MDPE fittings, the good the bad and the ugly

[Chris Green]

I've been doing a little bit of MDPE plumbing just recently and it's not going well.

Previously I've not had big problems with getting watertight and long term reliable connections. I have quite a lot of MDPE buried across our fields feeding two horse waterers and a couple of taps for greenhouses etc. All fairly straightforward and reliable.

Now I am trying to tee off an existing feed (quite recently installed by a builder) to an outside tap to provide a feed for our chcickens. We only have 9 chickens but daily checking the water is a chore. We moved them recently and they used to have an automatic waterer and we want it back!

So I've added a tee to the existing blue pipe, run a pipe across a path, put a stop tap in and then it runs to the chickens.

One tee, two elbows and an in-line tap, simple - no.

Various problems:-

I bought some floplast inserts from Screwfix, they are too tight in the MDPE I have, you can't push them in by hand and so when they need to go somewhere a bit inaccessible they are a complete pain. The older (white rather than black) inserts I have go in much more easily. I've ordered some more, not Floplast, inserts

The in-line tap I have is almost impossible to install on pipes with Floplast inserts (at least I think this is the problem). The plastic rings that push against the sealing rings expand such that the retaining nuts can't be screwed onto the body of the tap. A bit more thread on the tap body would make things much easier.

Pushing the MDPE pipe into the standard O-ring sealed fittings seems more difficult than it should be, I've not found it so difficult before, am I getting feebler (probably) or is there something I can do to make it easier?

I guess it's mostly down to less accessibility than I've had on previous occasions, slightly too big Floplast inserts and a mixture of brands of fittings.

Any advice or comiserations would be very welcome! :-)

[Andy Burns]

In the last 18 months I've used quit a few JG 25mm speedfit fittings

(1xTee, 3xTap connector, 2xStop taps, 2xStraight connector, a bag of inserts) they're not cheap especially the valves, but no problems ...

[Roger Hayter]

Did you use silicone spray, and chamfer the tube ends a bit?

[Chris Green]

Roger Hayter [e-mail] wrote: [snip]

I've started using silicone spray as I had a can on the shelf, it does seem to help a bit but I've not had to use it before. I've not been chamfering either, it shouldn't be necessary should it really? I'm using a 'knife type' pipe cutter so the ends are very clean with no burrs.

[R D S]

Many moons ago, visiting an ex girlfriend's parents, her dad was trying to get mains water to his greenhouses, he'd worked out where the supply to a row of terraces was and dug down to get at the pipe.

The plan was to turn the water off for as brief a time as possible*, cut the pipe, tee off, back on.

*Given that for obvious reasons this was being done in a clandestine manner and on a strict need to know basis.

I can't remember exactly the make up of the fittings but there was a screw on locking collar that needed to go over the pipe *first* before a ring and an insert but in the necessary haste he'd omitted this, realised his error and couldn't get the other bits off/out of the pipe to rectify.

Hilarity ensued while half the village probably wondered why they were without water, me face down in the hole at arms length with a kettle of hot water and a variety of whacking and prising implements.

[John Rumm]

Not really that relevant, but I have found the floplast fittings for

15mm pipe are also a bit on the tight side for my liking - taking quite significant force to get the pipe inserted to the right depth.

ISTR the last time I did MDPE it was fine - but that was defnitely not floplast.

[newshound]

Another +1 for silicone spray on tight plastic joints. One issue with O-rings is that once you damage them you risk having a flow path.