Compression fitting on plastic pipe

[Olf]

Zone valve came with compression fittings (olive + nut) on both ends. Speedfit pipe fits just about, but despite tightening the nut I can still turn it and with enough turning I can pull it out (and when filling the circuit under pressure it started moving out as by magic). The olive does not seem to compress and bite the pipe. I'm puzzled as the nut is as tight as I can reasonably make, is there any trick with plastic pipes, should I use copper instead?

On the photo the olive is where it slides up to (there is slight discoloration on the surface of the pipe, but no round witness mark I'd hope for)

 

[Conor]

Are you sure it's not meant to be 16mm pipe rather than 15mm? I.e like you'd have with an UFH manifold.

 

I've used compression fittings on 15mm speedfit pipe loads of times and the olive really digs in (exactly why it's not suitable for compression applications).

Edited October 15, 2022 by Conor

[Radian]

That looks like a hard brass olive. I prefer copper when mating speedfit to metal fittings - which is what used to connect up my single zone UFH.

[Olf]

58 minutes ago, Conor said:

16mm pipe rather than 15mm

This one is 28mm

 

35 minutes ago, Radian said:

That looks like a hard brass olive

Oh, that may be the culprit.

It looks like a trip to try other olives and joining compound in the morning.

[Radian]

16 minutes ago, Olf said:

joining compound

Wouldn't bother. But feel free to wrap PTFE tape OVER the olive and just past it.

[Nickfromwales]

Why not just do this properly?????

Plastic is NOT meant to have a metal olive chew into it, and I’ve said this a number of times here.

Put the zone valve on to a short piece of copper, so the compression setup is 100% concrete solid, and then simply use a pushfit coupler or elbow to convert from copper to pushfit. 

Bombproof.

 

Compression and plastic should not appear in the same sentence, EVER. 👎

[Olf]

7 hours ago, Nickfromwales said:

Why not just do this properly?????

A question I could ask a 'competent professional' work I'm trying to mimic (though I admit it does not leak, unlike my amateurish attempt)

 

Copper it is then, but that prompts for another silly question: the cutter leaves a little of burr inside. What would happen if I left it (I promise not to!)- only effect on the flow, or risk of debris collecting/being released as it wears?

 

[Nickfromwales]

1 hour ago, Olf said:

A question I could ask a 'competent professional' work I'm trying to mimic (though I admit it does not leak, unlike my amateurish attempt)

 

Copper it is then, but that prompts for another silly question: the cutter leaves a little of burr inside. What would happen if I left it (I promise not to!)- only effect on the flow, or risk of debris collecting/being released as it wears?

 

The actual number of clean cut ends I’ve de-burred in my career is close to zilch. Detrimental effects to date? Zilch. Invite a dozen plumbers in to your home and allow each of them to install a section of copper, and see what they do………..

As long as your pipe slice ( rotary cutting tool ) has a nice sharp blade you’ll be fine.

 

 

 

 

 

 

I do, of course, expect you to ignore absolutely all of the above and meticulously de-burr each and every copper section you install, and I will salute you for doing so . 

[Pocster]

9 hours ago, Nickfromwales said:

Compression and plastic should not appear in the same sentence, EVER. 

I’ve had a few fitting like this where the supplier even suggests doing this . I tried it once and with enough force could pull the fitting apart . So when the destructions state olive compression fitting onto Hep2o pipe - I just purchase a threaded hep20 fitting otherwise I won’t sleep at night .

[Olf]

9 hours ago, Nickfromwales said:

meticulously de-burr each and every copper section you install

The cutter came with built-in deburrer, spent whole day spinning it, only now read the comment 😁

 

[Radian]

It's not a waste of time deburring pipe cuts if it prevents Erosion corrosion  

 

 

 

[Nickfromwales]

I know of many heavy smokers who lived into their 80’s and beyond.

Extreme cases can be demonstrated all day long, but the actual flow / velocity etc required, constantly, to create these issues simply do not present themselves in the high majority of domestic installations.

[Radian]

9 hours ago, Nickfromwales said:

I know of many heavy smokers who lived into their 80’s and beyond.

Extreme cases can be demonstrated all day long, but the actual flow / velocity etc required, constantly, to create these issues simply do not present themselves in the high majority of domestic installations.

 

But why risk it if you're not on the clock? Yes, it's an additional step to save if you're doing it every day as a plumber but BH forum users are typically self-builders so can afford to take a little extra care. Cavitation is a real issue, not an imaginary one. In my time I've seen it cause problems in car cooling pumps, ship propellers and my own heating system first hand. Oddly, I'd expect it to be most critical near a circulating pump but I had a pin hole leak from a bit of pipe off a T that looked very much like the above photo on the inside -  and it was in concrete ground floor just about as far away as it could have been. Not worth the risk IMO.

[Nickfromwales]

Indeed. 
Hence;

 

23 hours ago, Nickfromwales said:

 

I do, of course, expect you to ignore absolutely all of the above and meticulously de-burr each and every copper section you install, and I will salute you for doing so . 

 

[Onoff]

As if to prove a point...

 

Nephew had a length of 15mm pkastic pipe inside his house. On the mains. Capped off with a compression isolation valve. Meant for a future outside tap. 

 

It blew off in the week. Even the insert came out!

[dpmiller]

50 minutes ago, Onoff said:

As if to prove a point...

 

Nephew had a length of 15mm pkastic pipe inside his house. On the mains. Capped off with a compression isolation valve. Meant for a future outside tap. 

 

It blew off in the week. Even the insert came out!

what was the failure mode tho- was it undertightened and the olive uncompressed, or overtightened and the olive ate through the pipe?

[Onoff]

23 minutes ago, dpmiller said:

what was the failure mode tho

 

My nephew most likely...