Thread: Connecting PVC to clay waste pipe

Hi guys,

i have just installed a new bathtub and new waste pipe which is 40mm PVC, It goes into a 150mm dia clay pipe in the ground.

What is the best way to seal up the connection? i plan on mortaring in up, but are there any tips to doing it, as i am worreid the mortar will drop into the clay pipe and clog it up while it is still wet.

The 40mm pvc is not centred in the clay pipe.

thank you in advance

I am not a plumber but I think the is a specific fitting to do that

In the old days... use scrunched up newspaper packed in between the two. This stops the mortar from falling in until it goes off. Over time the newspaper will rot but not block the pipe.

HI,

There is an adaptor to convert from clay to pvc, however the pipe will still be the same size. You would also need a reducer to take it down to 40mm.

The fitting I'm referring to looks similar to a pvc slip joiner with a chunky o ring in one end - pretty sure iplex make them.

Hope this is helpful.

Originally Posted by inferno6688

Hi guys,

i have just installed a new bathtub and new waste pipe which is 40mm PVC, It goes into a 150mm dia clay pipe in the ground.

What is the best way to seal up the connection? i plan on mortaring in up, but are there any tips to doing it, as i am worreid the mortar will drop into the clay pipe and clog it up while it is still wet.

The 40mm pvc is not centred in the clay pipe.

thank you in advance

Ummm, I don't like the sound of this.

Originally Posted by Eastwing

Ummm, I don't like the sound of this.

Ummm, whats up?

the only problem i see with the proper joiner is that the 40mm doesn't sit centred to the clay pipe, so it may not work.

what part don't u like the sound off? i can't really change the clay pipe, as its the original buried pipe of the old house.

You need something like this, attached. The example is for storm water

Use a ceramic disc on your angle grinder to cut a good flat end on your clay pipe, no cracks.

I'm sure these couplers come in different sizes and reductions. The rubber is quite flexible, and so you may be able to manage with your non-centred PVC, but failing that, cut it back and add an angle piece to help centre it.

I believe they are called fernco fittings.

Also sold as Ozi-mate connectors. Best way to do this is to cut the pipe back install an Ozi-mate / Fernco and fit a PVC reducing collar to the 40mm pipe. The reducing collars to adapt it down are usually offset so it doesnt matter if its not centred.
Alternatively if you mortar it, make the mix a bit drier and a bit stiffer than you would normally and when it goes off silicon around the PVC.

Originally Posted by olfella

In the old days... use scrunched up newspaper packed in between the two. This stops the mortar from falling in until it goes off. Over time the newspaper will rot but not block the pipe.

My plumber did that

Sit it in, pack it with newspaper and cement it up, easy.
Or, if the earthenware collar is still intact, make a flat cover out of lead or a bit of villa board that will sit inside the collar with a hole in it for the 40mm then fill the collar with sand and cement. This will be the best way.

thanks guys,

will try the villa baord idea, otherwise i will just use the news paper packing idea

The only problem with cement is that it cracks and this provides an entry point for tree and plant roots and hence you have created a never-ending problem.
I used the rubber ring thing - really it is the only way. Available from plumbing supply specialists - Do not think the DYI hardware stores have them. The plastic sleeve is an over-sized collar made the correct size to accept the ring. Takes some force to push it on (the ring sort-of rolls onto the pipe and up the sleeve as you push) but once on, it is sealed.
Cut the pipe first as described.
Use a reducing collar as mentioned to reduce down to 40mm.

Originally Posted by bookleaf

The only problem with cement is that it cracks and this provides an entry point for tree and plant roots and hence you have created a never-ending problem.
I used the rubber ring thing - really it is the only way. Available from plumbing supply specialists - Do not think the DYI hardware stores have them. The plastic sleeve is an over-sized collar made the correct size to accept the ring. Takes some force to push it on (the ring sort-of rolls onto the pipe and up the sleeve as you push) but once on, it is sealed.
Cut the pipe first as described.
Use a reducing collar as mentioned to reduce down to 40mm.

Rubber Vs cement? I'll choose cement, thanks.

Have been there. My house has earthernware grey water pipe buried under the verandah slab. The PVC fittings mentioned are as far as I was aware, meant to be cemented in place after to prevent movement. They are not easy to fit. You need to use lubicant. Petrolium Jelly or the like. With earthernware pipe there is always the risk of too much force and breaking them. I like to clean with a grinder and seal with silastic, then secure to prevent movement in future. I would replace all earthernware if possible. It is now old and brittle. What the pvc will be in 50 years i imagine.

I have a stand alone septic for the toilet and seperate grey water (50 years old) system. Neither connected to any public utility so not much interference from you know who. Same with my water. Dam and rain water. All supplied from my own storage, with my own pumps, storage tanks and so I can pretty much do anything I want.

Dean

I fogot to mention in my previous post that the most important thing in my opinion is that you seal the joint and prevent movement completely. Even cement on its own will not stop roots from invading if they can find the slightest moisture. Go with cement by all means but the cement is to prevent movement, not to seal the pipes. Use silastic first. Earthernware pipe is porous except for the glazed inner and outer surfaces so seal to these with the silastic.

Rubber Vs cement? I'll choose cement, thanks.

Dean

Only the older SGW (salt glazed ware) was as you said glazed, and this was sealed with cement. The newer VCP (vitrified clay pipe) was not glazed, how ever its density ensures that it won't soak through, and this was sealed with rubber rings that over time perished, went brittle and let the roots in. In my experience silicone doesn't hold to earthenware pipe.

Originally Posted by wonderplumb

Only the older SGW (salt glazed ware) was as you said glazed, and this was sealed with cement. The newer VCP (vitrified clay pipe) was not glazed, how ever its density ensures that it won't soak through, and this was sealed with rubber rings that over time perished, went brittle and let the roots in. In my experience silicone doesn't hold to earthenware pipe.

I am no plumber and my experience is only from working on my own houses. Two to this point in time and both had glazed pipes. If what you said is correct then that just about wipes out all options because there are installations out there that cannot be changed for PVC without incurring vast cost. I use silastic and then cement (lots) to seal these joints. As I have said before moisture is the problem. If plants cannot sense moisture they wont invade. I have lost count of the number of joins I have removed masses of roots from then sealed with silastic and cement. All the accesible stuff has now been replaced with PVC.

I agree that none of these option are perfect. My current earthernware pipe is buried under about 24m of concrete floor, verandah etc. I have thought of every thing I could to replace it but money is the problem.

Another name for the rubber fitting is Plumb quik

They are not easy to fit. You need to use lubicant. Petrolium Jelly or the like.

Don't use petroleum jelly to lubricate rubber or pvc fittings. It can cause deterioration of rubber over time. Better to use liquid soap or detergent, this will also completely wash away.

Originally Posted by rcgrimmer

Don't use petroleum jelly to lubricate rubber or pvc fittings. It can cause deterioration of rubber over time. Better to use liquid soap or detergent, this will also completely wash away.

Good Idea. I hope never to have to use it. We use dishwashing liquid at work to fit 2" and 3" hoses to stainless tails before clamping.

Dean