Plastic Pipe

Jul 21, 2011 7 Replies

I am trying to join an old black plastic pipe 18mm od x 12mm id to a modern 15mm plastic pipe. The old black pipe is in an outhouse and I suspect is 50's / 60's era. Have been to my local plumber's merchant to be met with blank looks and the sucking of teeth. Can anyone help with this size conversion. Prefer brass with olives but anything to couple this would be fine.


When I had this problem I found that standard compression fitting for 3/4 copper worked once I found a sleeve in the "Man drawer" that fitted snugly inside.

Mike

plastic can have its diameter changed with a tapered cone and a heat gun.

If you can get both ends to take the ferrules that are used on plastic pipe fittings, it may be possible to use standard plastic couplings.

Another possibility is to stretch both to take a bit of 15mm copper pipe and use jubilee clips, if the pipe is soft and not brittle.

UNIVERSAL TRANSITION FITTINGS are what you want:

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assuming you meant "15mm MDPE" when you said "modern".

I've used one going onto black 1/2" alkathene pipe and it worked very well.

HTH

Tim

Plus you can use the reducing sets on the rest of that page to adapt the

25mm end:

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it turns out the o/d is actually 19mm then it's a job for a 22mm brass compression fitting with a 3/4" olive one end and a 15mm (copper) reducing set in the other.

I don't think it is: the 3/4" referred to the pipe's bore, not its OD. A 3/4" olive would rattle on a 19mm OD pipe, albeit not quite as badly as a 22mm one.

I think Tim is on the right lines here (but I would, wouldn't I, since, iirc, I pointed out these fittings many moons ago)

Quite rite, I spake bollocks in haste.

They are good but bulky, I have used them to transition into lead.

I have a table somewhere that maps all the historical i/d and o/d sizes of copper, plastic, iron and lead, and it has helped with previous queries on this subject in the past but damned if I can find it, I will try again later.

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember Fyne1 saying something like:

If it's low pressure, just heat the pipe and jam a short length of 15mm copper into it, secure with hose clamps on the outside - couple onto that. A solution beloved by farmers for decades.

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