I have a bunch of white Teflon pipe thread tape. I wanted some
thicker tape and the only thing I could find at the store was the
usual thin white stuff for water lines and some thicker stuff that was
yellowish in color and labeled for use on gas, kerosene, LPG. Doesn't
say anything about water. The white stuff doesn't say what kind of
liquid but does say for use on pipe threads.
I assumed there was some actual difference between the two making the
white stuff unsuitable for gas lines. But I just looked at them and
they are all labeled as MIL-27730A . Seems like the only difference
is one is colored yellow and is a little bit thicker.
Anyone know why the one claims to be for gas when it's listed as the
same mil spec as the white?
Mainly because of the thickness.
When PTFE (Teflon) tape first became available they only made it in the
common single density type, which we commonly find in the hardware and home
supply stores. Later they began making a double density version, which was
twice as thick. Many state and local codes then adopted the double density
type as mandatory when making connections for natural gas however since both
products were the same color (white) it was difficult for inspectors to be
sure which product had been used. PTFE tape is now made in numerous
varieties and they have issued a color standard to determine which type
should be used.
WHITE-Single density- should only be used on NPT threads up to 3/8 inch.
YELLOW- Double Density- yellow double density is often labeled as "Gas type"
RED-Triple Density: (Note-the container is red but the tape itself appears
as a pale pink color). Presently required on all joints ?" diameter or
GREEN- Oil Free PTFE tape- Required for use on all lines conveying oxygen
(I.E. -medical oxygen or welding oxygen lines).
COPPER COLOR- contains granules of copper and is to be used as a thread
lubricant but is not approved as a thread sealant. (Generally it is used as
a thread lubricant on bolts or pipe threads for mechanical applications
where no physical seal is required.)
PTFE tape is only approved as a thread seal when applied correctly. To apply
you begin at the end of the pipe and wrap the tape under tension in the
direction of the thread turns. Each successive layer should overlap the
previous layer by ? to 2/3 and continue wrapping until the entire threaded
portion of the pipe is covered. (Minimum of 3 full turns).
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I wouldn't buy that.
It seems to me that all teflon tapes are made of the same stuff; teflon.
So, if the thin white stuff "flakes off" in the presence of natural
gas, then you'd expect that every tape made of teflon would do the same,
only perhaps to a greater or lesser extent.
Also, the gas piping code requires a sediment trap be installed after
the gas shut-off valve but before the gas valve of each gas appliance:
The whole idea here is that any dirt or foreign matter in the gas stream
would accumulate in the trap instead of clogging up the gas valve to the
appliance. If teflon tape were to "flake off", then it would be common
knowledge that these traps would contain particles of teflon tape, and
I've never heard of that before.
"rbowman" <> wrote in message > Stormin Mormon
Yes, the problem is that some people allow the
to 'overhang' the end of the threads. The first
should be visible. Any overhang will get extruded
the connection and a string will head downstream
'Phil Kangas[_4_ Wrote:
> ;3321382']"rbowman" wrote in message Stormin Mormon
I dunno. I wouldn't expect to find that in a DIY'ers work. Generally,
what you find is that DIY'ers will go out of their way to do things as
carefully as they can when they're working on their own house, so as to
avoid problems like gas or water leaks later. They'll be as careful
wrapping those threads as you would expect of anyone wanting to ensure
they stand the best chance of avoiding a possible leak.
Not saying it can't happen... but I wouldn't expect that of a DIY'er
working on a project in his own house.
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