PTFEed Joints weeping

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, o ne female end) onto an extension piece, the other is extension piece onto b rass 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 plumbin g?

NT

Reply to
tabbypurr
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snipped-for-privacy@gmail.com brought next idea :

Compression joints should not need anything else to seal them, the olive is supposed to deform to make the seal between fitting and nut and the pipe. The pipe end should go well into the fitting, to keep things aligned.

Reply to
Harry Bloomfield

the joints in question don't have an olive. They're screw threaded extensions to compression fittings. The tape goes on the screw thread.

And yes, I do use gloop on compressions, old pipe does not seal reliably without.

NT

Reply to
tabbypurr

When you say compression tee, do you mean the pipe has an olive on it? IIRC fittings to a ballcock are also normally done with an olive.

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.

Reply to
newshound

Well basic mistake one to my mind is using PTFE tape with compression joints. PTFE and compression joints don't mix - where did you put the tape anyway?

Reply to
Chris Green

to seal joints. 2 of the joints are 15mm compression tee (with one male en d, one female end) onto an extension piece, the other is extension piece on to brass threaded ballcock. 1.5 turns of yellow/gas ptfe tape each, all nea tly 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.

Like an ordinary compression fitting (that takes pipe with olive) except th at one end is reversed, ie male not female. It thus has a nut on that screw s 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 ball c*ck.

Neither the current or previous one were/are. The male bit of the compressi on elbow is screwed onto the ballcock.

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 th at still won't seal the nut to the male end of the compression fitting.

elbow is like this:

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extensions look like this but without the nut on:
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NT

Reply to
tabbypurr

So where is the seal? Assuming these are parallel threads, you will need a soft washer on the axial face (unless you fill up the thread clearance with some sort of fluid sealant)0

OK then you need another soft washer (fibre or rubber) on the axial face.

That needs a tapered male thread although you might get away with a washer

I would expect there to be an olive between the nut and the fitting

Reply to
newshound

Although this is the conventional wisdom, IMHO it is always worth putting PTFE tape on the threads because it reduces the friction coefficient. So you get more axial force for a given torque. It's the axial force which makes the seal.

Reply to
newshound

fe 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 n eatly in place. I admit to not being clear how the nut would seal to the te e it's on. The one joint done with fibre washer & gloop works fine of cours e, but I don't think that approach can be used with the other joints.

t that one end is reversed, ie male not female. It thus has a nut on that s crews 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.

I thought the ptfe between the screw threads was going to do it, but clearl y not.

yes, hoping I have a suitable washer now.

ession elbow is screwed onto the ballcock.

can. In which case I could use some sort of fairly quick setting stuff, bu t that still won't seal the nut to the male end of the compression fitting.

I'm more than puzzled by the idea of using a tapered thread with it

which nut and which fitting? I can't imagine how one would get an olive bet ween the extension piece and the elbow.

a puzzled NT

Reply to
tabbypurr

It's the squishing of the olive round the pipe that makes the seal surely. OK, some PTFE tape on the thread may help by lubricating it but surely a quick dab of grease or oil would actually work better as a lubricant.

Reply to
Chris Green

Tapered threads are sized so that they become completely tight before the male thread has bottomed in the female component. On its own, a tapered thread can't normally make a gas-tight seal, but the leakage path will be small, so it can be sealed by something like boss white. A down-side of tapered joints is that you don't have much control of the orientation of the parts at the point where they become tight. However by having something like hemp threads wrapped around the male threads, you can influence the point at which it becomes tight, and hence control the angular orientation. Tapered threads are not so commonly used in copper systems, but they were the standard system in "old" iron pipe, e.g. in "gravity" hot water systems, and are sometimes used for hand-rails and guard rails. It's a bit of an art building a complicated "3D" system in iron.

This picture shows two components. A sort of sleeve with a female thread at one end, and a male thread on the other. There is a nut on the male thread. I would expect there to be an olive "inside" the nut. This would let you seal a piece of copper pipe to the right hand end of the fitting, by tightening the nut (with the olive in place).

Reply to
newshound

Wisdom says use a proper lubricant.

Lubricant doesn't creep like PTFE.

PTFE is intended for taper threads.

Whenever I see PTFE tape on a compression fitting you can always tell it's a rank amateur.

In practice you can supply more than enough force to a compression fitting to destroy an olive, such there ought not be any need for lubricant.

Reply to
Fredxxx

That's not always the case - it really depends on location and how easily you can get a spanner on it (not to mention the type of spanner[1]). In some circumstances you can't get adequate torque without lubrication on the threads, and PTFE does the job without getting grease all over the place.

[1] 'Orible stamped steel things like this:

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will get into all kinds of gaps more manly spanners won't, but they can be a bugger to get enough torque on the nut - especially on 22mm and larger fittings.

Reply to
John Rumm

Personally I would not use gas PTFE in this application - its can be too thick.

Some photos of the actual fittings you are using might help to get a clearer understanding.

Generally if its got an olive, and the pipe is clean - then it will normally seal fine without additional stuff. If you are trying to get a seal on a threaded connector. Then you need either a washer or O ring that can seal against the flat on the surface of the fitting (e.g. like on a tap connector), or you need a tapered male fitting + sealing "stuff" to go into it. (ideally tapered fittings should be used in pairs i.e. taper male into taper female - however in reality a taper male will normally seal into a parallel female with lots of PTFE (as commonly done on rad tails))

Reply to
John Rumm

That sounds like you have a male - female nipple. They aren't extension pieces for extending a compression joint. They have tapered threads and the compression fitting will have parallel threads.

You need a short bit of pipe and some proper compression or solder fittings, or do it the easy way and use pushfit.

Reply to
dennis

o 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 neatl y 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, b ut I don't think that approach can be used with the other joints.

Here's the steward of the bar in question

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NT

Reply to
tabbypurr

The problem joints don't involve a pipe or olive. They're where 2 parts are screwed together.

NT

Reply to
tabbypurr

ptfe to seal joints. 2 of the joints are 15mm compression tee (with one mal e end, one female end) onto an extension piece, the other is extension piec e 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 cou rse, but I don't think that approach can be used with the other joints.

ept 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 o n each port, to make the combined fitting long enough to reach both pipe an d ballcock.

pression elbow is screwed onto the ballcock.

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 fittin g.

between the extension piece and the elbow.

that's what the extension pieces are

But that lot doesn't come into it. No nut, no olive, no pipe.

NT

Reply to
tabbypurr

Of all the plumbing spanners my flat stamped one is one of the more useful. It's more than thick enough to get serious torque on the nuts - but it is the thickest stamped one I've ever seen. The slight offset makes it even mo re getinnable. It's designed for car fans.

NT

Reply to
tabbypurr

ok doc.

Not enough room - I could redo the whole area using new fittings, and might have to. Maybe I could attach the 'extensions' whatever they may be with epoxy.

NT

Reply to
tabbypurr

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