When I was a kid, my dad explained how tapered BSP worked (with
hemp/boss white or teflon tape).

But in all my recent wibbings with plumbing, I don't think I have ever
come across a tapered BSP thread.

Where they ever a thing? Seems to be all parallel now and dump shedloads
of teflon on until it feels convincing.

On Fri, 26 Oct 2018 22:45:47 +0100, Tim Watts
wrote:

When I was a kid, my dad explained how tapered BSP worked (with
hemp/boss white or teflon tape).

But in all my recent wibbings with plumbing, I don't think I have ever
come across a tapered BSP thread.

Where they ever a thing? Seems to be all parallel now and dump shedloads
of teflon on until it feels convincing.

Strictly speaking they are BSPT [T aper]


Most fittings do seem to be parallel now and they can be used with
PTFE by building a little "knee" up. This is easer if the build up can
be butted up against a union or similar, but with care a small bumb
can be formed on the male thread. One has to avoid the temptation of
just whacking a few metres of tape around the pipe as it simply gets
displaced as you screw the fittings up.

Oddly enough I saw a colleague use loctite for the purpose this week.
It was certainly a new one for me and it was for high pressure potable
water. Not sure of its WRAS rating, so on the odd occasion when I
still dabble with pipework, I'll stick to PTFE.

AB




---
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On 27/10/2018 00:26, Archibald Tarquin Blenkinsopp wrote:
On Fri, 26 Oct 2018 22:45:47 +0100, Tim Watts
wrote:

When I was a kid, my dad explained how tapered BSP worked (with
hemp/boss white or teflon tape).

But in all my recent wibbings with plumbing, I don't think I have ever
come across a tapered BSP thread.

Where they ever a thing? Seems to be all parallel now and dump shedloads
of teflon on until it feels convincing.

Strictly speaking they are BSPT [T aper]


Most fittings do seem to be parallel now and they can be used with
PTFE by building a little "knee" up. This is easer if the build up can
be butted up against a union or similar, but with care a small bumb
can be formed on the male thread. One has to avoid the temptation of
just whacking a few metres of tape around the pipe as it simply gets
displaced as you screw the fittings up.

Oddly enough I saw a colleague use loctite for the purpose this week.
It was certainly a new one for me and it was for high pressure potable
water. Not sure of its WRAS rating, so on the odd occasion when I
still dabble with pipework, I'll stick to PTFE.

AB

There are certainly specific Loctite products for pipe threads. We used
to use one on instrument fittings on industrial compressors at one
company that I used to work at. That was at 210 Bar.

SteveW

On Friday, 26 October 2018 22:45:52 UTC+1, Tim Watts wrote:
When I was a kid, my dad explained how tapered BSP worked (with
hemp/boss white or teflon tape).

But in all my recent wibbings with plumbing, I don't think I have ever
come across a tapered BSP thread.

Where they ever a thing? Seems to be all parallel now and dump shedloads
of teflon on until it feels convincing.



Tapered threads seal n the thread.
Parallel thread have a washer to seal on the body of whatever it's attached to.

Taper threads are mostly used on steel pipe in large/commercial/industrial heating systems.

https://www.industrialspec.com/about...tandards-intro

On Saturday, 27 October 2018 07:31:16 UTC+1, harry wrote:
On Friday, 26 October 2018 22:45:52 UTC+1, Tim Watts wrote:
When I was a kid, my dad explained how tapered BSP worked (with
hemp/boss white or teflon tape).

But in all my recent wibbings with plumbing, I don't think I have ever
come across a tapered BSP thread.

Where they ever a thing? Seems to be all parallel now and dump shedloads
of teflon on until it feels convincing.



Tapered threads seal n the thread.
Parallel thread have a washer to seal on the body of whatever it's attached to.

Taper threads are mostly used on steel pipe in large/commercial/industrial heating systems.

https://www.industrialspec.com/about...tandards-intro

On Fri, 26 Oct 2018 23:31:14 -0700 (PDT), harry
wrote:

On Friday, 26 October 2018 22:45:52 UTC+1, Tim Watts wrote:
When I was a kid, my dad explained how tapered BSP worked (with
hemp/boss white or teflon tape).

But in all my recent wibbings with plumbing, I don't think I have ever
come across a tapered BSP thread.

Where they ever a thing? Seems to be all parallel now and dump shedloads
of teflon on until it feels convincing.



Tapered threads seal n the thread.

No they dont, they "seal" the thread no more than parallel, probably
less actually. Thread tape or similar seals the thread. No tape and
your taper thread passes as effectively as any other.

IMHO the most advantageous thing about taper was the ease at which
taps, pressure guages and the like could be positioned.

AB

On 27/10/2018 07:31, harry wrote:
On Friday, 26 October 2018 22:45:52 UTC+1, Tim Watts wrote:
When I was a kid, my dad explained how tapered BSP worked (with
hemp/boss white or teflon tape).

But in all my recent wibbings with plumbing, I don't think I have ever
come across a tapered BSP thread.

