Definition of blind flange 

A Blind flange is round plate which has all of the relevant boltholes but no center hole, and because of this feature this flange is used to close off the ends of a piping systems and pressure vessel openings. It also permits easy access to the interior of a line or vessel once it has been sealed and must be reopened.

The blind flange is mainly used to completely isolate the production medium to prevent the loose closure of the cut-off valve from affecting production or even causing accidents. The blind flange should be set in the parts requiring isolation, such as the equipment nozzle, before and after the cut-off valve or between two flanges, usually recommended to use 8 type blind flange; Insert flange (circular blind flange) can also be used for pressure, purging and other disposable parts.

The function and classification of blind flange

In appearance, blind flange is generally divided into flange blind flange, 8-shaped blind flange, insert flange, and pad ring (insert flange and pad ring blind to each other). Blind flange plays the role of isolation, cutting, and head, pipe cap, welding plug plays the same role. Because of its good sealing performance, it is generally used as a reliable means of isolation for systems requiring complete isolation. A flange blind is a solid circle with a handle for normally isolated systems. The figure 8 blind flange, shaped like figure 8, is a blind flange at one end and a throttle ring at the other end, but the diameter is the same as the pipe diameter, does not play the role of throttling. 8 figure blind flange, easy to use, use the blind flange end when isolation is required, use the throttle ring end when normal operation, but also can be used to fill the installation gap of the blind flange in the pipeline. Another feature is the obvious logo, easy to identify the installation status.

The production process of blind flange

Generally divided into 2 kinds: forging  and casting. The price of forging products is the higher,casting is the lower. The density and stable performance are better if flange made by forging. Currently the forged flanges are most Popular.We produced all flanges by forging.

Blind Flanges are commonly used in petrochemical, pipe engineering, public services & water works.

Blind pipe flanges are often used for high pressure applications. 

This reduction can be a threaded reduction or welded reduction.

• Size: 1/2” to 60”, DN 12mm to DN 1500mm

• Pressure class: Class 150 to Class 2,500, PN 2.5 to PN 250

• Facing: RF / RTJ

Material:

• Cabon steel: A105, A350 LF2

• Stainless steel: A182 F304/F304L/F316/F316L/F321

• Alloy steel: F11, F12

Specifications:

Blind flange is put at the end of pipe or at the junction that would possibly be a future expansion into that direction.

Piping is easier to drill or weld at the construction stage. Once it was in use, drilling or welding will need prolong cleaning especially when the fluid transferred is combustible. For the mean of future extension, either the blind or valve would be used to seal the end.

Advantage of Blind Flanges

• A much more cost efficient way to seal a pipe when doing repairs

• Blind flanges are convenient to install

• They can save a good amount of time and money