Cannot get compression fitting to seal

grumpycrab

Hello. Inserting  a hard plastic pipe with olive and nut (15mm) but I cannot get a leak free seal. I cannot work out whether the olive is too loose on the hard plastic pipe or whether there's not enough thread on the pipe I'm fitting it too.  Pic is the pipe I'm fitting it too - perhaps there's not enough thread?
Any clues as to what I'm doing wrong?

Browntoa

It's hard to see from that picture

Is the whole thread at the back clear of the tiles ? Is it putting pressure on the back of the plastic pipe? 

Have you tried pfte tape on the thread 

chris_n

Are you using the original nut from that fitting? A non original may be too long and not clamp the olive correctly. Is the plastic pipe meant to have an insert? If so is it there?
Ptfe tape on the threads is not going to fix it, the seal should be between the olive and the fitting and the olive and the nut. Any liquid that gets to the threads has already passed the seal.

benson1980

Put some fernox lsx around the olive and then tighten back up. 

grumbler

Browntoa said:

Have you tried pfte tape on the thread

PTFE tape on thread of compression fittings makes no sense.

grumpycrab said:

Hello. Inserting  a hard plastic pipe with olive and nut (15mm) but I cannot get a leak free seal. I cannot work out whether the olive is too loose on the hard plastic pipe or whether there's not enough thread on the pipe I'm fitting it too.  Pic is the pipe I'm fitting it too - perhaps there's not enough thread?

Your picture is meaningless. It's just thread - the same on all fittings.

In fact, plastic pipes aren't as hard as you think. That's why hard pipe inserts have to be used for any fittings and especially for compression ones. Does your pipe have an insert inside?

shiraz99

What's the olive made from, brass or copper? It's usually recommended to use copper olives with plastic pipes as they are softer and can seal better with plastic, I've always had better success with copper. You could also try some ptfe on the olive itself but that's a bit of a rookie move.

shiraz99

Browntoa said:

It's hard to see from that picture

Is the whole thread at the back clear of the tiles ? Is it putting pressure on the back of the plastic pipe? 

Have you tried pfte tape on the thread 

As mentioned, you don't put ptfe on the thread, if anything you put it on the olive.

Bendy_House

grumpycrab said:

Hello. Inserting  a hard plastic pipe with olive and nut (15mm) but I cannot get a leak free seal. I cannot work out whether the olive is too loose on the hard plastic pipe or whether there's not enough thread on the pipe I'm fitting it too.  Pic is the pipe I'm fitting it too - perhaps there's not enough thread?
Any clues as to what I'm doing wrong?

If you fit just the olive and nut on to that fitting and tighten it down by hand, you should be able to tell when the nut has made contact with the olive - you won't be able to move or turn the olive with yer finger through the open end. Note how far the leading edge of the nut has travelled down the fitting.

Repeat with the olive removed - how much further - if any - does the nut now go down?

That should be able to discount one possible issue here.

What 'hard plastic pipe' are you using? Which brand? Silly Q, but it is 15mm like that fitting (assuming that IS 15mm, of course!)?

When you fit the pipe (with insert) and olive into that fitting, and tighten down the nut, does it start to bite and prevent the pipe from rotating at the expected point? And how much further do you tighten the nut - around a half to one turn, ish? And when you then undo the fitting again, is the olive nicely bedded into the pipe surface and hard to remove?

Silly Q - check the surface of the pipe - are there any score lines on it that could be causing the leak?

shiraz99

Are you trying to fit an electric shower by any chance, is the shower inlet pipe the plastic pipe you're referring to?

Moss5

https://www.screwfix.com/p/jg-speedfit-plastic-push-fit-straight-tap-connectors-15mm-x-2-pack/29175

GDB2222

Moss5 said:

https://www.screwfix.com/p/jg-speedfit-plastic-push-fit-straight-tap-connectors-15mm-x-2-pack/29175

You still need an insert with a push fit connector, just to avoid doubt.