On Sat, 13 Dec 2014 23:19:05 -0500, "Ralph Mowery"
wrote:


"Ashton Crusher" wrote in message
.. .
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 ½" diameter or
greater.
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 ½ to 2/3 and continue wrapping until the entire threaded
portion of the pipe is covered. (Minimum of 3 full turns).



---
This email has been checked for viruses by Avast antivirus software.
http://www.avast.com


Thanks.