Male threading of 15mm compression and 1/2" female
asalcedo
Does the male threading of a 15mm compression fitting (like one side of
a 15mm compression coupler) fit well into a 1/2" female thread?
I have confirmed that it screws in well, but, using PTFE tape, can it be
secure and water tight?
If so, in picture at 'zSHARE - VG5V9782.JPG'
(http://www.zshare.net/image/82011190dab15aa1/), the valve could screw
directly into the 1/2" brass tee.
Thanks,
Antonio
--
asalcedo
F Murtz
have seen in a while.
Andy Burns
> (http://www.zshare.net/image/82011190dab15aa1/), the valve could screw
> directly into the 1/2" brass tee.
That pushfit connector on the end of the isolation valve looks to be
under a bit of strain ... I'd be tempted to support the plastic pipe.
nicknoxx
trying to show you
http://www.zen202900.zen.co.uk/pics/temp.JPG
Onetap
> Does the male threading of a 15mm compression fitting (like one side of
> a 15mm compression coupler) fit well into a 1/2" female thread?
>
> I have confirmed that it screws in well, but, using PTFE tape, can it be
> secure and water tight?
No, it's a parallel 1/2" BSP male thread, screwed into a parallel
female thread. You may get it to seal, but the joint won't tighten as
it is screwed in.
A screwed joint like that should be made with a taper thread. Buy a
1/2" compression to 1/2" male adaptor.
Roger Mills
> A screwed joint like that should be made with a taper thread. Buy a
> 1/2" compression to 1/2" male adaptor.
Or, rather, a 15mm comp to 1/2" male iron.
--
Cheers,
Roger
____________
Please reply to Newsgroup. Whilst email address is valid, it is seldom
checked.
asalcedo
Bravo! Thank you for the helpful answer.
It brings up the key issue here. The difference between taper and
parallel thread seems to explain it all.
However, following on your input, I have now researched the issue of BSP
threads a bit further and, according to
http://en.wikipedia.org/wiki/British_standard_pipe_thread
the 1/2" male thread, the one coming from the valve that has a
compression fitting on one side, is tapered. This is because, according
to the same article, in Europe female tapered threads are not used. And
since the compression fitting is definitively a jointing thread, the
male has to be tapered.
If this is so, the initially proposed joint would be tapered 1/2" male
into a parallel 1/2" female, which should be a fully functioning
jointing thread.
Am I missing something?
P.D.: As you can see in the picture
http://www.zen202900.zen.co.uk/pics/temp.JPG
, I already have a 15mm compression to 1/2" male adaptor. The point is
whether I can get rid of that adaptor and the small 15mm pipe
P.D: Sorry for the z-share hosting. It used to be good.
Onetap;2523131 Wrote:
> On 26 Oct, 21:09, asalcedo asalcedo.70d3...@diybanter.com wrote:-
> Does the male threading of a 15mm compression fitting (like one side
> of
> a 15mm compression coupler) fit well into a 1/2" female thread?
>
> I have confirmed that it screws in well, but, using PTFE tape, can it
> be
> secure and water tight?-
>
> No, it's a parallel 1/2" BSP male thread, screwed into a parallel
> female thread. You may get it to seal, but the joint won't tighten as
> it is screwed in.
> A screwed joint like that should be made with a taper thread. Buy a
> 1/2" compression to 1/2" male adaptor.
--
asalcedo
Roger Mills
> Bravo! Thank you for the helpful answer.
>
> It brings up the key issue here. The difference between taper and
> parallel thread seems to explain it all.
>
> However, following on your input, I have now researched the issue of BSP
> threads a bit further and, according to
> http://en.wikipedia.org/wiki/British_standard_pipe_thread
>
> the 1/2" male thread, the one coming from the valve that has a
> compression fitting on one side, is tapered. This is because, according
> to the same article, in Europe female tapered threads are not used. And
> since the compression fitting is definitively a jointing thread, the
> male has to be tapered.
>
> If this is so, the initially proposed joint would be tapered 1/2" male
> into a parallel 1/2" female, which should be a fully functioning
> jointing thread.
>
> Am I missing something?
>
I'm afraid that you *are* missing something. A compression joint does
*not* seal on the threads - it seals by crimping an olive onto the pipe
and by squeezing the edges of the olive between conical faces on the
fitting and nut. The thread is *parallel*!
When you screw a parallel-threaded male fitting into a parallel female,
the seal is normally made between two faces by using a fibre washer or
somesuch - and *not* on the threads. With the fittings in your photo,
there isn't a face in sight!
OK, all of that is the official party line - the purist view, if you
like. In reality, you could probably do what you want to do - and screw
the valve directly into the tee. If you screw it in as far as it will
go, *something* will stop it going any further. This may be the end of
the valve bottoming in the tee, or it may be that you've run out of
thread on the valve. Either way, there will be metal to metal contact
which - assisted by copious amounts of liquid PTFE, will almost
certainly provide an adequate seal.
asalcedo
Hello Roger, thank you again for the helpful answer, which I agree with
fully and settles the issue.
