Page 84 - GarlockFluidSealing2010

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Factors Affecting
Gasket Performance
A gasket has one basic function: to create a positive
seal between two relatively stationary parts. The gasket
must do a number of different jobs well to function prop-
erly: frst, create an initial seal; second, maintain the seal
over a desired length of time; third, be easily removed and
replaced. Varying degrees of success are dependent on
how well the gasket does the following:
1. Seals system fuid.
2. Chemically resists the system fuid to prevent serious
impairment of its physical properties.
3. Deforms enough to fow into the imperfections on the
gasket seating surfaces to provide intimate contact
between the gasket and the seating surfaces.
4. Withstands system temperatures without serious
impairment of its performance properties.
5. Is resilient and resists creep enough to maintain an
adequate portion of the applied load.
6. Has suffcient strength to resist crushing under the
applied load, and maintain its integrity when being
handled and installed.
7. Does not contaminate the system fuid.
8. Does not promote corrosion of the gasket seating
surfaces.
9. Is easily and cleanly removable at the time of replace-
ment.
During the gasket product selection process that fol-
lows, we recommend that these nine (9) factors be used
as a checklist from the viewpoint of the user’s degree of
need for each factor and the manufacturer’s degree of
compliance.
Gasket Selection
Selecting gasketing materials for particular appli-
cations is not an easy task. The variables present in a
fanged connection seem endless and yet all of them must
be taken into consideration to assure a proper seal. In
the past, the acronym "TAMP" (Temperature, Application,
Media and Pressure) seemed to give suffcient information
to make a gasketing recommendation. Today, items such
as: the fange metallurgy, the amount of bolt thread em-
bedment, the amount of fange rotation, the amount of bolt
stretch, the additives to the media and the fange surface
fnish (in addition to other variables) determine how well
a gasket will perform. In general, the defnition of what a
seal is has changed drastically over the years. Leakage
measurements have gone from drips a minute to parts per
million.
This catalog is designed to help guide you through the
various gasketing products and narrow your choices. All
industry standard tests are included in order to allow an
end user a means of comparison between different materi-
als. Many of the test procedures require that the tests be
conducted on 1/32" material. As a rule of thumb, gasket
performance decreases as material thickness increases.
In addition, compressive loads must be increased with
thicker materials. Proper bolting sequences are neces-
sary to ensure those compressive loads are uniform. The
temperature, pressure and P x T ratings are all based on
optimum conditions. When approaching those extremes, it
is suggested that you consult with the Garlock Applications
Engineering Department or possibly upgrade to a material
that has higher ratings.
As industry standards change and new products
are introduced, this catalog will be updated. In the mean-
time, we urge you to take advantage of our experienced
personnel for assistance. In-plant training, instructional
video tapes, additional technical information and gasketing
recommendations all are available to help in your selec-
tion process. Please feel free to call, fax, write, or e-mail
us should you have any questions or concerns. Garlock is
here to help.
Questions? Call Gasket Applications Engineering
at 1-800-448-6688
WARNING:
Properties/applications shown throughout this brochure are typical. Your specifc applica-
tion should not be undertaken without independent study and evaluation for suitability.
For specifc application recommendations consult Garlock. Failure to select the proper
sealing products could result in property damage and/or serious personal injury.
Performance data published in this brochure has been developed from feld testing,
customer feld reports and/or in-house testing.
While the utmost care has been used in compiling this brochure, we assume no respon-
sibility for errors. Specifcations subject to change without notice. This edition cancels
all previous issues. Subject to change without notice.
GARLOCK is a registered trademark for packings, seals, gaskets, and other products
of Garlock.