Reusing a compression joint..?

[The Natural Philosopher]

I have just put in some plumbing, one part of which is a compression joint to 22mm pipe, that screws straight into a 3/4" brass fitting.

This screw in joint is weeping very very slightly.

The easy way out is to unscrew the compression joint, and then re-do the screw in bit with more PTFE tape..and then re-screw the compression joint..

I never like re-screwing up a compression joint though, although this one is not totally rammed home.

To remake the pipe that goes into the compression joint is flipping awkward, so I am inclined to take the risk as a shot to nothing really..

What are your experiences of unscrewing a 22mm compression joint and then re-using it without a new olive??

[Homer2911]

Personally, I would re-use it, but using a bit of Plumber's Mait compound

[The Natural Philosopher]

I just did, just more tape on the screw joint, and re-tightened the compression.it had a little bit left..so far...so good.

Gulp.

I hate leaks..

ALL the solder joints I worried about were fine. Just one lousy packed thread.

[Nigel Molesworth]

PTFE tape is not for compression joints. Use Boss White.

[Christian McArdle]

I've done it loads of times. It certainly wouldn't even occur to me to even change the olive, let alone the entire fitting. I never use any jointing compound or PTFE on compression joints.

Christian.

[Ian Stirling]

One problem with this is you don't know how many times this has been done. The olive will work harden sooner or later, and stop working so well.

[The Natural Philosopher]

No, the PFTE was on the screw in part - not the compression joint. The whole assy was to go between 22mm copper and 3/4 thread..the only thing I could find was a 3/4" screw to 22mm compression fitting.

It was the screw in bit that was weeping.

[The Natural Philosopher]

Good. Anyway it worked. There is confusion. The PTFE was not on the compression joint - there was a threaded joint as well.

[The Natural Philosopher]

I do. I did it yesterday for the first time.

Yup. I don't like reusing old ones, but this was brand new. Whole new pipework, bugger of a job, and then one screw joint leaked a teeny bit..and it would be buried in the wall.

Anyway it IS buried in the wall now, and I hope I never have to see it again.

There is a huge dichotomy between neat trim bathrooms and accessible plumbing.

My feeling is that as long as it all lasts longer than HER desire for another complete makeover (10-15 years) that's good enough for me..

[Christian McArdle]

You make it sound like it wasn't the perfect fitting for the job!

Christian.

[Chris Bacon]

It's a metal-on-metal joint, which should be watertight. After the initial deformation it should not be necessary to swing on the spanner when doing the joint up. You can't make a watertight joint more watertight.

[PeTe33]

Tape on the thread?

:¬(

The water shouldn't be getting anywhere near the thread. A few winds around the olive/pipe or some other form of flexible sealant would have been a better solution.

[The Natural Philosopher]

On the other half of the joint.

Screw joint. I had to undo the COMPRESSION joint to remove the screw joint.

Have a look here

code 555031.

And all will become clear..

Again, haven't read what I wrote properly.

[Bookworm]

Wrong. Been using PTFE tape on Compression Joints (where needed) for 30 years. Boss White is not suitable for potable water. Must conform to BS

6920, it doesnt. see

[Chris Bacon]

When is tape or anything else needed for compression joints? The joint is watertight metal on metal.

[Doctor Drivel]

He is right. PTFE should not be used on brass compression joints. There are potable version of jointing paste. This should be used and only a smear between the body of the fitting and the olive.. Do you put PTFE on the threads of a compression joint?

[Doctor Drivel]

In theory you are right. In practice a smear of jointing paste is needed to fill in any imperfections in the olive, fitting and pipe.

[Christian McArdle]

Somewhat unnecessarily, though!

You're right about Boss White, though. Should only be used on heating primary circuits, really.

Christian.

[chris French]

True, but Boss Green is/does.

[robgraham]

Why shouldn't PTFE tape be put on compression joints ? If I've got any concerns about one, I put a couple of wrpas round the nose of the pipe such that it just covers the olive.

And as for the tosh about work hardening !!! Once the olive has been compressed onto the pipe' it's not going to change in dimension again - the metal to metal seal has been made and the seal thereafter is between the olive and the fitting, which might require some assistance in the form of PTFE or paste.

I've never had any problem with re-suing compression fittings - in fact I'm mean enough that I've recycled various bits of off-cuts that have olives on them and never had a problem.

Rob