32mm MDPE fittings

[Vijay]

When using 32mm MDPE compression fittings, why do you need a pipe sleeve with some and not others?

 

Cheers

 

Vijay

[Nickfromwales]

15 hours ago, Vijay said:

When using 32mm MDPE compression fittings, why do you need a pipe sleeve with some and not others?

 

Cheers

 

Vijay

Easier if you post links / examples of the fittings so we can comment   

[Vijay]

This one needs a pipe liner https://www.waterirrigation.co.uk/plasson-silverline-straight-compression-coupling-32mm-x-32mm.html  where the likes of these have no mention of needing a pipe liner https://www.toolstation.com/shop/Plumbing/d20/MDPE+Pipe+%26+Fittings/sd2729/MDPE+Straight+Coupling/p59371 or https://www.screwfix.com/p/floplast-493012-mdpe-coupler-32mm-x-32mm/1532f

Edited October 28, 2017 by Vijay

[PeterW]

Most need inserts - the Floplast ones definitely do. 

 

Dont use a catalogue description as the fitting instructions .... 

[Vijay]

I thought the purpose of inserts were  to stop the fitting from crushing the pipe when using olives? Seeing as these rely on rubber O rings to form the seal, do they still compress that much that they would crush the pipe??

[Nickfromwales]

https://www.screwfix.com/p/floplast-mdpe-pipe-inserts-25mm-10-pack/14371

 

 

On this link click more info then q's & a's ?

https://www.screwfix.com/p/floplast-mdpe-pipe-inserts-25mm-10-pack/14371#product_additional_details_container

 

Inserts are required, as said, an item description is just that . 

[Vijay]

It's 32mm I'm using, but is it standard practice to use pipe inserts with all MDPE pipe/fittings then??

[jamiehamy]

I would say so. When you tighten the connection there is a form of clamping occurs I to the pipe which is most likely why the insert is still needed. The rubber ring seals but there is a 'thing' that clamps onto the pipe and bites i. 

[Nickfromwales]

32 minutes ago, jamiehamy said:

I would say so. When you tighten the connection there is a form of clamping occurs I to the pipe which is most likely why the insert is still needed. The rubber ring seals but there is a 'thing' that clamps onto the pipe and bites i. 

+1

[Dyfed]

Hi,

 

i am a plumbing and heating engineer by trade, and on here as I am hoping to do a self build next year!

 

as like all the other comments you deffinetley need to use inserts with all types of fittings! The manufacturer will no warranty any potential failiours if they find that you have fitted them without inserts and you also need to ensure you use an appropriate plastic cutter and not a hacksaw!

[Jeremy Harris]

9 hours ago, Vijay said:

I thought the purpose of inserts were  to stop the fitting from crushing the pipe when using olives? Seeing as these rely on rubber O rings to form the seal, do they still compress that much that they would crush the pipe??

 

The inserts have two functions, and are, as mentioned above, essential.  They do provide a bit of additional stiffening, not for the area where the O ring or lip seal bears, but the bit further up where the grip ring bites into the pipe to hold it in place.  The other reason they are essential is that they provide a smooth entry when pushing the pipe in, because there is a chamfer on the flange part of the insert, preventing the sharp cut edge of the pipe from damaging the O ring or lip seal.

Edited October 28, 2017 by JSHarris

[Bitpipe]

Hmm, I omitted these when building my rainwater tanks - doesn't seem to leaking but I'll retro fit none the less - do I need to scrap the 32mm MPDE pipe I've already used and start again? I've plenty of it so no hardship...

[Jeremy Harris]

1 minute ago, Bitpipe said:

Hmm, I omitted these when building my rainwater tanks - doesn't seem to leaking but I'll retro fit none the less - do I need to scrap the 32mm MPDE pipe I've already used and start again? I've plenty of it so no hardship...

 

The pipe's probably fine, the most likely issue when not using the inserts on low pressure pipe work, where the fitting hasn't been over-tightened, is that the seals can be damaged, as the insert has a smooth chamfer on the flange that covers the cut end of the pipe, to help ease the pipe into either the O ring or lip seal (some MDPE fitting use O rings, some use lip seals).  My experience is that it's quite hard to damage these seals, unless the cut end of the pipe is rough (which is why you shouldn't just hack through it with a saw, but use a proper pipe cutter, which has a very sharp blade).

[PeterW]

Nope the pipe should be fine - slack off and pull the joint apart, put the insert into the pipe and do it all back up. Be aware though that some of the joints won’t come apart easily unless you remove the outer nut and take it completely apart. As you have very little pressure as it’s just the static pressure of 1m of water. . 

[Vijay]

Thank everyone for the explanations, will definitely get inserts then

 

Or are the pushfit fittings any good? https://www.toolstation.com/shop/p96079?table=no

[PeterW]

I may be old fashioned but for stuff buried in the ground I only use decent brands - I use Plasson for all that stuff. 

 

Pipestock do it all at decent prices. 

https://www.pipestock.com/plasson/mechanical-fittings/coupling

 

 

[Vijay]

that's probably a very wise move

 

 

Edited October 29, 2017 by Vijay