. The female part as opposed to the male part.
If you can see the spigot of the pipe that enters through the wall, then you can get the job done. If you can't, then you're going to have to cut cast iron pipe with a cutting wheel and angle grinder.
Working from the spigot joints makes doing alterations on cast pipe much easier, so it's why I said work on the spigot and add another section of pipe (plastic or cast iron) to it and it makes life a lot easier.
You say you're on the ground floor, so getting at both the inside and outside sections of pipe should be quite easy for you, and I just wish that we lived on the ground floor of our place so I could have saved money on scaffolding for a weeks hire. :-))
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