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A spiral-wound gasket
is made of alternate plies of V-preformed hoop and soft filler
that are tightly and spirally wound together. The metal winding
around the entire inside and outside circumferences of the gasket
is spot welded. Normal practice is to reinforce the inside and
outside diameters with several plies of the metal winding without
a filler being introduced. According to the need of the mating
flange, the gasket is provided with an outer ring, an inner
ring or both outer and inner rings.
The outer ring serves as a compression stop, anti-blowout
device, which properly centers the gasket on the flange. The
inner ring acts as a compression stop and is used to fill
the annular space between the flange bore and the gasket inside
diameter to minimize turbulence of process fluids and erosion
of flange faces.
On rare occasions, applications for spiral-wound gaskets
arise where it is necessary to utilize a spiral-wound outer
and/or inner ring. The spiral-wound outer or inner rings are
used primarily as reinforcement and are chosen instead of
a solid metal ring, because of lower costs or because of limited
space when the use of a solid metal ring would be prohibited
due to the difficulty in fabrication or usage.
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