Chemical Engineering February 2016 - 23

Trelleborg Sealing Technologies
Garlock Sealing Technologies
Figure 3. A PTFE-based sealing product, Turcon
Variseal Ultra-Clean from Trelleborg, was developed
to stand up to the harsh environments
created by CIP, SIP and other high-temperature,
aggressive sanitary environments
step is to take those materials and designs,
innovate and improve the existing
properties, which are already very
good, and make them even better. "
And, for each challenge, there is
often an innovative solution available.
Reducing emissions
It's no secret that EPA continues to
tighten regulations regarding allowable
limits on emissions of all types
of pollutants. As part of the regulatory
requirement, processors must
have programs in place to measure
and monitor emission levels at potential
points of emission, such as
valves and flanges, and if they find
a component leak above a certain
level, they are required to fix it. " This
can be a costly method that requires
a lot of labor, but it's very effective, "
notes FSA's Azibert.
One of the ways to reduce the
emission level at any given point,
and, in turn, reduce the amount of
effort to remain in compliance, is to
employ specialized low-emission
(low-E) sealing solutions in problem
areas, says Ron Frisard, field product
manager, stationary equipment,
with A.W. Chesterton.
He says that using certified low-E
valve packings, like Chesterton 1622
valve packing (Figure 1), can help reduce
fugitive emissions from valves.
This high-performance, graphite
valve-stem packing blocks valve fugitive
emissions to below consent
decree requirements. A non-hardening,
flexible packing, constructed
from Inconel-reinforced mesh with
internal exfoliated graphite, it will
not shrink or absorb moisture. The
single-spool solution reduces invenFigure
4. Garlock's THERMa-PUR is a proprietary new
gasketing material designed for use in high-temperature
sealing applications. It provides sealing at temperatures
up to 1,832°F, where gaskets of other materials, such as
graphite, cannot survive
tories and installation errors caused
by using multiple types of rings in
various orientations. It is suitable for
use in a variety of applications to seal
light and heavy hydrocarbons, VOCs
and most non-oxidizing chemicals
in the hydrocarbon processing and
chemical industries.
Designing for harsh processes
" One of the biggest concerns about
sealing components in the chemical
industry is their ability to stand up to
corrosion and to resist chemicals, "
notes Azibert. " There are different
materials for these applications and
manufacturers continue to develop
fillers and new formulations on the
existing products to keep up with the
demands of the process industry. "
Uwe Kannengiesser, global technical
coordinator and key account
manager for Vestakeep, with Evonik
Industries AG (Essen, Germany;
www.evonik.com), agrees. " There is
an increasing demand for a material
that can operate in a high-heat
environment, but also provide excellent
resistance against corrosive and
chemical media. In addition, the material
has to offer higher service lifetime
for a significantly longer interval
between maintenance, " he says.
For example, he says that for back
valve rings and compressor plates
there is a need for ductile material
with higher fatigue resistance.
ChemiCal engineering www.Chemengonline.Com February 2016
" This is because brittle material has
been found to fail in shorter operation
times as it has a poor resistance
against dynamic stresses, " he says.
" Another criteria gaining importance
is the wear resistance of the material.
A low sliding coefficient translates
into low energy consumption. "
To meet this myriad of requirements,
Evonik has developed Vestakeep
5000 (Figure 2), which is a
ductile polyetheretherketone (PEEK)
available as a granule for injection
molding and extrusion to fulfill the
design challenges for seals and gaskets.
A recent development on that
initial material, Vestakeep 5000 HCm,
can also be adapted to improve the
sliding and wear resistance needed
in some applications.
Polytetrafluoroethylene (PTFE) is
another material commonly used
to meet the demands of the CPI,
including chemical resistance, and
sealing product manufacturers are
constantly developing new formulations,
blends and configurations to
stand up to challenging conditions,
such as higher temperatures, hazardous
chemicals and other harsh
conditions. For example, Garlock's
Gylon Stress Saver Style 3504 combines
the Gylon Style 3504 PTFE
gasketing with aluminosilicate microspheres,
which provides a tighter
seal over conventional PTFE. The
Stress Saver family of products is
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Chemical Engineering February 2016

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