MDPE

[Michael Chare]

I have just bought my first bit of blue MDPE pipe.

What are MDPE pipe inserts sold for?

To cut MDPE pipe would I use my copper pipe cutter or a hack saw?

[Nightjar]

They stop the pipe deforming under a fitting.

You should most definitely NOT use a hacksaw. It needs a clean, smooth, cut end and, for that, you really need a proper MDPE pipe cutting tool.

Colin Bignell

[DerbyBorn]

Nightjar wrote in news:dbudnVpa_uhAepnOnZ2dnUVZ [e-mail]:

Read the instructions and don't compromise!

[John Rumm]

To use with the fittings...

Plastic pipe cutter. e.g:

(you can get cheaper ones for narrower pipe)

[Nightjar]

How disappointing. From the name I expected it to use a laser to cut the pipe.

Colin Bignell

[Roger Mills]

About 20p.

Ah, silly me, that's not what you meant!

They reinforce the end of the pipe where it goes into a fitting, keeping the pipe round (rather than oval) and making the connection more secure.

You're supposed to use a proper plastic pipe cutter. Failing that, a decent pair of by-pass secateurs should do the trick. Cutting - even with the proper tool - inevitably flattens the pipe into a slightly oval shape - so it's important to use an insert.

[fred]

I found my pretty basic speedfit cutter was plenty man enough for 25mm MDPE and it looked as if it would stretch to 35mm too.

This cheapie seems to do up to 42mm too:

[Brian Gaff]

Oh so who invented this stuffand why do we need it? Brian

[Roger Mills]

Dunno who invented it, but it's the blue plastic pipe which you bury in your garden when you want a water supply at the other end.

[The Natural Philosopher]

last half mile water mains...

[John Rumm]

I find a bit of rotation of the pipe to get them started cutting helps reduce the flattening...

[Johny B Good]

[harryagain]

Medium Density Poly Ethylene.

The joints seal with an O ring. (Sometimes other seal depending on make)

The tube needs to be cut square and with no rough edges that might damage the O ring when it is pushed home. There are expensive special tools for cutting it in seconds But you can cut with hacksaw (square) & then take a Stanley knife and shave the saw marks off the edge and make a bevel to ease the pipe into the O ring.

[Nightjar]

On 20/02/2014 07:56, harryagain wrote: ...

Sounds like a recipe for a leak to me, especially as a lot of people cannot make a square cut with a hacksaw.

Colin Bignell

[chris French]

Well, yes obviously you need to take the requisite care making the cut and finishing the pipe end.

It's not the ideal method, but it's perfectly doable, just need take a little time over it.. I did a few joints in a garden supply in MDPE with a saw and stanely knife when I found my plastic pipe cutter was broken and I wanted to get the job done. It was fine.

[Andrew Gabriel]

BTW, hacksaw is fine if you are using compression fittings (which is what I use for long life connections).

You don't want hacksawed ends anywhere near O-ring seals though.

[Rick Hughes]

I'd agree, fine tooth hacksaw and clean edge carefully with a knife .... pipe insert is vital ... I did forget one on my underground rain water harvesting system ... and after 10 years it started to allow air to leak in and the pipe would drain, causing priming issues.