One related question, when one screws a brass threaded male into a brass
threaded female (like the brass adaptor into the brass tee in the
picture), I assume that the male thread is tapered. Is this correct?
And a follow up question. Is PTFE tape (or similar) always required when
screwing a tapered thread into a parallel one? Isn't (theoretically at
least) the taper enough to provide a metal against metal functioning
joint?
I mention this because I know that in compression joints there is no
need to use jointing compound or PTFE tape, the deformation of the olive
provides the seal.
Is it because the brass threads are too hard to have enough deformation
to provide a good seal?
Could it be that by not having to permanently deform the thread, by
using the PTFE tape, one can always undo the joint?
'Roger Mills[_2_ Wrote:
> ;2523487']On 27/10/2010 18:15, asalcedo wrote:-
> Bravo! Thank you for the helpful answer.
>
> It brings up the key issue here. The difference between taper and
> parallel thread seems to explain it all.
>
> However, following on your input, I have now researched the issue of
> BSP
> threads a bit further and, according to
> 'British standard pipe thread - Wikipedia, the free encyclopedia'
> (http://en.wikipedia.org/wiki/British_standard_pipe_thread)
>
> the 1/2" male thread, the one coming from the valve that has a
> compression fitting on one side, is tapered. This is because,
> according
> to the same article, in Europe female tapered threads are not used.
> And
> since the compression fitting is definitively a jointing thread, the
> male has to be tapered.
>
> If this is so, the initially proposed joint would be tapered 1/2" male
> into a parallel 1/2" female, which should be a fully functioning
> jointing thread.
>
> Am I missing something?
> -
>
> I'm afraid that you *are* missing something. A compression joint does
> *not* seal on the threads - it seals by crimping an olive onto the pipe
>
> and by squeezing the edges of the olive between conical faces on the
> fitting and nut. The thread is *parallel*!
>
> When you screw a parallel-threaded male fitting into a parallel female,
>
> the seal is normally made between two faces by using a fibre washer or
> somesuch - and *not* on the threads. With the fittings in your photo,
> there isn't a face in sight!
>
> OK, all of that is the official party line - the purist view, if you
> like. In reality, you could probably do what you want to do - and screw
>
> the valve directly into the tee. If you screw it in as far as it will
> go, *something* will stop it going any further. This may be the end of
> the valve bottoming in the tee, or it may be that you've run out of
> thread on the valve. Either way, there will be metal to metal contact
> which - assisted by copious amounts of liquid PTFE, will almost
> certainly provide an adequate seal.
> --
> Cheers,
> Roger
> ____________
> Please reply to Newsgroup. Whilst email address is valid, it is seldom
> checked.
--
asalcedo
Roger Mills
> Hello Roger, thank you again for the helpful answer, which I agree with
> fully and settles the issue.
>
> One related question, when one screws a brass threaded male into a brass
> threaded female (like the brass adaptor into the brass tee in the
> picture), I assume that the male thread is tapered. Is this correct?
>
Usually, yes.
> And a follow up question. Is PTFE tape (or similar) always required when
> screwing a tapered thread into a parallel one? Isn't (theoretically at
> least) the taper enough to provide a metal against metal functioning
> joint?
>
Don't forget that the thread is a spiral - not a ring - so water can
work its way round the spiral between the two components. PTFE tape
fills up the gaps, and prevents this from happening.
> I mention this because I know that in compression joints there is no
> need to use jointing compound or PTFE tape, the deformation of the olive
> provides the seal.
>
> Is it because the brass threads are too hard to have enough deformation
> to provide a good seal?
>
No. It's because of the spiral. An olive, on the other hand, provides a
complete continuous metal to metal ring at each end, so there are no
gaps for the water to get through.
asalcedo
Thank you again Roger for sharing your knowledge.
Antonio
'Roger Mills[_2_ Wrote:
> ;2523999']On 28/10/2010 11:50, asalcedo wrote:-
> Hello Roger, thank you again for the helpful answer, which I agree
> with
> fully and settles the issue.
>
> One related question, when one screws a brass threaded male into a
> brass
> threaded female (like the brass adaptor into the brass tee in the
> picture), I assume that the male thread is tapered. Is this correct?
> -
>
> Usually, yes.
>
> -
> And a follow up question. Is PTFE tape (or similar) always required
> when
> screwing a tapered thread into a parallel one? Isn't (theoretically at
> least) the taper enough to provide a metal against metal functioning
> joint?
> -
>
> Don't forget that the thread is a spiral - not a ring - so water can
> work its way round the spiral between the two components. PTFE tape
> fills up the gaps, and prevents this from happening.
>
> -
> I mention this because I know that in compression joints there is no
> need to use jointing compound or PTFE tape, the deformation of the
> olive
> provides the seal.
>
> Is it because the brass threads are too hard to have enough
> deformation
> to provide a good seal?
> -
> No. It's because of the spiral. An olive, on the other hand, provides a
>
> complete continuous metal to metal ring at each end, so there are no
> gaps for the water to get through.
>
>
> --
> Cheers,
> Roger
> ____________
> Please reply to Newsgroup. Whilst email address is valid, it is seldom
> checked.
--
asalcedo