NPS vs.NPT
John Jacobs
to npt. I think I only ever tapped one or two nps holes in eleven years.
Just wondering what they are better suited for. Thanks in advance.
John (lost the damn chuck key again) Jacobs
Jay Hayes
The straight thread allows for maximum adjustibility. NPS threads are also
used for fluids, where a gasket or other seal is used to seal the joint.
The NPT thread is used for fittings, where tightening the tapered connection
creates the seal so the joint won't leak.
Jay Hayes
Weston, WV
Peter
>>
I would like some feedback on the advantages of nps threads as opposed
to npt.
>>
NPS is non-sealing (straight threads, hence "S").
NPT is dry-sealing (tapered threads, hence "T").
If you're making fittings for the electrical industry, you must use NPS
threads.
If you're making threads for the plumbing industry, you must use NPT threads.
At one time (perhaps still) the National Electrical Code (NEC) required that
all electical conduit and fittings be non-intermateable with water and gas pipe
and fittings, hence the requirement for NPS on electrical parts.
mull...@advinc.com
peter...@aol.communicate (Peter) wrote:
> NPT is dry-sealing (tapered threads, hence "T").
Somebody correct me if I'm in error here, but I belive that
true dry-seal threads are a special sub-set of NPT threads.
They have to be machined in a special way to allow them to
seal without any form of thread tape or sealant.
Regular NPT threads have a small amount of space over the
crest of the male thread, and under the root of the female one.
So if an NPT fitting that has been assembled with sealant is
overpressured enough, that tiny bit of sealant will be extruded
out of the fitting in a corkscrew. I have seen pictures of
this in fitting manufacturers books.
Jim
Sent via Deja.com http://www.deja.com/
Before you buy.
Phil Kangas
Mulligan wrote in message :
>
>> NPT is dry-sealing (tapered threads, hence "T").
>
>Somebody correct me if I'm in error here, but I belive that
>true dry-seal threads are a special sub-set of NPT threads.
>They have to be machined in a special way to allow them to
>seal without any form of thread tape or sealant.
I believe you are referring to NPTF (National Pipe Tapered
Fuel).
Also, do not ever use tape on any hydraulic fitting, ever!
Even
one little free strand of tape will drive you nuts till you
find it.
NPS threads are intended for O-ring type hydraulic
connections.
They allow you to orientate the hose in an ideal position.
The
nut on the NPS fitting then compresses the o-ring into a
chamfer
to seal the connection.
Phil Kangas
mull...@advinc.com
"Phil Kangas" <pka...@spam.free.portup.com> wrote:
> Also, do not ever use tape on any hydraulic fitting, ever!
Or on CGA connections to gas bottles - drives me crazy
when folks do that!
Ned Simmons
pka...@spam.free.portup.com says...
>
> Mulligan wrote in message :
> >
> >> NPT is dry-sealing (tapered threads, hence "T").
> >
> >Somebody correct me if I'm in error here, but I belive that
> >true dry-seal threads are a special sub-set of NPT threads.
> >They have to be machined in a special way to allow them to
> >seal without any form of thread tape or sealant.
>
> I believe you are referring to NPTF (National Pipe Tapered
> Fuel).
> one little free strand of tape will drive you nuts till you
> find it.
> NPS threads are intended for O-ring type hydraulic
> connections.
> They allow you to orientate the hose in an ideal position.
> The
> nut on the NPS fitting then compresses the o-ring into a
> chamfer
> to seal the connection.
> Phil Kangas
>
> >
> >Regular NPT threads have a small amount of space over the
> >crest of the male thread, and under the root of the female
> one.
> >So if an NPT fitting that has been assembled with sealant
> is
> >overpressured enough, that tiny bit of sealant will be
> extruded
> >out of the fitting in a corkscrew. I have seen pictures of
> >this in fitting manufacturers books.
> >
> >Jim
>
>
>
>
NPSF is Dryseal Fuel
Then there's NPSI and PTF-SAE NPSM, NPSL.....
Standard O-ring boss hydraulic lines use regular UNF threads; 5/16-24,
3/8-24, 7/16-20, 1/2-20, etc.
Confusing, no?
Ned Simmons
Phil Kangas
Ned Simmons wrote in message ...
>Confusing, no?
>
>Ned Simmons
>
Yeah, it sure can be! Like those darn British Standard
Pipe threads, like 3/8-19 BSP!
Phil
lha...@unm.edu
>In article <mIYj4.1404$e56....@monger.newsread.com>,
> "Phil Kangas" <pka...@spam.free.portup.com> wrote:
>
>
>when folks do that!
>
>Jim
>
Yes, and on gass bottle regulators. Use to find that on a lot
of He, N2, etc bottles in the Chem dept. Done by grad students
that had no clue as what they were doing. Oh Well thats all in the
past, 2 yrs now and havent had to even look at a grad student. :-)
...lew...
Robert Bastow
So who dreamed up elevenanferchristsakesahalf TPI??
teenut
Peter Drumm
<pka...@spam.free.portup.com> writes:
:->
:->
:->Mulligan wrote in message :
:->>
:->>> NPT is dry-sealing (tapered threads, hence "T").
:->>
:->>Somebody correct me if I'm in error here, but I belive that
:->>true dry-seal threads are a special sub-set of NPT threads.
:->>They have to be machined in a special way to allow them to
:->>seal without any form of thread tape or sealant.
:->
:->I believe you are referring to NPTF (National Pipe Tapered
:->Fuel).
:->Also, do not ever use tape on any hydraulic fitting, ever!
That depends on who you listen to or believe. At work the different
manuals all say something different. While one manufacturer will say
'never use PTFE tape on hyd fittings', the next one says 'never use
pipe joint compound on hyd fittings', the third says 'use of PTFE tape
is required on all hyd fittings', yaddayaddayadda...
I use tape on everything and haven't had any problems with it.
Custom machining; Tool & Cutter grinding
Peter Drumm, Wausau WI <pdr...@dwave.net>
<http://home.dwave.net/~pdrumm>
Cyrix6x86/300 MII, OS/2 Warp 4, Linux
Phil Kangas
tpi?
>teenut wrote in message ...
Phil Kangas
Peter Drumm wrote in message ...
>
>I use tape on everything and haven't had any problems with
it.
>
YET!
John Jacobs
" I recently went to France and they had the odasity not to speak
english"
I feel the same for all of those 1/4-19 thread sizes
JJ
Peter Drumm
<pka...@spam.free.portup.com> writes:
:->
:->
:->Peter Drumm wrote in message ...
:->
:->>
:->>I use tape on everything and haven't had any problems with
:->it.
:->>
:->
:->
:->YET!
After 18 years, I'd think 'yet' is irrelevant. However, a 1/4" ball
that gets into the swing valve on a backhoe is relevant, and I've
dealt with those twice now.
rajeevsa...@gmail.com
Your answer is the most convincing.
Thanks....
Rajeev Kumar
Mumbai
INDIA