Page 24 - Design Criteria.qxd

25 ® Welcome to the Next Generation of Sealing Technology
Spiral Wound Gaskets
FILLER MATERIALS
FLEXICARB®
A high purity flexible graphite with no binders or fillers. It exhibits superior sealability, and excellent resist-
ance to a wide range of chemicals. Its unique combination of low permeability, inherent lubricity, and com-
pressibility make FLEXICARB suitable for critical gas and vacuum service. Leachable chloride content of
industrial grade FLEXICARB is 100 ppm maximum. Available in industrial, nuclear or corrosion inhibitor
grades.
FLEXITE® SUPER
Low chloride filler material, developed by FLEXITALLIC, consisting of a Chlorite mineral with graphite
and acrylic binder. This material may be used for general service applications.
THERMICULITE™
Filler material for use in applications with temperatures as high as 1800°F where graphite material is sus-
ceptible to oxidation. Thermiculite’s sealability is by far superior to mica or ceramic. Wide range of chem-
ical compatibility of Thermiculite makes it suitable for harsh applications such as nitric acid and high tem-
perature NOx gases.
POLYTETRAFLUOROETHYLENE (PTFE)
PTFE is used as a filler material in Flexitallic gaskets where extreme chemical inertness is required. PTFE
is unaffected by any known chemicals except molten alkali metals and fluorine precursors. Because of its
low permeability, PTFE is also frequently used as a filler material on FLEXITALLIC gaskets in vacuum
applications. Gaskets wound with PTFE should be fully confined either by fitting in a groove or providing
both an external and internal ring.
CERAMIC FIBER
Consists of aluminum silicate fiber with an organic binder. This material has a lower sealability compared
to other filler materials, however, it has excellent high temperature stability to 1250°C (2300°F). It resists
attack from most corrosive agents (except hydrofluoric and phosphoric acids) as well as concentrated alka-
lies. Recommended only where conditions preclude the use of Thermiculite filler.
Filler Material Temperature Limits
Flexicarb -400°F to 900°F
Thermiculite 835 -300°F to 1800°F
Flexite Super -150°F to *
PTFE -300°F to 500°F
Ceramic -150°F to 2300°F
* Although Flexite Super has successfully been used at
elevated temperatures we recommend that you consult our
engineeering department for specific applications.