Connecting waste pipes to cast iron main soil pipe

[Si5584]

Okay so where to start….

The attached picture shows my starting point, i am replacing the piping for my bathroom suite (which is also getting replaced) however i am struggling to connect to the cast iron soil pipe.

I asked elsewhere for advice and was advised to get 40mm (upper) and 32mm (lower) rubber boss connectors for the upper and lower connections which seemed to make sense however after purchasing i realised that these are no good they are bigger than the openings also. I also can’t seem to simply fit the replacement pvc pipes directly in as they are too large.

The original pipe outer diameters are:
Upper pipe (sink waste) : 40.7mm
Lower pipe (bath waste) : 34.5mm

New pvc sealant pipe:
Upper pipe (sink waste) : 43mm
Lower pipe (bath waste) : 36mm

I am now stuck with what to do.

I also ordered a mcalpine macfit mac-1 for the toilet wast connection however this seems just too big and i’m not sure a mac-3 will be big enough.

I should also say i have pulled all of the current piping shown in the image out. All that is left is the main cast iron soil pipe.

 

[Madrab]

The cast sockets for the pan connector would usually take a 31/2" soil pipe adapter, that being said it may need a bit of help with a silicone polymer adhesive - like wet grab - to seal it properly.

The waste pipe sizes would have been sized originally to take iron or copper waste pipe, all imperial sizes so you may have to adapt modern equivalents to take new waste pipes. Again it may need the same silicone adhesives to set the adapters in.

Just make sure everything is super clean and dry, use a grind stone or flap wheel to buzz up the internal faces to get them as rust free and as shiny as possible. Coat the inside with a thin coat of adhesive and let it dry to give the best key.

The upper pipe size would be 11/2" lower would be 11/4" (bit small for a bath mind you). If you get size up push fit (PP/PB) pipe you will find the OD smaller than ABS solvent weld - 32mm is usually just over 33mm OD and 40mm is about 41mm OD as against 36mm and 43mm for solvent weld. That'll be why it has compression elbows in the pic as push fit will normally fit them.