Fitting Bib tap - thread preparation
 

Quick one really - When fitting a 1/2" into a wall plate, do I need to put
anything on the thread first (like PTFE), or is this not necessary.

Cheers

Kevin

"Kevin Brady" wrote in message

Quick one really - When fitting a 1/2" into a wall plate, do I need to put
anything on the thread first (like PTFE), or is this not necessary.

Why not use it?

I'd always use PTFE tape personally, costs a few pennies and ensures a leak
free joint.

Dave

David Lang wrote:

Quick one really - When fitting a 1/2" into a wall plate, do I need to put
anything on the thread first (like PTFE), or is this not necessary.


Why not use it?

I'd always use PTFE tape personally, costs a few pennies and ensures a leak
free joint.


It's far better to understand the purpose of PTFE in a joint and use it
accordingly than to just use it on every joint.

In this case, it's a parallel thread joint, which will require some kind
of sealant to make it water tight. PTFE (or alternative) is therefore
required.

However, there are many other types of joint where the seal is created
in a different way (metal/metal, metal/rubber etc.), and using PTFE in
those situations is neither desirable nor recommended.


--
Grunff

On Wed, 03 Aug 2005 09:43:02 +0100, Grunff wrote:

However, there are many other types of joint where the seal is created
in a different way (metal/metal, metal/rubber etc.), and using PTFE in
those situations is neither desirable nor recommended.

I guess most people wouldn't use it on soldered joints. :-)

Are you saying that it is not appropriate for compression joints?

Mr F.

Mr Fizzion wrote:

Are you saying that it is not appropriate for compression joints?

Yes, among others.


--
Grunff

In article , "Grunff"
says...
Mr Fizzion wrote:

Are you saying that it is not appropriate for compression joints?

Yes, among others.

But it can be a good quick bodge on a dodgy compression joint, at
least until you fix it properly.

Rob Morley wrote:

Are you saying that it is not appropriate for compression joints?

Yes, among others.


But it can be a good quick bodge on a dodgy compression joint, at
least until you fix it properly.


I disagree. If a compression joint is leaking, and further tightening
doesn't fix the leak, it is unlikely PTFE will fix it.

Think about how a compression joint is made - the olive is squashed
against the pipe and against the two parts of the fitting. The only
reason for it to leak is if the pipe, olive or fitting is damaged, or it
hasn't been tightened sufficiently.


--
Grunff

In article , "Grunff"
says...
Rob Morley wrote:

Are you saying that it is not appropriate for compression joints?

Yes, among others.


But it can be a good quick bodge on a dodgy compression joint, at
least until you fix it properly.


I disagree. If a compression joint is leaking, and further tightening
doesn't fix the leak, it is unlikely PTFE will fix it.

Think about how a compression joint is made - the olive is squashed
against the pipe and against the two parts of the fitting. The only
reason for it to leak is if the pipe, olive or fitting is damaged, or it
hasn't been tightened sufficiently.

So you wrap tape over the thread and the olive - with luck that will
contain the leak within the fitting.

Rob Morley wrote:

I disagree. If a compression joint is leaking, and further tightening
doesn't fix the leak, it is unlikely PTFE will fix it.

Think about how a compression joint is made - the olive is squashed
against the pipe and against the two parts of the fitting. The only
reason for it to leak is if the pipe, olive or fitting is damaged, or it
hasn't been tightened sufficiently.


So you wrap tape over the thread and the olive - with luck that will
contain the leak within the fitting.


Hmmm...


--
Grunff

In article , "Grunff"
says...
Rob Morley wrote:

I disagree. If a compression joint is leaking, and further tightening
doesn't fix the leak, it is unlikely PTFE will fix it.

Think about how a compression joint is made - the olive is squashed
against the pipe and against the two parts of the fitting. The only
reason for it to leak is if the pipe, olive or fitting is damaged, or it
hasn't been tightened sufficiently.


So you wrap tape over the thread and the olive - with luck that will
contain the leak within the fitting.


Hmmm...


I said it was a bodge :-)

"Mr Fizzion" wrote in message
...
On Wed, 03 Aug 2005 09:43:02 +0100, Grunff wrote:

However, there are many other types of joint where the seal is created
in a different way (metal/metal, metal/rubber etc.), and using PTFE in
those situations is neither desirable nor recommended.

I guess most people wouldn't use it on soldered joints. :-)

Are you saying that it is not appropriate for compression joints?

Mr F.


Yes. I have never used (or needed) any form of sealant in a compression
joint. If the olives don't seal it then there is something wrong, like grit
in it.

Alan.

"Grunff" wrote in message

Are you saying that it is not appropriate for compression joints?

Yes, among others.

I've always used it on compression joints, including high pressure fittings
on CDS hydraulic tube @ 200 bar+ and I've never had a leak yet.

Dave

Thanks for all responses

Ok - PTFE tape on the shopping list for use where a threaded connection
ITSELF is making the seal - i.e. Bib tap as per my original post.

Incidently - the Hep20 website suggests using the tape beneath the olive of
a compression joint to help lubrication , but not to seal the joint.

