Compression fitting tightness on plastic pipe?

Apr 15, 2019 Last reply: 7 years ago 12 Replies

When using compression fittings on copper pipe I've always hand-tightened plus half a turn. I think it was just a rule of thumb taught to me by my Dad. I was wondering, however, how tight I should make a compression fitting to plastic pipe - more/less/same? My intuition is saying it should be the same.



If it makes any difference the pipe in question is 15mm Hep2O barrier pipe and I am connecting to a TRV. Incidentally, I am aware of the importance of using an insert.


IME, its a similar "feel" to compression on copper.

Thanks John, that's good to know. I suppose even though the pipe might be plastic it still has rigidity from a metal insert.

I did read somewhere that a copper olive should be used, as opposed to a harder brass one, so that should help with the feel.

The person who invented the name 'Hep2O' took the end of my finger off in 1953.

Bill

Oh, right!

Did he explain why the name? Or was it not the right time given what happened?! ;-)

Really? I'm no strongman but that'd be a stripped thread no question at the very least. BTDTGTTS

Don?t do it. It?s a stupid idea.

Tim

idea.

I disagree with PTFE on a compression fitting.

It should only be used on tapered thread fittings.

Its unreliable on anything else.

Gas fittings require a special thicker PTFE tape and only one turn.

?They leak if you use the thin stuff.

Only if they are bodgers making poor joints on inadequately cleaned pipes, or over tightening the fittings.

Yup, I have never found a need for it as a general rule...

I have used it on the threads as a lubricant a few times where accesss made getting adequate torque on the back nuts difficult, and possibly once or twice over an olive where there was something preventing a perfect seal, and there was no opportunity to change the fitting.

I find if the pipe and fittings are cleaned well, you should get a good join pretty much every time.

I'm sure that when I started DIY plumbing - late 1960s - there was only the thicker PTFE tape.

It?s Jim. Doubling up on spouting bollocks.

Tim

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