On May 13, 12:51*pm, Oren wrote:
On Mon, 13 May 2013 10:51:04 -0700 (PDT), "

wrote:
" professional installers" ??? yeah, right!
from the layout, they look like hacks

+++++1

I wager a hazard, that the pool cost around 200G new.

Depends on when it was built but with that hidden cover storage &
automatic cover.... 200k ain't far off.

On May 13, 6:09*am, "
wrote:
On May 12, 8:01*pm, Vic Smith wrote:

On Sun, 12 May 2013 17:18:09 +0000 (UTC), Danny D
wrote:

The only proscription against that stuff, based on
the Vic Smith article, was the fact it also lubricates
as it seals.

Please quit saying that's "my article." *I didn't write that, I just
cited it.

I think we all understood that's what he meant.

*I have no experience at all with threaded plastic pipe.

And I'm not buying all this emphasis on "lubricate vs non-lubricate."
As long as it's compatible with the plastic, seals the threads, and
doesn't harden up, it should work.

I agree. *For that matter, Teflon tape is widely used and if it
made a huge difference, there would be leaking fittings everywhere.
Yet, lots of people, including many pros are using tape.

"Overtightening" because threads are lubed makes no sense to me.

Imagine pushing a v shaped wedge into a v cut opening
in a piece of plastic or metal. *The further in the wedge goes,
the more splitting force you have. *Do you think with the same
amount of force applied to the wedge, it will go in further with
or without lube?

One guy's "feel" for tight isn't the same as another's. *You use a
different length wrench, the feel changes.

Agree. *That's where experience counts. *And why perhaps
those with little experience could wind up in trouble using
Teflon tape while others have used it and it's worked fine.

Likewise, these guys are saying stuff like "2 turns past
finger-tight." *That fine if there's no burrs on the threads, the
threads are consistently formed, and everybody has the same fingers.
That's not realistic. *What's more realistic is a consistent taper and
consistent thread count.
You want to look at how many threads should still be exposed for a
good fit, and tighten to there. lube or no lube. *I can see that with
galvanized and know when the male is inserted far enough .
The force used to get there can vary depending on the thread
condition, but threads exposed is the best indication of what force
the taper is putting on the female, and when to stop cranking down.

And there I disagree. * Joints are tight when they are tight.
If you try to rely on looking at how many threads are showing,
I think you're in for trouble. * How do you even know that the
number of threads is consistent from one pipe to another?
For example, if you get a piece of pipe cut and threaded at
HD, is piece A going to have exactly the same number of threads
as piece B? * You just have to develop a feel for it and learn
from experience.

Actually, two things work in our favor.... threading machines have
automatic stops & molded parts are consistent (and hopefully the
tooling was "proofed").

Of course there is always some variability of the parts & how much
tape (that's dope is better for plastic) but the number of turns to
"make up" after finger / hand tight is pretty consistent.

Pipe threads have a standardized / designed thread form.....well,
unless they come from China

Seriously pipe threads are very consistent unless made by a total hack
shop...which is happening less & less as 3rd world mfrs learn (ie get
parts rejected)

IIRC pipe threads might even have torque limits for "tight
joints"...too lazy to look it up.

cheers
Bob

On Mon, 13 May 2013 20:33:45 -0700 (PDT), DD_BobK
wrote:

On May 13, 12:51*pm, Oren wrote:
On Mon, 13 May 2013 10:51:04 -0700 (PDT), "

wrote:
" professional installers" ??? yeah, right!
from the layout, they look like hacks

+++++1

I wager a hazard, that the pool cost around 200G new.

Depends on when it was built but with that hidden cover storage &
automatic cover.... 200k ain't far off.

He has those pop up cleaners instead of a sweeper / cleaner. Solar on
the side of a mountain, heating, all equipment is on three different
levels (Mt. side). I recall there are 17 or so Jandy vales and three
single speed pump motors in that git up. 200K would be cheap I think.

For giggles some years back I checked prices for a new pool.
Interesting was that if you want pool 15' long, it would cost the same
as a 28' pool. The say it was the base price for 28', regardless.

Contractors here had to have a separate license to build pools. A
"pool contractor license". State law that reduces contractor run
around, to protect folks.

On Mon, 13 May 2013 22:44:51 +0200, nestork
wrote:

I would put a much lighter coat of thread sealant on your male threads.

And, of course, I'd try to be sloppy about it.


Well, Bless your heart! A single Canadian with a sense of humor.

On May 12, 5:00*am, "HeyBub" wrote:
DD_BobK wrote:

I'd use one or the other, not both.

Teflon is primarily a lubricant and is most effective on NPT
fittings. NPT fittings change their pitch so that the connected
pieces deform the pipe threads more and more making the seal.

Other types of threading do not change the thread pitch (if there is
any involved in the seal), so any imperfections are better dealth
with by a pipe sealant.

A lot incorrect information.....

1) Teflon is primarily a lubricant * it is material to seal the
naturally occurring / designed in clearance between internal &
external pipe threads.

2) NPT fittings change their pitch so that the connected pieces deform
the pipe *threads more and more making the seal. incorrect for
ubiquitous / normally used / everyday *NPT threads. *

NPT pipe threads do NOT have interference thread forms, they do not
change pitch.
If they deformed, how could new fittings be used on old pipe?

"Dry fit" pipe threads do exist & do seal based on interference but
they are seldom encountered in daily life.
I used them ~30 year on military hydraulic systems where dope & tape
were prohibited. *Dry seal threads are a bitch to use, they sucked...
a major PITA. *Be thankful that everyday threads are not as you
describe.

Take a look at the wikipedia article on pipe threads.

Likewise, look at the article on thread sealing tape:

"One of the defining characteristics of PTFE (Teflon) is how good it is at
defeating friction. The use of PTFE tape in tapered pipe threads performs a
lubricating function, which more easily allows the threads to be screwed
together, to the point of deformation, which is what creates the seal."

to the point of deformation, which is what creates the seal."

deformation of the threads or the tape?

The crests & valleys of internal & external NPT pipe threads NEVER
touch.
Look at the thread form description in Machinery's Handbook.

The spiral leak path ALWAYS exists, this spiral MUST be seal with a
sealing compound.
You can tighten lubricated NPT pipe & fitting joints 'til you run out
of torque ..the joint will leak unless sealant is used.

On May 13, 5:23*am, Caryn wrote:
On Mon, 13 May 2013 04:43:10 -0700, DD_BobK wrote:
NPT threads need a sealant to seal the spiral leak path.
NPT threads do not seal by thread deformation.

Are the union threads NPT also?

Missed this...

Are the union threads NPT also?

No, threads on unions are some sort of straight thread.
The purpose of the union thread is to provide a means to compress the
seal; o-ring, brass insert or union material depending on design of
union.