Regards
--
Kevin B, Oxford
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David Lang wrote:

I've always used it on compression joints, including high pressure fittings
on CDS hydraulic tube @ 200 bar+ and I've never had a leak yet.

But why? It just doesn't make sense - that isn't how the fitting works.


--
Grunff

Kevin Brady wrote:

Incidently - the Hep20 website suggests using the tape beneath the olive of
a compression joint to help lubrication , but not to seal the joint.

Several people have made this suggestion in the past, but I realy don't
like the idea - if you want to lubricate, there are plenty of suitable
products for this which won't in any way interfere with the joint.


--
Grunff

I've always used it on compression joints,

Me too - but I do often wonder if they would have leaked had I not!

"Grunff" wrote in messages

But why? It just doesn't make sense - that isn't how the fitting works

I know, but with mass produced fittings (probably from China) there are
always tolerance issues. PTFE takes up any imperfections in the
thread/olive/tube.

Several people have made this suggestion in the past, but I realy don't
like the idea - if you want to lubricate, there are plenty of suitable
products for this which won't in any way interfere with the joint.

The beauty of tape it that it stays there rather tha being wased away.


Dave

David Lang wrote:
"Grunff" wrote in messages

But why? It just doesn't make sense - that isn't how the fitting works


I know, but with mass produced fittings (probably from China) there are
always tolerance issues. PTFE takes up any imperfections in the
thread/olive/tube.


The olive does a pretty good job of that.

Why would you want to replace a metal/metal seal with a metal/PTFE seal?

I just don't get this "use PTFE regardless" approach - I've made
hundreds of compression joints without PTFE tape on a single one, and
have yet to experience a problem.


--
Grunff

At the risk of a further display of inexperience, doe the PTFE tape around a
bib tap thread fitting 'gunk' it up, meaning that I would not then be able
to unscrew and refix. It's just that this will govern whether I do this part
of the work sooner or later in the list.

Thanks,


--
KEVIN BRADY, Oxford
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Kevin Brady wrote:
At the risk of a further display of inexperience, doe the PTFE tape around a
bib tap thread fitting 'gunk' it up, meaning that I would not then be able
to unscrew and refix. It's just that this will govern whether I do this part
of the work sooner or later in the list.


No, you'll be able to unscrew it with no problems.


--
Grunff

On Wed, 3 Aug 2005 14:26:11 +0000 (UTC), "Kevin Brady"
wrote:

Thanks for all responses

Ok - PTFE tape on the shopping list for use where a threaded connection
ITSELF is making the seal - i.e. Bib tap as per my original post.

Hi,

Might be worth getting a tube of Fernox LS-X or some similar joint
sealer, needs time to set but quicker than faffing with tape ;)

cheers,
Pete.

On Wed, 3 Aug 2005 14:26:11 +0000 (UTC), "Kevin Brady"
wrote:

Thanks for all responses

Ok - PTFE tape on the shopping list for use where a threaded connection
ITSELF is making the seal - i.e. Bib tap as per my original post.

ps...

If using jointing compound put on the thread of the tap so excess is
squeezed out of the joint, not inside.

cheers,
Pete.

In article ,
"Kevin Brady" says...
At the risk of a further display of inexperience, doe the PTFE tape around a
bib tap thread fitting 'gunk' it up, meaning that I would not then be able
to unscrew and refix.

Teflon is actually a rather good lubricant.

"Kevin Brady" wrote in message

At the risk of a further display of inexperience, doe the PTFE tape around
a bib tap thread fitting 'gunk' it up, meaning that I would not then be
able to unscrew and refix.

PTFE tape will make it easier to unscrew.

Loctite on the other hand..........................................!

Dave

"Grunff" wrote in message
...
Rob Morley wrote:

Are you saying that it is not appropriate for compression joints?

Yes, among others.


But it can be a good quick bodge on a dodgy compression joint, at least
until you fix it properly.


I disagree. If a compression joint is leaking, and further tightening
doesn't fix the leak, it is unlikely PTFE will fix it.


Bosswhite jointing compound will. Don't use it too sparingly, though.

Sylvain.

Think about how a compression joint is made - the olive is squashed
against the pipe and against the two parts of the fitting. The only reason
for it to leak is if the pipe, olive or fitting is damaged, or it hasn't
been tightened sufficiently.


--
Grunff

Sylvain Van der Walde wrote:

Bosswhite jointing compound will. Don't use it too sparingly, though.


I'm not going to keep repeating myself, but I'll say it one last time.
There is no need for any PTFE, joining compound, hemp, spit, glue,
silicone or any other crap in a compression joint. Make the joint
properly and it won't leak.


--
Grunff

Grunff wrote:
Sylvain Van der Walde wrote:

Bosswhite jointing compound will. Don't use it too sparingly, though.


I'm not going to keep repeating myself, but I'll say it one last time.
There is no need for any PTFE, joining compound, hemp, spit, glue,
silicone or any other crap in a compression joint. Make the joint
properly and it won't leak.

Yes. Agreed.

But if you *don't* make the joint properly then until you have the
replacement parts/pipe etc. to hand a bit of PTFE will often get you
through...

Thats what 'bodge' means.