Class 600 Spectacle Blinds

Class 600 Spectacle Blinds are heavy-duty isolation devices for high-pressure piping systems. The increased disc thickness at Class 600 results in substantially heavier assemblies that may require mechanical assistance for rotation. The bar connecting the two discs must be designed to support the full weight of both discs without permanent deformation.

At Class 600, the blind disc thickness can exceed 1.5 inches for larger pipe sizes, and the total weight of the spectacle blind assembly for NPS 12 and above may require a small crane or chain hoist for handling during turnarounds. Rigging attachment points are sometimes incorporated into the connecting bar design.

These spectacle blinds are used in high-pressure hydrocarbon processing, steam systems, and chemical synthesis piping where positive mechanical isolation is required by safety procedures. ASME B16.48 specifies the dimensional requirements, and the blind disc is typically designed per ASME Section VIII pressure vessel code principles.