fitting compression joints

[james2006]

Just been plumbing in my new bathroom (used to be the garage) from the main and HW supply. I historically had issues in using compression joints, however I have a number of them weeping through the back of the nut. The only thing I have done differently compared to previous is I deburred the outside of the copper pipe before fitting the joints. I am thinking may have created my imperfections and have caused tiny spaces between the pipe and olive. Any thoughts?

In terms of fixing this issue - do you think using plumbers mait in addition to PTFE tape will do the job?

 

[flameport]

If the pipe is scratched or damaged, then the joint will never seal properly.
Tape or other sealants might help, or they might not. Either way, the real answer is not to make joints onto damaged pipes.

I deburred the outside of the copper pipe before fitting the joints.?

What exactly do you mean by that, and why was it necessary?

 

[ChrisOxford]

Make sure the outside of the pipe is clean and smooth - a rub with a new non-stick pan scourer helps. Reject pipes that have deep gouges or scores, and note that putting a compression fitting very near a bend is sometimes risky as the pipe will often be found to be more oval than round in cross section.

A few people use no compound or tape. I tend to use ONE turn of PTFE tape over the olive once it's on the pipe, OR a smear of Fernox LS-X silicone seaant. Never both.

And don't overtighten. Err on the loose side then "nip-up" the nuts just enough to stop any oozing.

Good luck.

 

[james2006]

after I cut the pipes to the correct length my mate said to use a deburring tool to clean the outside and inside of pipe. This tool made a series of fine scratches on the oustide of the the pipe (it was some sort of hard wire wool).

Normally with a compression joint would you do anythig to the pipe after cutting?

 

[Burnerman]

I'm sure this has been covered a few times before, James but perhaps you are being a little too hard on yourself......
If the copper pipe is new, clean and perfectly round there won't (theoretically) be any need for sealant or tape - however its best to ensure that the pipe is pushed fully into the fitting, and a copper olive is easier to crush down than the brass ones if access is tight.
However as you've already done some of your joints, feel free to add a proprietary sealant and a twist of ptfe tape if you wish. Twist the tape over the olive in the direction that the nut turns, of course, to prevent it unravelling. Dont ptfe over the threads of the fitting.
Old pipe (complete with olive, usually), will always benefit from tape and sealant if used inside another fitting.
John

 

[flameport]

This tool made a series of fine scratches on the oustide of the the pipe (it was some sort of hard wire wool).

Was it like this dreadful item:



The scratches will be the cause of the leaks.

If the pipe is not clean, then extra fine steel wool can be used to clean it.
The cut end should never be rough or burred anyway - if it is, you are using the wrong tool to cut it.

 

[james2006]

so the PTFE tape goes over the olive? I thought you wrapped it around the thread?

 

[james2006]

That was the exact tool! So you think this could be my problem then?

 

[Burnerman]

No mate the seal comes from the olive gripping the pipe, and the taper of the olive mating with the taper of the compression fitting. This is where the tape or sealant goes, not on the threads.
One of the main aquired skills is how tight to wind up the compression nuts, and steady firm pressure from a couple of 6" adjustable spanners is enough. If you overdo it, the olive will crush and the pipe distorts - but naturally if things aren't tight enough then the job leaks, or even the pipe shoots out of the fitting! (I'm talking about 15mm stuff here - bigger sizes need a bit more tightening.
John

 

[flameport]

That was the exact tool! So you think this could be my problem then?

Very likely.
Next time, get one of these or some similar equivalent to cut the pipe with:
http://www.toolstation.com/shop/d10/sd210/p34116

 

[Charnwood]

get one of these or some similar equivalent to cut the pipe with

Yup! Never cut pipe with a hacksaw. The clue is in the name.

 

[gazfen]

[/quote]Yup! Never cut pipe with a hacksaw. The clue is in the name.[/quote]


Ha Ha Fooking Hell

 

[ChrisOxford]

so the PTFE tape goes over the olive? I thought you wrapped it around the thread?

With compression fittings, the tape goes round the olive. And you need literally one turn, so a mere 2" or so should suffice.

For threaded fittings with no olive, e.g. radiator tails, garden "bib" taps and so on, it goes around the threads, in a clockwise direction so that it doesn't unwind as you screw the fitting in.

That scratchy tool of yours is great for prepping when making a soldered joint, but too harsh for compression work, I feel.

As the others have said, using a pipe cutting tool like a Pipeslice is quick and easy, and give a really neat finish that needs no de-burring. Only a tenner or so.