Spectacle Blind Flanges

A spectacle blind is a combination of a single blind (solid plate) and a ring spacer manufactured, for field convenience, as a single unit. A spectacle blind is a safety device used to isolate a section of line or a piece of equipment when the line or equipment needs to be inspected or removed from service. It is different from a valve in that the blind is a permanent or long term isolation device.

Weight limitations and the associated difficulty of handling heavy pieces in the field are the primary considerations in specifying a spectacle blind over separate components. Normally, a spectacle blind is mounted in the open position so that flow through the pipe is possible. Maintenance in a pipesystem can be a reason to rotate the spectacle blind in the close position so that the pipe is blanked off and no flow is possible. This run will take place through the hole drilled in the connection piece. By loosening all the bolts and removing part of them, the spectacle blind can be rotated in the chosen position. After placing new gaskets, the bolts can be reassembled and tightened.