Drilling a cast iron soil pipe

[denso13]

The material seems to be massively harder.

Soil pipe can be heavy grade and come substantially thicker that cast iron rainwater pipe.

You maybe, unluckily, have both and found the first one easier.

 

[dilalio]

Its fine to put it into cast as long as its in the wet bit ie it can't be the top connection to the stack.

As long as you have a bath, basin or wc above it there's no problem

Fitted a ravenheat to a 5 storey cast iron stack... Put the condensate so it went into the sink and was diluted by the hot water... No heating. So I did it but at the time thought it could be questioned

 

[endecotp]

Soil pipe can be heavy grade and come substantially thicker that cast iron rainwater pipe.

Right; I don't think this is heavy-grade and I guess that now I have a hole I can measure the thickness.

 

[endecotp]

Its fine to put it into cast as long as its in the wet bit ie it can't be the top connection to the stack.

Right, I found a Worcester Bosch note saying exactly that. I only need to worry if all the upstairs flats are empty - which is unlikely, but not impossible.

 

[Justin Passing]

CI hardness varies a lot out of the factory.
HSS will always cut it - the CI softens and the HSS doesn't, if you go fast/hot enough. That's the point of HSS.
One thing I've found common to those plastic-to-CI fittings doesn't vary though, they all leak. The water rusts the iron and it runs down the pipe. I'd scrape the paint off and put some sealant in there regardless what they say.
YMMV, I guess!
If you download the picture of that fitting it says there's a fitting tool. I'm not familiar with that afai can remember, and I can't understand it from the diagram. There are two parts, but the curve's the wrong way, at first sight.

 

[endecotp]

Believe me [the TCT hole saw will] fly through that, hardened or no.

And without increasing the danger of cracking the pipe?

Remember the initial question was "how can I drill a cast iron pipe without it cracking?", not "can I drill a cast iron pipe at all?". Hence going slowly, using lubrication, etc.

 

[endecotp]

CI hardness varies a lot out of the factory.
HSS will always cut it - the CI softens and the HSS doesn't, if you go fast/hot enough. That's the point of HSS.

So you reckon I should be drilling relatively fast?

One thing I've found common to those plastic-to-CI fittings doesn't vary though, they all leak. The water rusts the iron and it runs down the pipe. I'd scrape the paint off and put some sealant in there regardless what they say.

Right, maybe we'll discuss that once I reach that point!

If you download the picture of that fitting it says there's a fitting tool. I'm not familiar with that afai can remember, and I can't understand it from the diagram. There are two parts, but the curve's the wrong way, at first sight.

Yes, it's not completely obvious but the diagram is right. Basically there are some teeth that pop through the pipe and a piece inside that is tightened back towards the wall of the pipe to hold the teeth in place.

 

[trojanhawrs]

And without increasing the danger of cracking the pipe?

Remember the initial question was "how can I drill a cast iron pipe without it cracking?", not "can I drill a cast iron pipe at all?". Hence going slowly, using lubrication, etc.

I don't see why it would crack, you might be able to crack thin cast by lumping it with a hammer but I wouldn't expect it to crack from a small hole even if the saw bites, but you could turn down the torque to be sure

CI hardness varies a lot out of the factory.
HSS will always cut it - the CI softens and the HSS doesn't, if you go fast/hot enough. That's the point of HSS.

That's nonsense.

 

[Justin Passing]

That's nonsense.

Nope, look it up.

 

[endecotp]

This saga is nearly over. I have learned some new things, which is always good, isn’t it?

Last time I posted I was going to get a TCT hole saw. But I managed to click the wrong button and ordered a 20mm one instead of 22mm. By that time the heating engineers had arrived to fit the new boiler.

Of the plumbers and plumber-adjacent people I’ve spoken to about this there has been a stark divide by age, Everyone under about 50 says “oh no it will crack - disaster don’t do it!”. Everyone over 50 says “OK, use a conical step drill”.

The guys who came to fit the boiler were about 25 and 65. The older guy gave the younger one the step drill and told him to get on with it (in the hole I had started). It was quite quick, nothing cracked, and we ended up with just the right sort of hole.

One thing I've found common to those plastic-to-CI fittings doesn't vary though, they all leak.

So now we come to this……

They fitted it wrongly but with a load of leak sealant to attach it to the pipe. It ****ed all over the place. I dismantled it and re-did it per the instructions, and now I have drips from the bottom corners. I guess I need to seal it somehow.

It comes with a soft pad that fits between the boss and the pipe. I’m wondering whether I should remove that and apply a generous layer of sealant to fill all that space, or whether I should add sealant as well as the pad, or what. Any ideas? I have an open cartridge of black OB1 that I guess would be suitable?

 

[Madrab]

Just get a little silicone adhesive in there, yeah the OB1 should do the job. Dry it all out thoroughly and no need to be excessive, just enough to have is squeeze out a little at the gaps and then smooth it over. Ideally let it set for a while, before any fluid is run through it.