The standard manufacturing thicknesses for spiral wound gaskets are 3.2, 4.5 & 6.5 (measured across metallic strip not including the filler which protrudes 0.2 : 0.3 mm beyond the metal
Large bore piping divided to 3 types
a- standard schedule(thickness 4.75mm to 9.53mm)
b- high schedule(thickness 9.54mm to 19mm)
c- critical schedule(thickness more than 19mm)
Each type different in the shape of welding groove