How much PTFE tape on a compression olive

[oldcardriver]

I am fitting a new 3/4 inch "tapered" copper olive to an old but clean 3/4 inch pipe in an old 3/4 inch stop cock, but it keeps seeping a very small amount of water that exits from around the thread, ie I assume it is coming from between the olive and the tap seat and that the seal between the pipe and the olive is good. I have been advised to use PTFE tape, but I wonder how many times I should wrap it round the olive?

Note, I detect the water by wrapping a piece of kitchen towel around the fitting and see a stain a few millimetres long by 1 or 2 mm wide.

Also, I do mean 3/4 inch not 22 mm.

Additionally, the tap is too close to the concrete floor to make replacement difficult and certainly problematical.

 

[45yearsagasman]

2 or 3 wraps should be enough to start with, but on the other hand just use enough to secure the joint.

 

[oldcardriver]

Thanks gasman.
To check for leaks, I fold up half a kitchen towel so that it is about 8 mm wide and then wind it round the joint. I undid the union on the stop cock but was unable to remove the pipe from the stop cock, I had previously done it up very tightly, and was reluctant to apply too much force in case I did any damage to the incoming pipe to the stop cock. The existing 3/4 pipe is very short and I do not have any more 3/4 inch pipe so cannot use a pair of stilsons to hold the pipe as it will obviously damage it. Consequently, I applied 2 layers of PTFE to the top of the exposed olive and overlapped the threads before tightening the union. There is still a similar leak.

EDIT: The next paragraph is rubbish, so ignore it!
I am wondering if this size of leak is worth worrying about? Will the joint eventually seal itself with lime or could the presence of the deposit than just make the situation worse? Or would it be better to keep trying with new PTFE tape?

 

[Agile]

Be aware there cauld always be a small crack in the brass valve body!

Lubricating the nut thread with silicone grease will enable more pressure to be applied to the olive with the same nut torque!

Tony

 

[oldcardriver]

Be aware there cauld always be a small crack in the brass valve body!

Thanks, there maybe now because it creaked the last time that I tightened it

Lubricating the nut thread with silicone grease will enable more pressure to be applied to the olive with the same nut torque!

That is a good idea, but if it does not seal the joint, it will make it more difficult to remove the pipe. Additionally, when I originally tightened the nut, I put an enormous amount of force on the spanner, a number of times.

Access to the tap is hampered because it is directly behind the toilet!!!

Water always appears from beneath the nut, never above it, so I wonder if I put enough PTFE on the thread whether I can seal the thread between the tap and the nut?

 

[kevplumb]

might be better off using paste

 

[oldcardriver]

might be better off using paste

Do you mean use paste to seal the thread between the tap and the nut?

 

[oldcardriver]

Incidentally, the amount of water seeping out appears to be quite small, about 6 hrs ago, 2 am, I wiped the tap dry and tied a thick "Plenty" kitchen towel around the nut. Now the tap is bone dry and the towel is damp but not full of water.

 

[oldbuffer]

Are you absolutely sure its not the gland nut weeping, and the water running down onto the body of the tap? Worth using your dry tissue test around the upper part of the tap to obviate gland nut leakage if possible.

 

[oldcardriver]

Are you absolutely sure its not the gland nut weeping, and the water running down onto the body of the tap? Worth using your dry tissue test around the upper part of the tap to obviate gland nut leakage if possible.

The leak is definitely coming from under the cap nut (I believe that is the correct term) on the outgoing side, ie the top, of the tap.

Edit: added outgoing side etc.

 

[petit_pablo]

Couple of wraps round the olive and refit the valve as normal.