Style HKWOI with the addition of an inner ring. The inner ring also serves several functions. Primarily, it provides radial support for the gasket on the I.D. to help prevent the occurrences of buckling or imploding.
Its I.D. is normally sized slightly larger than the I.D. of the flange bore,
minimizing turbulence in process flow. The inner rings are normally
supplied in the same material as the spiral wound component. Spiral
wound gaskets to ASME B16.20, designed to suit ASME B16.5 and
ASME B16.47 flanges.