Help needed with cast iron vertical toilet stack

[gaswizzard]

Have you checked for clearance at rear of pan for flush pipe?

That looks like a salt glazed collar , the thickness gives it away , inserting a fitting into the pipe may lead to blockages due to the sharp turn.

 

[Nige F]

Finally, I would imagine cutting iron with an angle grinder is going to produce lots of sparks.. is their an alternative??

I very much doubt I would undertake such a task, but good to be armed with info when Im talking through what needs doing with someone...

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As to cast or clay - try it with a magnet I`m with cast . And I would drill loads of holes vertically round the flange near to the pipe - new high speed twist drills and a non hammer drill - then break out the socket with a sharp cold chisel and a lump hammer . You wouldn`t need to talk me through it , just make loads of tea and provide chocolate digestives I`m not frightened of a bit of cast drainage , but I`m wary of disc cutters