[TheForge] teflon, ice rink, leaks, etc.

[Paul Sperbeck]

Let me say that this comes form a plumber with 42 years experience... 
the lay public has no idea how to use teflon tape correctly. Most of the 
time I see 4 layers of tape with layers extending over the end of the 
male thread. When you screw this in you cut off the overhanging ends 
which then distribute themselves in all the wrong spots in your piping 
system. Too much tape, which is nearly incompressible, can also cause 
the fitting to stretch and fail.

The tape you see on tank valves and professionally assembled fittings 
does not extend over the end of the pipe of fitting. We usually start 
back about 1/2 to 1 thread from the end, only apply one  to 1-1/2 layers 
of tape and use the correct tape for the application.

Correctly installed, the amount of teflon tape exposed to the gas flow 
is on the order of 0.00004 square inches. Adiabatic compression which 
can result in autogenous ignition of the  teflon is extremely unlikely 
due to the quenching effect of the surrounding metal and the cooling 
which takes place as the gas travels along the spiral path of the 
thread. One can cannot say 'never' but I I think that I would in this 
case...

Teflon correctly used is not meant to repair bad threads or loose 
fitting nuts and ferrules. I don't much care what you do on water 
systems, but high pressure gases are no joke.

For another high pressure gas application see:
http://www.quackenbushairguns.com/index.htm
more than one way to get hurt...

paul
WB9HCO
-- 
Try to notice the thing that happened just before the thing
you didn't want to have happen happened!

Resistance Is Not Futile!
It's voltage divided by current.

No trees were killed in the generation of this message,
  but a tremendous number of electrons were terribly inconvenienced



On 11/21/2012 07:34 AM, Cindy and James wrote:
> I'd have to look again but seems to me that I see teflon tape around 
> the threads of the valves of most cylinders where the valve screws 
> into the body of the cylinder.  OTOH I understand that you don't want 
> any foreign substances - teflon or otherwise - in your regulator.
> James
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