Connecting to a salt-glazed drain with plastic.

[brucek]

Hi all. We're moving our kitchen and bathroom so I need to join a new 110mm plastic pipe run into an existing salt-glazed pipe run, which falls quite steeply. I can't find a suitably-sized salt-glazed 45 degree junction so it looks like I will need to use a plastic one with flexible couplers at each end. The old salt-glazed pipe has an outside diameter of 200mm (old 8") so I'm presuming the inside diameter will be something like 165mm to 175mm, though I can't cut through it beforehand to check/measure because the system serves other users. Should I buy a 200mm x 200mm x110 plastic junction or a 160mm x 160mm x 110mm? They seem to be the only sizes available. I'm a bit hesitant because I don't want to reduce the flow capacity of the existing set up but also I'm concerned that creating a ridge at the bottom end of the junction where it joins back into the salt-glazed pipe might cause future blockages. Advice from the wise would be much appreciated. Thankyou.

 

[Bonni]

The internal diameter is the important part. You can buy rubber couplers that have a large jubilee band at each end. So you need one to go from plastic to salt glaze. If you join any combination of plastic, super sleeve, and salt glaze to one another, just make sure everything is cut accurately so the 4" internal diameter part is aligned up as smooth as you can with no gaps because the waste water and solids need to flow through without snagging. Unfortunately, sometimes you have to dig along to get a better cut on the salt glaze pipe.