[gmason]

I have a 1.5" lead stub to a cast iron waste pipe in a 1912 house. I am replacing all the drain pipe that leads into that stub. I find that a 1.5" PVC pipe slides over the lead and makes a pretty good slide fit. I plan to run a 45 degree fitting from the stub and go from there.

My question is this: if I cement a 1.5" PVC stub to the PVC 45, and slip that PVC stub over the lead for several inches, can I use liquid rubber, rubber cement, epoxy, or anything else to seal the space between the sleeved pipes? My guess is that the space between is around 1/32". In any event, I plan to use a rubber coupling with clamps to span the joint - part over the PVC and part over the lead, but I thought filling the space would also help in the long run.

[Milo Dolezal]

You have to use a coupling to connect PVC and Lead pipe. Use Fernco or Mission or Flex seal coupling to connect those two. Home Depot sells 1 1/2" x 1 1/2" Flex Seal coupling for under $5.00. See the image...

[gmason]

Hmmm... I added a response yesterday, but it vanished. So...

I have/know that, and will certainly do it. In fact, 1 1/2" to 1 1/4" is the right size.

The question is (belt and suspenders) whether there is something I can use between the sleeved pipes to add leak security. I am pretty much decided on a silicone sealant, but other suggestions are welcomed.

[KISS]

On the PVC side, I wouldn't use anything but plumber's grease.

If the lead side is smooth, then plumber's grease as well.

If not, use something like "form a gasket" that's found in auto stores.

[gmason]

On the PVC side, I wouldn't use anything but plumber's grease.

If the lead side is smooth, then plumber's grease as well.

If not, use something like "form a gasket" that's found in auto stores.

I am a little confused by this. It sounds as though if the lead is not smooth, there would be two different things used - plumbers grease on the PVC and liquid gasket material on the lead. But since the PVC slips over (sleeves) the lead, making a pipe inside a pipe, that is confusing to me. Please explain.

Thanks!

[massplumber2008]

Hi all:

I just wanted to pop in and set the record straight on this topic for future readers... OK?

I've been working with lead pipes for 30 years now and you do NOT need any sealants, grease or any silicone if you use the correct clamp to connect the pipes. Further, you don't insert the lead pipe into the PVC pipe... just not done that way. It isn't that it is a bad idea, but more so that it simply isn't needed!

Now, plumber's grease can be used IF the clamp won't slide onto the PVC pipe, but here we are only talking about 1.5" PVC pipe... no need for grease here... clamp simply slips on with little to no resistance.

In terms of the lead pipe they are almost ALWAYS smooth unless you are trying to connect onto the brass ferrule near the cast iron stack... that can be rough, but even here you would melt the old lead off the ferrule and clamp directly to the brass fitting.

Anyway, ideally you would eliminate the lead all the way back to the cast iron or the brass ferrule, but if that won't work here purchase an 1.25" x 1.5" shielded transition clamp similar to the clamp Milo posted and secure it properly to the pipe ends and you will be fine without any additional "stuff"... I PROMISE!

Any questions let us know... OK?

Mark

[gmason]

Thanks - that is good info. I am sleeving simply for strength - not just rubber alone.

[ritzco]

There remains the question of what is the best glue lead/pvc. Whether it's necessary or not. Anybody know?

[massplumber2008]

Ritzco

There is no "best glue" for this application.. period! There is only right or wrong and anything but a tight seal between a pipe and a clamp is wrong. Make sense?

[Milo Dolezal]

I fully agree with Mark's statement. Personally, I don't think I know a "glue" that would be Code approved to connect metal pipe with plastic pipe. As Mark indicated 5 years ago in this thread, we also use special rubber couplings designed to connect the two.

Milo