On Tuesday, 21 February 2017 19:32:23 UTC, newshound wrote:
On 2/21/2017 7:03 PM, tabbypurr wrote:
3 plumbing joints done with ptfe tape all leak. I mostly don't use ptfe to seal joints. 2 of the joints are 15mm compression tee (with one male end, one female end) onto an extension piece, the other is extension piece onto brass threaded ballcock. 1.5 turns of yellow/gas ptfe tape each, all neatly in place. I admit to not being clear how the nut would seal to the tee it's on. The one joint done with fibre washer & gloop works fine of course, but I don't think that approach can be used with the other joints.
I'm clearly making a basic mistake here. Did I mention I don't like plumbing?
NT
When you say compression tee, do you mean the pipe has an olive on it?
Like an ordinary compression fitting (that takes pipe with olive) except that one end is reversed, ie male not female. It thus has a nut on that screws onto another fitting. I've added 2 threaded extension pieces, one on each port, to make the combined fitting long enough to reach both pipe and ballcock.
IIRC fittings to a ballcock are also normally done with an olive.
Neither the current or previous one were/are. The male bit of the compression elbow is screwed onto the ballcock.
You should not be trying to use PTFE tape to seal any significant water
pressure. But IMHO it is worth using tape on compression fittings *to
reduce the friction*, which means you get more axial pressure for a
given torque. Lots of people tell you that you must not put tape *over*
the olive or the cones but a single turn won't matter.
There are basically three ways to seal with threaded connectors.
One is using tapered threads, these are sealed with fibre, traditionally
hemp but now usually Loctite synthetic thread. A smear of "Boss White"
is also needed.
The second is the washing machine or garden tap connector. You need a
soft washer, either rubber or fibre, trapped in the female (hose)
fitting against the end face of the tap. Tap fittings use a variant of
this, with a thinner fibre washer trapped against the tap by a flange on
the male fitting.
The third is the compression fitting, where you are trapping an olive
between cones on the male and female parts. This relies on squeezing the
olive tightly enough on the pipe so that fluid cannot flow between the
olive and the pipe (sometimes a problem with chromed pipes).
There are liquid sealants which can be applied to threaded joints, I
usually think they are a bit of a "bodge" but sometimes you are
constrained by, for example, a damaged cone on a fixed part, or a scored
pipe. I always carry some in my plumbing toolbox.
I'll see if I can get washers in there, but from a quick look I doubt I can.. In which case I could use some sort of fairly quick setting stuff, but that still won't seal the nut to the male end of the compression fitting.
elbow is like this:
https://www.raygrahams.com/images/th...052314_700.jpg
extensions look like this but without the nut on:
https://www.raygrahams.com/images/th...038720_188.jpg
NT