What is blind flange?

What is blind flange?

A blind flange is a round plate which has all of the relevant blowholes except center hole, and because of this feature the blind flange is usually 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.

 

Without the blind flange it would be difficult to perform maintenance or repairs on a pipeline. The flow would need to be shut off at the nearest valve, which could be miles away from the repair area. Valves are also very expensive and are prone to sticking. The blind flange is a much more cost efficient way of sealing a pipe.

 

Blind Flanges are commonly used in petrochemical, pipe engineering, public services and water treatment etc.

A blind flange (BF) is a piping component for covering or closing the end of a pipe, valve, vessel or tank. When used at the end of a pipe, vessel or tank, it provides an easy open access for further extension of the pipe. Because the blind flange’s sole purpose is to contain the pressure of the pipe, it (and its bolts) are stressed more than any other flange.

 

Blind flanges, abbreviated as BV, are commonly used in any industries that utilize piping. They are available in all face types (RTJ, Raised and Flat Face) at all pressure ratings. A blind can be inserted between two flanges to block flow but this isn’t good practice in most piping. When trying to block flow temporarily in a pipe, the designer should use a spectacle blind instead.

 

A blind flange would be used at the end of a valve to ensure the accidental opening of a valve will not cause an escape of the process fluid.

 

When designing a piping system for expansion, a blind flange can be used to allow for bolting on piping when the expansion is completed. This design allows for expansion or continuation of the pipeline by simply adding onto the final flange. If used on a manifold in dirty service a blind flange can be used by the operations and maintenance staff to clean out or inspect the piping during a shutdown.

 

When placing a blind flange on a vessel man way, consider how it will be removed. It may require the addition of a lifting eye for a crane or a specially designed davit to hold the flange in place after the bolts are removed. Care should be taken in that the davit must be designed to be able to hold the entire weight of the flange.

 

A blind flange is a solid disk used to block off a pipeline or to create a stop. It is machined in the same manner as a regular flange with the mounting holes around the perimeter and the gasket sealing rings machined into the mating surface. The difference is that a blind flange has no opening to allow fluid to pass through. The blind flange can be inserted between two open flanges and used to block off the flow of liquid through a pipeline.

 

Often a blind flange is inserted into a pipeline when a repair is required further up the line. This allows the flanges down stream to be disconnected without fear of losing liquid. Many times this type of blockade is used when adding another line onto an existing pipeline or when a new valve is being added. This blockade is also used to shut down a line when it is no longer needed.

 

Without the blind flange it would be difficult to perform maintenance or repairs on a pipeline. The flow would need to be shut off at the nearest valve, which could be miles away from the repair area. Valves are also very expensive and are prone to sticking. The blind flange is a much more cost efficient way of sealing a pipe.

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