Chemical Engineering October 2015 - 98

Sealing Technology 2015 Special Advertising Section
PTFE gaskets reinvented
Durlon 9000 from Triangle Fluid Controls uses PTFE and glass to its best advantage,
to bridge the gap between cold flow and sealability
TFE gaskets generally get a bad rap
because of inherent cold-flow properties
of the base material, notes gasket
specialist Triangle Fluid Controls.
Manufacturers have therefore come up
with several ways of modifying PTFE in
order to combat creep, ranging from adding
various fillers to expanding the material
in one or more directions.
Regardless of these efforts, PTFE gaskets
continue to creep. But one physical
property does not a gasket material make.
Gasket material properties are holistic -
much like system pressure, temperature,
flow, and line size.
P
Since its inception more than 25 years
ago, the company's Durlon 9000 has been
engineered to deliver the best performance
based on the interaction of all physical
properties within any given application.
Simply put, Durlon 9000 is designed to be
the ultimate universal PTFE pipe gasket.
Expanded PTFE (ePTFE) resists creep,
but its lack of recovery quickly becomes a
safety liability. To eliminate creep, ePTFE
Gaskets made from Durlon 9000
must be compressed to nearly the thickness
of a piece of paper, significantly reducing its
ability to recover from system fluctuations.
Durlon 9000, on the other hand, balances
creep properties with recovery properties to
maintain its original seal.
Durlon 9000's engineered filler system
incorporates a homogeneous dispersion
of solid architectural glass which provides
superior physical and sealing performance
over hollow glass and other fillers. Solid architectural
glass gives the gasket enhanced
structural integrity and low uncompressed
porosity, allowing Durlon 9000 to be used
in aggressive chemicals and at both reasonably
high and very low flange loads.
Silica-filled PTFEs, in contrast, are hard
and require significant flange load to seal
tightly. ePTFEs feel soft but still require relatively
high flange loads to seal their internal
porosity. Durlon 9000 bridges these concerns
while providing long-term sealability
and reliability.
Another advantage to Durlon 9000 is
that unlike calendered and ePTFEs, which
are only available in fixed sheet dimensions,
Durlon 9000 is skived from a large billet and
can be made longer than a regulation NFL
football field. This continuous profile allows
larger one-piece gaskets, improves yield for
gasket cutters, and cuts prices to end users.
Durlon 9000 is PTFE reinvented.
www.trianglefluid.com
Expansion joints with ASME B16.47 Series B flanges
Proco Products explains two ways to accommodate ASME B16.47 Series B flange drilling
when specifying rubber expansion joints
" P
iping system designers: Have you
ever come across the need to supply
rubber expansion joints/control units
in a piping system where the flanges have
ASME B16.47 Series B drilling? " asks Proco
Products. " If so, you will know that the
conventional control rod setup can be challenging,
since the attachment area for a
traditional triangular control rod plate
is greatly reduced. " This is because with
Series B drilling the bolt circle for the flange
is closer to the O.D. of the pipe than it is for
Series A drilling, Proco explains.
For example, say a designer has an application
for a 30 in. I.D. X 24 in. OAL triplearch
rubber expansion joint, where one end
has ASME B16.47 Series A drilling and the
other end has ASME B16.47 Series B drilling.
Control rods are used in this example
as the piping system is unrestrained.
For ASME B16.47 Series B drilling, the
best rubber expansion joint design is an
" interior tie rod " type. This uses a thicker
ring/rod plate to connect the expansion
joint to the adjacent mating flange, while
connecting rods control the thrust loads
and movement of the expansion joint under
pressure. This design eliminates the compli(Left)
Interior tie rod rubber expansion
joint design for ASME B16.47 Series B
flange connection
98
cation of a traditional control rod setup on
the back side of the mating flange, where
clearance of the I.D. of the control rod plate
aligning with the mating flange holes becomes
difficult (illustration, left).
The only other option when dealing with
ASME B16.47 is a control rod setup with
thick fabricated split flange plates, so that
the resultant thrust loads from the rubber
expansion joints are evenly distributed to
every bolt hole (photo, below). However,
the " interior tie rod " configuration is preferred.
www.procoproducts.com
Exterior
control unit design
ChemiCal engineering www.Chemengonline.Com oCtober 2015
http://www.trianglefluid.com http://www.procoproducts.com http://www.Chemengonline.Com
Chemical Engineering October 2015

Table of Contents for the Digital Edition of Chemical Engineering October 2015
