Tapping PVC waste into an existing cast waste

[honestinjun]

I need some advice on the best way to join into an existing cast iron waste pipe that runs just off the horizontal along the inside of the eaves of the house.

I tried to use an existing angled tee (excuse the guesswork on some of the terminology) which has a lead spigot on a bulb shaped adapter that fits the cast iron socket. This was already fitted for the previous 1 1/2" PVC pipe. I have struggled with this on 2 fronts. The spigot angle was slightly too steep for my new PVC pipe and the resulting pressure exerted on the 40mm adapter I was trying to use prevented me getting a watertight joint. The second issue is that there is an additional tee downstream of this one which I no longer require but do not know how to block it off. I tried unsuccesfully to simply fill it with silicon but it did not grip sufficiently well and I am reluctant with this solution as I also feel this tee disrupts the flow from the one immediately upstream of it.

I either need to know how to deal effectively with a slight change in angle as the PVC joins the lead spigot and how to seal an angled cast iron tee that no longer attaches to anything or whether I should simply cut the cast iron below the second tee and bring my new PVC down to a point further downstream.

The latter sounds more brutal but probably cleaner assuming there are products around that make it fairly simple to cap an open cast iron pipe while providing an tee to accept 40mm PVC but I am concerned that I turn this into a fairly major task just because I cannot overcome a couple of seemingly simple issues.

Any help gratefully received.

 

[Rodreguez]

i usually cut the stack down fit a flange go into pvc renew the lot but others may tell you a way to keep the cast stack.

 

[justlead1]

Hi. With the waste. Why not warm the pipe and form a bend to the fixed angle you are connecting to? As for the cast iron (i am assuming its a socket) If time allows, knock up a bit of sharp sand and cement, find a bit of plastic pipe with an inside dia. a bit smaller than CI. socket.
Use the pipe as a shuttering when dry, using yarn or rope caulk it in the socket and fill the last inch with wet cement and smooth off. If pushed for time purchase a black iron or galv socket and plug and caulk that in. Good Luck

 

[honestinjun]

Thought I would add a photo (taken from above) altho from your comments I think you understand what I am trying to do. What does the flange do? Is it an adapter and how is it connected to the cast and PVC?
Cheers.

 

[Rodreguez]

flange goes over each pipe with jubilee clips looks ugly but if hidden away won't matter.

 

[honestinjun]

Suspect you are talking about taking it back to the vertical? Does the flange work ok on a horizontal pipe?
Cheers.

 

[honestinjun]

Good advice on the use of a cement plug - hopefully this will limit the amount of interference on the flow past the tee.

I am a bit reluctant to bend the spigot and use the lead to 40mm PVC adapter. The lead is not in great shape and even if I take the pressure off the join by aligning it better, I am not convinced I can make it watertight. I have tried this and can sometimes make the join watertight by rotating the adapter until I hit a "good fit" position but it is not stable and eventually weeps. Any suggestions on how to deal with an imperfect pipe? Would silicon within the compression joint deal with the scores and gaps? Alternatively is there a way to to completely remove the lead spigot and put PVC into the angled tee?

Thanks.

 

[Rodreguez]

Suspect you are talking about taking it back to the vertical? Does the flange work ok on a horizontal pipe?
Cheers.

i can't see any reason wht it shouldn't seal on the horizontal!

 

[justlead1]

Hi. To cap of redundant waste, just tap lead to a dome and wipe a bit of solder over end. Branch you wish to use, cut through the lead/bush flush with CI. (the bore may except pipe? If not use a metal cutting blade in a jig saw and cut 3 or 4 slits in the bush and remove pieces with and old screw driver or alike. Use 11/2" socket and threaded plastic adapter to connect.

 

[honestinjun]

Advice all good and allowed me to seal the unused socket fine. Also heated the lead spigot and bent to match the angle of new PVC waste and this proved much more reliable. Now however having disturbed the lead/cast I have a very (and I mean very) slight leak at the original joint of lead spigot and cast socket.

Any suggestions on an easier answer than removing the whole thing and replacing with a rubber or plastic adapter? i.e. can I heat the lead and rework it and if so do I need anything other than a torch and mallet?

 

[justlead1]

Hi You can try caulking the joint if its has a lead run joint into the cast iron socket. Use a blunt cold chisel just to drive in the lead with taps of the hammer, dont go mad, and this expands it to seal the joint. If you use a flame and get to ambitious it may end in tears as the lead/solder wiped joint may fail.