What is a Figure-8 Blind?
In industrial piping, a figure-8 blind (also known as a spectacle blind or spectacle flange) is a single-piece fitting that combines a solid blind and a spacer ring in a figure-eight shape. It serves as a positive isolation device, allowing operators to quickly switch between open (flow) and closed (no flow) positions without disassembling the pipeline. Unlike decorative room dividers, these are heavy-duty components designed for high-pressure, high-temperature services in oil & gas, chemical, power generation, and other process industries.
Applications
Figure-8 blinds are used in:
- Pipeline maintenance and shutdowns
- Test loops and temporary bypass lines
- Safety isolation of equipment (pumps, valves, heat exchangers)
- Positive isolation during hydrotesting
- Systems where frequent line blinding is required
Standards to Confirm
When procuring figure-8 blinds, ensure compliance with:
- ASME B16.48: Standard for line blinds (figure-8 type)
