Joining new soil pipe to old

[Penners]

Has anyone ever had occasion to join new 110mm plastic above-ground soil pipe to an old soil stack? I have to do this, and I'm a little unsure about the relative internal diameters of the old and new fittings.

The old stack appears to be asbestos/cement pipe, with an outside diameter of about 118mm. My plan is to join the new stack to it with a normal rubber-flanged adaptor (the kind with several rubber "fins" that push into the inside of the pipe). However, not having cut off the old stack at the required joining height yet, and not being too happy about climbing a ladder right to the top of it, I haven't been able to measure its wall thickness, in order to determine its inside diameter. So I can't tell whether the adaptor will seal satisfactorily inside it.

Does anyone know (a) what the inside diameter of the old stack is likely to be, and (b) if it's too big for the modern adaptor, how can I best seal the new to the old, where there is no boss on the old pipe to fill with hemp/cement?

Any and all thoughts and advice would be very welcome, please.

PS: Yes, I know about the precautions I should take when cutting the asbestos/cement pipe.

 

[Flyfisher]

Not really sure of the proper answer but I have a similar task to tackle at some stage with an old lead soil pipe. My thoughts so far have only extended to drilling a small hole in the old pipe in order to determine the inside diameter. This could then be easily filled (e.g. epoxy resin) while sorting out the eventual solution and finding the required adapter.

 

[Penners]

That's a good idea, FF. I was reluctant to drill or cut the pipe until necessary, for obvious reasons! But a modest hole could, as you say, be quickly patched until the full surgical procedure becomes necessary.

Lead soil pipe?! Given today's commodity prices, I should sell it to finance the rest of your project!

 

[Penners]

Update - in case it's of any use to anyone else.

I followed Flyfisher's bright idea, and drilled a hole in the wall of the old stack. I couldn't get the garden hose to the site to wash water over the drilled area (as mentioned above this pipe is asbestos cement), so I coated the pipe with copious quantites of grease to trap the dust - this worked rather well, so long as I stopped regularly to refill the drilled hole with grease.

The outstandingly good news is that the wall thickness of the old pipe is considerable - 8mm, which is much greater than plastic. This means that the internal diameter of the old pipe is only a smidgin-and-a-half greater than the modern pipe. The rubber-flanged connector will therefore work very nicely. Whoopie-dooo!

Thanks again for the excellent idea, FF.

 

[Lime]

Not sure whether the connection is (as the water flows) old to new or new to old.
Also I'm not clear as to what you mean "the kind with several rubber fins that push into the inside of the pipe" because those fittings normally fit into a modern pipe (internal diam. 4" ) and usually connect pipes that are substantially smaller in diameter, i.e. wc bowl spigots or smaller not 110mm pipe or larger.

I suggest something like the flexible adaptor clay to pvc (bottom of link page.

http://www.toolstation.com/shop/Structural/Black+Soil+Vent/d210/sd2849

 

[Penners]

Thanks for your thoughts, Lime.

The new is being connected into the old - that is, the water will flow into the new pipe, then into the old.

The adaptor that I described is identical to the one at the very bottom of your link page (Drain Connector 110mm). A standard 110mm pipe pushes into the end facing the camera, then the finned end is pushed inside a 110mm pipe. Fortunately, as I said above, I now find that this item will work with the old pipe, because its inside diameter is almost identical to that of a modern 110mm pipe - the flexibility of the fins is more than enough the accommodate the tiny difference.

I suppose that my use of the word "pipe" is actually inaccurate, since the nominal dimension (110mm) is actually the outside diameter. Technically, that makes it "tube" rather than "pipe", doesn't it?

Pedantry rules, OK?

 

[Flyfisher]

Glad to hear it worked out well - both the idea and the measured result. Good idea about the grease as well.

As for my lead soil pipe, I was rather surprised to discover it was lead as it wasn't obvious from the many coats of black paint, but it made a very 'dull thud' when tapped with a hammer (er, I mean, my materials analysis toolkit) and a scratch with a screwdriver (the other component of the analysis toolkit) confirmed it as being lead. I dread to think what it would cost these days, assuming it's even available.

Tube-vs-pipe; I knew the distinction is based on measurement but can never remember which is which - so I checked and you're right (of course!).

 

[Penners]

Yup. Proper plumbers Who Know About These Things always refer to copper tube, rather than pipe.

 

[DaveBrigg]

Pedantry! You can put that in your tube and smoke it.

 

[robgil]

pipe has a thicker wall than tube. :wink:

 

[MdB]

The internet is connected together by pipes. It is only silly Americans that think it uses tubes: http://en.wikipedia.org/wiki/Series_of_tubes

 

[DaveBrigg]

pipe has a thicker wall than tube. :wink:

That's worrying. I shan't be taking the London underground again.