Spectacle Blind (Figure-8 Blank & Spacer Flange)
Engineering definition, metallurgical mechanisms, standard testing specifications, and manufacturing guidelines for closed-die forgings up to 50 kg.
Quick AnswerFeatured
A safety piping isolation device resembling a pair of spectacles, consisting of one solid disk (blind) and one hollow ring (spacer) connected by a central metal web.
Technical Explanation & Metallurgical Principles
Spectacle blinds (ASME B16.48) provide visible positive physical isolation of piping sections during maintenance or plant turnarounds. Plant operators can see at a glance whether the line is open (spacer in position) or blanked off (blind disk in position), eliminating human valve error in chemical refineries.
Key Engineering Specifications & Parameters
| Technical Parameter / Metric | Engineering Benchmark / Value |
|---|---|
| Designation | Figure-8 Spectacle Blind (NPS 1/2" to 24") |
| Pressure Scope | Class 150# to 2500# (PN 20 to PN 420) |
| Alternative Style | Paddle Blind & Paddle Spacer for heavy sizes |
Application at Jayesh Forge (Rajkot Plant)
Forged and CNC-profiled in carbon steel, 316L, and Duplex strictly up to 50 kg for oil refinery turnaround safety.
Related Materials, Standards & Products
Applicable Material Grades
Related Metallurgical & Testing Terms
Blind Flange (ASME B16.5 & DIN)
A solid circular forged disk with bolt holes but no central bore, used to terminate the end of a piping run, valve nozzle, or pressure vessel inspection opening.
ASME B16.5 Pipe Flanges Standard
The definitive American standard covering pressure-temperature ratings, materials, dimensions, tolerances, marking, and testing for pipe flanges NPS 1/2 through NPS 24.
Raised Face (RF Flange Facing)
A raised annular gasket sealing surface elevated 1/16" (1.6mm) or 1/4" (6.4mm) above the flange bolt hole circle.
Questions Regarding Spectacle Blind (Figure-8 Blank & Spacer Flange)
Valves can leak through worn seats or be opened accidentally by personnel; a spectacle blind provides absolute, foolproof physical line isolation.
Request a Forging Quote with Spectacle Blind (Figure-8 Blank & Spacer Flange) Compliance
Our Rajkot metallurgy desk is ready to review your technical drawings, testing protocols, and delivery schedules for custom closed-die forgings strictly up to 50 kg.