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PTFE (polytetrafluoroethylene,
better known as
Teflon®) and it’s derivatives like
FEP and PFA,
is one of the most
inert
and
chemically resistant
materials that an o-ring or seal
can be made from. It has been
described as the
“slipperiest stuff in the
world”
because of its very low coefficient
of friction.
There are some elastomers today
that approach PTFE’s chemical
and
heat
resistance but their high cost can be a drawback. PTFE can be modified with
fillers to improve its
properties depending on the
applications requirements.
PTFE O-rings are typically used
in static applications while
PTFE lip seals
(with metallic springs or rubber
used as an energizer) and
piston rings
will be used in
tough dynamic applications where pressure and heat or high cycles are a problem. PTFE
also makes excellent
Backup Rings
that boost the sealing
capabilities of an o-ring to
much higher levels. It is also
possible to
encapsulate
an elastomeric ring with a
seamless FEP tube creating a
unique o-ring with the
properties of both the elastomer
and the PTFE.
PTFE can be extruded, skived
into thin tape or sheet, and
molded by several processes
depending on the outcome
desired. It is also readily
machineable, lending itself to
special parts
and configurations to suit the
application at hand.
Ball valve seats
are a common use for PTFE both
molded to near net and machined
for special or low volume
requirements.
PTFE can now be processed into
soft joint sealing tape and
gaskets
by a special “expanding” process
allowing its use in applications
where a flange or sealing
surface is less than ideal or
needs a low bolt loading such as
glass flanges.
Other
engineering plastics such as:
UHMW
(Ultra High Molecular
Weight Polyethylene),
Nylon®,
Delrin®,
PEEK®
(Polyetheretherketone),
can be supplied in sealing
configurations as well as
machined parts. Give us a call
and we will be glad to help you
with any sealing problem that
might require a “plastic” or
PTFE solution. |
