50 Cast to 40 Plastic Adaptor

[Benarty]

Hi,

I have a 50mm cast iron tee coming into my kitchen from the cast iron soil pipe and I am refurbishing the kitchen. The old plastic pipe was pushed inside the cast by about 300mm and was gunged up with something, probably hemp and boss white. When I tried to connect a compression fitting to the other end of the plastic pipe, the connection to the cast tee moved and turned so I tried to redo the joint with PTFE tape, Plumbers Mait and some silicone. I tried a water test and there was a minute leak from the joint when I inspected it after about one hour. The problem is that there is no mechanical pressure on the joint and it could get worse.

This joint is inaccessible once the new kitchen units and worktops are fitted so I need it to be 100% leak free. Is there an adaptor to make this connection? I have tried about eight local plumbers and builders merchants to no avail. The OD of the cast is 60mm. Any advice would be much appreciated.

Ben

 

[crockett]

Ben, I have in the past ground down the outer diameter of the cast iron pipe to fit a 2" compression fitting. It's time consuming, but it is possible.

 

[Benarty]

Yes, hadn't thought of that one!

If nothing better comes up I may try that! There is an Osma reducer which will take, about 55mm OD to 40mm plastic available with a rubber collar so that would be very little grinding down to get the Osma collar over the cast.

Ben

 

[Benarty]

Just thinking I could still do a gunged up PTFE tape, Plumbers Mait, silicone connection and then put the Osma collar over the lot for a belt and braces joint.

Ben

 

[Hugh Jaleak]

Flexseal coupling might do the job. http://www.flexseal.co.uk/index.php

 

[kirkgas]

google mcalpine plumbing and search for a "caulking ferrule" (code T21A, 2" x 38mm) this is designed to go inside a CI faucet, it has a lip on the end so that when you put the rope in it doesnt fall right into the joint, i would use plumbers mait on the joint, after packing in plenty of either rope or the poly bag that the fitting came in, if you can get it 100% bone dry some people will use silicone, it will never leak if made properly