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The physical and chemical
properties of the Fluoroplastic material to be
used for lining is to be evaluated in terms of
service requirement. Overall parameters for
maximum operating temperature and pressure,
along with corrosiveness of service fluid will
determine liner and metallic shell material.
Chemical properties of the
lining material will determine its
compatibility with service fluid being handled
under the specific operating condition of
temperature and pressure. Correct processing
technique & design parameters for the size of
liner determine the overall performance of the
lined items.
Physical properties of the
lining materials and its processing technique
will determine the reaction of liner to
temperature / pressure combination vis-a-vis
permeability and absorption capacity.
Permeation would cause
corrosive fluid to attack the shell metal and
corrode it even though the lining material
itself is unaffected.
Gases and vapours
permability through fluoroplastic material at
a greater rate as pressure and temperature of
the system becomes higher and higher. The
molecules of gas and vapour migrate through
the polymer, either by passing through
microvoids in the polymer or by passing in
between polymer molecules resulting in
corrosion of shell and thereby failure of the
system.
Process of permeability can
be controlled by processing the liner as dense
as possible. Higher the specific gravity of
the liner, lesser the permeation. A typical
example of high permeation is chlorine and
hydrogen chloride gas under pressure and at
elevated temperature.
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