A blind flange is used to block a pipeline and to create a stop or for access in cleaning or drainage. Can also be used in manways. Moreover, the gasket is bolted into the mating surface.

What are Blind Flanges? What do Blind Flanges Do?

Blind flanges are used to stop or close the pipeline. Therefore, it doesn’t have any way for fluids to pass through. 

A blind flange is essential to repair and perform maintenance activity on a pipeline. It helps shut the flow at the right time and save miles of pipeline from damage. It is widely used in construction pipelines. 

Moreover, the process of repair and replacement is more straightforward with blind flanges. You can now assemble the pipes from across the globe and send them to the site. Once these flanges are made, they can easily be bolted and carried on with the repair process. 

Where Do You Use Blind Flanges?

A blind flange is also known as a closure plate flange. It is inserted at the end of the piping to stop the flow. However, it has no hole in the center to allow the flow of fluids or gases. It is usually used for isolating a valve or pipe. Moreover, you can also use it to separate a pressure vessel.

These flanges are used to test pipe pressure and seal the pipe temporarily. It is also used as an access point to the piping system. It also helps create a long-term seal on the piping system, blocking it forever. It is bolted and not welded in a particular place. 

What are the Types of Blind Flanges

There are various types of Blind flanges to choose from. A few of them are as follows:

  • Raised face blind flanges 

These are the most popular and commonly used blind flanges. A raised face blind flange sits against the pipe. Hence, it prevents leakage and tightens the flange bolts. These are helpful in low pressure and are budget-friendly compared to other flanges.

  • Ring joint blind flanges

These types of blind flanges are best to use in high-pressure environments. There is a ring groove attached to the flange’s face. The track holds the gasket in place. Hence, the ring joint blind flanges are a substantial wall and can be used in high temperatures. 

  • Flat face blind flanges

Flat-face blind flanges have no protrusions. Hence, they are the best to use in a low-pressure environment. Metal gaskets help seal the flange and maintain a smooth appearance. Therefore, flat-face blind flanges are best for projects requiring a neat finish. 

Blind Flange Dimension

Blind flanges have the same pressure class and bolt holes as other flanges. However, these flags are thicker than the rest. You must know the critical measurements to pick the right size of a blind flange. Know the:

  • Outer bolt diameter
  • Bolt hole circle
  • Thickness 
  • Bolt hole diameter 

Most blind flanges are round. However, square blind flanges are available to use in hydraulic piping systems. The dimensions and specifications of the blind flange are specified under AWWA C207 and C228. Moreover, you can find them in ASME B16.5 and B16.47. 

Here are the most generic blind flange dimensions by type:

Blind Flange Style Available Size Range
B, D, E 4” – 72”
F, SF 4” – 48”
SA 2” – 8”
SB, SD, SE 2” – 72”
Sumitec @2023