spiral wound gaskets uses expanded graphite tape as the filler material which provides superior sealing ability even under  severe conditions such us high temperature, high pressure, cryogenic temperatures,
heat cycles, and temperature cycles.
Types:

a) R type: spiral winding only

b) IR type: spiral winding with inner ring

c) CG type: spiral winding with outer guide

d) CGI type: spiral winding with outer guide and inner ring.