ASTM A182 F316L Stainless Steel Spectacle Blind Flange / Figure 8 Flanges

ASTM A182 F316L Stainless Steel Spectacle Blind Flange / Figure 8 Flanges
 
 
A spectacle flange / figure-8 blank, is a safety device used to isolate a section of line or piece of equipment when the line or equipment needs to be inspected or removed from service. It is different than a valve in that the blind is a permanent or long term isolation device. It is machined from a single piece of metal that is cut to match the pipe size, fit between two pipe flanges and requires an additional gasket when it is installed. Also, the bolts will need to be lengthened depending on what piping class and size blind is used. The thickness of the spectacle blind is specified based on the line pressure and pipe size.
 
 
One end of the blind will have an opening to allow flow through the pipe during operation and the other end is solid to block flow during maintenance. They are generally installed as a permanent device to separate process piping systems. is essentially a simplistic valve which fits in the line between two flanges and is bolted in place. One side of the Spectacle Blind is open (spacer) and the other side of the Spectacle Blind is blanked (blind or spade).
 
Equivalent Grades

 
 
Forged and Plate Flanges

 
 
SS 316L Flange Standards / Types And Pressure Class

 
 
Application
Natural gas,chemical,petroleum,ship building,marine,paper making, metallurgy, electric, power, boiler , etc.
 
It is used usually for maintenance when it is required to isolate a section of pipe or isolate a device. Because this is a semi-permanent isolation it is very safe and safety is often the mentality behind the use of a Spectacle Blind in maintenance operations.