Joining metric to Imperial pipe.

[Anode]

I want to join 15mm copper pipe to another pipe which is Imperial polyethylene, Class C, low density to BS 1972/67, and installed around 1968.

This polyethylene pipe is of nominal size half inch, with an outside diameter of 21.5mm, wall thickness a little under 3mm. It is black in colour, and is to be used overground.

For the connector, will it be all right to use a metal (such as Kuterlite)

22mm to 15mm reducing fitting, with a three-quarter inch imperial copper olive at the 22mm end going over the polyethylene pipe? I have a metal pipe insert available that was left over from when the pipe was originally installed in around 1968.

[John Rumm]

Sounds like it ought to be ok. Failing that BES do transition fittings that will mate with all sorts of pipe including lead. iron, plastic etc., and each one covers quite a range of sizes.

[Anode]

Thanks John for your thoughts. I shall probably go ahead and see what happens, as you think it may well be all right.

I have since discovered that Kuterlite list a fitting, K1710KP that is marked Polyethylene to Copper,1/2 inch x 15mm, which seems to be made for this job, but I have not yet found anyone who sells them singly. And the BES fittings are a bit more bulky than the Kuterlite type and I have got limited space to get the fitting in.

Regards,

Anode.

[Roger Mills]

It sounds like the stuff that supplies water to my house. ISTR that 3/4" compression fittings are ok with it - so a 22mm fitting with a 3/4" olive should be ok.

[Anode]

John and Roger,

What has happened is I have eventually been able to find a local supplier of that K1710KP fitting. It has a brass 15mm olive at the copper-connection end, and a copper olive at the other end for the polyethylene-connection. The nut at the polyethylene end has a finer thread than that at the copper-connection end, and, so says a leaflet, is made of a copper alloy.

So it will make sense to use this specialist fitting now I have got it, though whether the long-term end result will be noticeably different from putting a 3/4inch olive in a standard fitting I do not know.

Thank you for your input.

Regards,

Anode.

[Roger Mills]

Well, you obviously won't go wrong by using the proper thing!

On reflection, I can't be sure that that's not what I've got. It *looked* like a 3/4" compression joint, but it could well have been a K1719KP or equivalent. [It's buried deep under my sink, so I can't easily re-check].