Where they ever a thing? Seems to be all parallel now and dump shedloads
of teflon on until it feels convincing.



Tapered threads seal n the thread.
Parallel thread have a washer to seal on the body of whatever it's attached to.

Taper threads are mostly used on steel pipe in large/commercial/industrial heating systems.

https://www.industrialspec.com/about...tandards-intro


Also widely used on airline fittings.

--
--

Colin Bignell

On Saturday, 27 October 2018 08:36:16 UTC+1, Archibald Tarquin Blenkinsopp Esq wrote:
On Fri, 26 Oct 2018 23:31:14 -0700 (PDT), harry
wrote:

On Friday, 26 October 2018 22:45:52 UTC+1, Tim Watts wrote:
When I was a kid, my dad explained how tapered BSP worked (with
hemp/boss white or teflon tape).

But in all my recent wibbings with plumbing, I don't think I have ever
come across a tapered BSP thread.

Where they ever a thing? Seems to be all parallel now and dump shedloads
of teflon on until it feels convincing.



Tapered threads seal n the thread.

No they dont, they "seal" the thread no more than parallel, probably
less actually. Thread tape or similar seals the thread. No tape and
your taper thread passes as effectively as any other.

IMHO the most advantageous thing about taper was the ease at which
taps, pressure guages and the like could be positioned.

AB

The tape is a lubricant, Why do you think it's made of PTFE?

On 27/10/2018 08:36, Archibald Tarquin Blenkinsopp Esq wrote:
On Fri, 26 Oct 2018 23:31:14 -0700 (PDT), harry
wrote:

On Friday, 26 October 2018 22:45:52 UTC+1, Tim Watts wrote:
When I was a kid, my dad explained how tapered BSP worked (with
hemp/boss white or teflon tape).

But in all my recent wibbings with plumbing, I don't think I have ever
come across a tapered BSP thread.

Where they ever a thing? Seems to be all parallel now and dump shedloads
of teflon on until it feels convincing.



Tapered threads seal n the thread.

No they dont, they "seal" the thread no more than parallel, probably
less actually.

Yes they do. There is a clearance between parallel threads, and it is
still there when they are done up, just all at one side. But with
tapered threads you compress your hemp/boss white or PTFE up until all
the air has been excluded. And even if you still have a very small
leakage path, it blocks up with solids until it does give a true seal.

Even with a male taper in female parallel and no sealant you can get the
same sort of seal that you get from olives in a compression fitting,
where there is sufficient plastic deformation of the metal to produce a
very good seal indeed. Though (unlike in a compression fitting) there is
a chance of a helical leak path at the tips and roots.

On 27/10/2018 00:32, Steve Walker wrote:
On 27/10/2018 00:26, Archibald Tarquin Blenkinsopp wrote:


Oddly enough I saw a colleague use loctite for the purpose this week.
It was certainly a new one for me and it was for high pressure potable
water. Not sure of its WRAS rating, so on the odd occasion when I
still dabble with pipework, I'll stick to PTFE.

AB

There are certainly specific Loctite products for pipe threads. We used
to use one on instrument fittings on industrial compressors at one
company that I used to work at. That was at 210 Bar.

SteveW

And very good they are too. Screwfix also has two "cheap" versions which
are also fine for domestic temperatures. They have different strengths,
one is intended for permanent joints, the other for ones which you might
have to undo at some time. Very handy if you get asked to look at
connections which have been bodged in the past.

Loctite also do a modern replacement for hemp, it's a very strong fibre
(possibly Kevlar?) about the thickness of thread that you might use on
leather items. This is meant for taper fittings of course.

On Saturday, 27 October 2018 18:03:59 UTC+1, newshound wrote:
On 27/10/2018 00:32, Steve Walker wrote:
On 27/10/2018 00:26, Archibald Tarquin Blenkinsopp wrote:


Oddly enough I saw a colleague use loctite for the purpose this week.
It was certainly a new one for me and it was for high pressure potable
water. Not sure of its WRAS rating, so on the odd occasion when I
still dabble with pipework, I'll stick to PTFE.

AB

There are certainly specific Loctite products for pipe threads. We used
to use one on instrument fittings on industrial compressors at one
company that I used to work at. That was at 210 Bar.

SteveW

And very good they are too. Screwfix also has two "cheap" versions which
are also fine for domestic temperatures. They have different strengths,
one is intended for permanent joints, the other for ones which you might
have to undo at some time. Very handy if you get asked to look at
connections which have been bodged in the past.

Loctite also do a modern replacement for hemp, it's a very strong fibre
(possibly Kevlar?) about the thickness of thread that you might use on
leather items. This is meant for taper fittings of course.

poundland polypropylene rope does that job fine. £1 for what was it, 20 or 30m. Ordinary products marketed for specialised purposes always seem to attract silly prices.


NT

The beauty of hemp is the fibres swell in the presence of moisture so any minor imperfections/drips heal quickly in use