Spectacle Blinds, Spades & Spacers — ASME B16.48

What are Spectacle Blind, Spade & Spacer?

ASME B16.48 covers operational line blanks installed between ASME B16.5 flanges. A spectacle (figure-8) blind joins a solid blank and an open ring with a web; it is rotated to switch a line between closed and open, and the visible position shows the line status. A paddle blank (spade) is a single solid plate with a handle, and a paddle spacer is an open ring of the same thickness that keeps the flange gap when the blank is removed. Blank thickness depends on class and size so that it withstands full line pressure.

Key features

• Spectacle (figure-8), paddle blank and paddle spacer types
• Thickness to ASME B16.48 for the class and size
• RF faces for spiral wound gaskets, or RTJ grooves
• Handle or web carries identification marking
• Matched to ASME B16.5 flange bolt pattern

Specification

Applications

• Positive isolation for maintenance and confined-space entry
• Process unit battery limits
• Pump and compressor isolation
• Tank inlet and outlet isolation
• Hydrotest isolation during commissioning

Spectacle blind vs paddle blank and spacer

A spectacle blind keeps the blank and spacer together, so the line status is always visible and the spare is never lost; it suits frequently switched lines in smaller sizes. In large sizes a spectacle blind becomes heavy and awkward to rotate, so a separate paddle blank and paddle spacer are used and swapped as needed. Both arrangements use the same thickness rules in ASME B16.48 for a given class and size.