What is a Figure-8 Blind?
A figure-8 blind (also called 8-blind or spectacle blind) is a pipe fitting shaped like the numeral “8”. It consists of two discs connected by a narrow waist: one disc is solid (blank) and the other is open (spacer). By rotating the fitting, an operator can either isolate the line (solid side in) or allow flow (open side in). This design enables quick line isolation without removing the fitting or breaking the pipeline.
Figure-8 blinds are commonly used in oil & gas, petrochemical, and power plants where periodic maintenance, cleaning, or safety isolation is required. They differ fundamentally from ordinary pipe fittings because they serve both as a blind and a spacer in one integral unit.
Key Differences from Other Fittings
1. Figure-8 Blind vs. Ordinary Blind (Flat Blind)
- Ordinary Blind: A solid disc bolted between flanges. Once installed, it permanently blocks flow. To change the line status, you must remove the blind and replace it with a spacer or re-assemble the joint.
