What is spectacle blind flange?

Spectacle blind flange also called figure-8 blind flange.The “8” character blind plate is named for its shape,similar like an 8-character.It is used to isolate or connect piping systems. The “8” blind flange is a steel plate with fixed thickness divided into two plates.Two plates are connected by flat steel,one of which is a solid plate and the other is a hollow ring. The inner aperture of the plate is the same as that of the flange.

The two parts of the spectacle blind flange could be separated to be used,the blind part of the spectacle flange is called spader or paddle,it is used to block the flow fluid in the piping system.The opening part of spectacle flange is called spacer or ring spacer,when it is worked in the two flanges,it will not block the fluid running.Commonly the spader or spacer should have a section of steel handle for control easily.

Spectacle blind flange picture

1.The “8” character blind plate 2.flange  3.gasket 4.stub bolt

How to use spectacle blind flange?

In pipeline system,spectacle blind flange usually needs to be isolated from other facilities or devices.Usually,it is located in the open position so that the fluid can pass through the pipeline.When it is in the closed position,the pipeline is closed and the fluid is blocked.Maintenance of the pipeline system is one of the reasons that it rotates to the closed position.There is a drill hole in its connecting web,when loosening and disassembling some bolts,spectacle blind can rotate between flanges.After replacing the gasket, the bolts can be reassembled and fastened.

Figure 8 flange or spectacle blind flange used in piping system

The specification of figure-8 blind flange:

Haihao Group can supply figure-8 blind flange according to standards:ANSI/ASME B16.5,B16.47,B16.36,BS 4504,DIN 2527,MSS SP44 etc.The products’ size from 1/2″ to 48″.We can manufacture carbon steel,stainless steel and alloy steel figure-8 blind flange,the materials as follows:

Stainless Steel: ASTM A182 F304, F304L, F304H, F316, F316L, F316Ti, F310, F310S, F321, F321H, F317, F347, F347H, F904L etc.
Duplex Stainless Steel: UNS S31803, UNS S32750,S32205,S32760,F51,F52,F60,F55 etc.
Carbon Steel: ASTM A105,A350 LF2,SS400,P235GH,P250GH,C22.8,16Mn,20# etc.
Alloy Steel: ASTM A182 F5,F9,F11,F12,F22,F91 etc.

RTJ stainless steel A182 F304 spectacle blind flange

Haihao Group manufacture all types flanges(weld neck flange,blind flange,slip on flange,lap joint flange,socket weld flange,threaded flange,orifice flange,reducing flange,tube sheet,anchor flange etc) and steel pipes,butt welding pipe fittings,forged pipe fittings.If you want to have more information about flanges products or you want to share your opinion with us,contact us at:sales@haihaogroup.com