SUPREME AQUA GOLD MOULDED PIPE FITTINGS - SCH80 Blind Flange Sch - 80 (Size-65mm) - In essence, a blind flange is a flange without a hub or a drilled centre. Blind flanges feature a comparable bolting pattern, the same face type, and the same face thickness as a flange. Moreover, a pressure vessel's nozzle aperture can be sealed with blind flanges.