Joining plastic sink waste to cast iron?

[newman]

I have had to renew my sink waste in 40mm plastic pipe. What is the best method of sealing this to an external 3in cast iron pipe? At the moment the plastic is pushed about 300mm into the cast iron pipe which runs at a 20 degree fall.

Regards

[Michael Mcneil]

What is the problem?

Presumably you have a trap below the sink to stop odours coming up the spout?

[newman]

coming back up, as the pipe is beside my patio.

Regards

[fred]

In article , newman writes

A rubber adaptor is probably as good as anything:

, code 11228 (£7+vat+post) (near the bottom) looks like it would do the job. You could use a plastic adaptor to beef up the size of the 40mm pipe if the rubber adaptor won't go that small: code 12993 for solvent or

12987 universal (again near the bottom of the page).

Local plumbers' merchant will prob have them too if you want to save post.

[newman]

Thanks, but there is no room to fit an adapter as the 90deg bend of the

40mm plastic pipe is about an inch from the cast iron pipe. I may need to use plumbers mate or similar.

Regards

[fred]

Oh ffs, nothing like getting the full story in one hit :-!

Ok, how long is the 3" pipe, just a socket into a branch or a long length (cut end or socket). If a long length, do you mind cutting it back or is it supported at the end. Any more info would be great.

Oh, is the 90deg bend on the 40mm removable, if not and you're not prepared to remake it then you won't be able to use any kind of adaptor.

[newman]

The cast iron pipe is fixed to the wall and I dont want to move it. The plastic pipe comes out of the wall and turns 90deg into the cast socket . Yes I can take the 90deg off but there is only about 1" between it and the cast iron socket.

Regards

[Michael Mcneil]

Half a tube of the sort of silicon sealant that can be used under water. Either that or some foam spray.

[newman]

tight push fit about an inch into the cast iron. I then filled the remaining gap with plumbers mate and painted. I looks ok and should prevent smells etc.

Thanks for the other suggestions.

Regards