A blind flange is a round plate which has all of the relevant blowholes except center hole, and because of this feature the blind flange is usually used to close off the ends of a piping systems and pressure vessel openings. It also permits easy access to the interior of a line or vessel once it has been sealed and must be reopened.
Without the blind flange
it would be difficult to perform maintenance or repairs on a pipeline. The flow would need to be shut off at the nearest valve, which could be miles away from the repair area. Valves are also very expensive and are prone to sticking. The blind flange is a much more cost efficient way of sealing a pipe.
Blind Flanges are commonly used in petrochemical, pipe engineering, public services and water treatment etc.