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What Exactly Is a Flange?

May. 26, 2020

It is mentioned that many small friends of Français may not have a special understanding, and we do n’t see much in our daily life. In fact, Français was first proposed by an Englishman named Elkhart in 1809. At the same time, the flange casting method was also proposed, but it was not widely used for a considerable period of time. Until the early twentieth century, the flange was widely used in various mechanical equipment and pipe connections. A105 Flange factory introduces to you:


What is a flange?


Flanges are also called flange convex disks or convex disks. For those who are engaged in mechanical or engineering installations, flanges should be very familiar. It is a disc-shaped part and is generally used in pairs.

It is mainly used for parts such as pipes and valves, pipes and pipes, and pipes and equipment, which are connected to each other to play a sealing role. Because there are so many applications between this equipment and pipes, they will be The two planes are connected by bolts, and the connecting parts with sealing function are called flanges.

Generally, the flange has round holes for fixing. For example, when it is used at the pipe connection, a sealing ring is added between the two flanges, and then the bolt is used to fasten the connection. Different thicknesses and different bolts are used. The main materials used for flanges are carbon steel, stainless steel, and alloy steel.

Due to the important role played by flanges and good overall performance, flanges are widely used in chemical, petrochemical, fire protection, and drainage industries.

Flanges are widely used in the world as a kind of connector, which requires a unified standard. For example, pipeline flanges now mainly have two standard systems.

They are the European pipeline flange system, that is, the European pipeline flange system represented by German DIN (including Russia), and the American flange system represented by the American ANSI pipeline flange.

In addition, there is Japan's JIS pipeline flange system, China also has a steel pipeline flange system GB, but the main size is still based on the European system and the American system.


Types of flanges


The structure of the flange is relatively simple. It consists of three parts: upper and lower flanges, a gasket in the middle, and several bolts and nuts.

From the definition of the flange, we can know that there are many types, and the classification needs to be distinguished from different dimensions. For example, the flange can be divided according to the connection method, integral flange, flat welding flange, butt welding flange, Loose flanges, and threaded flanges, these are also common flanges.

Integral flange (IF) is generally used in pipelines with a higher pressure. It is a flange connection method and has a long neck. It is usually molded by one-time casting. The materials used are generally carbon steel and stainless steel.

Flat welded flanges are also called tower welded flanges. They are welded when connected to containers or pipelines. This flat welded flange is easy to assemble and inexpensive and is mainly used for pressure and The vibration is relatively small in the pipeline.

Butt welding flange is also called high neck flange. The biggest difference between butt welding flange and other flanges is that there is a protruding high neck. The protruding high neck wall thickness will gradually increase with the height of the pipe wall to be butted. As with the diameter, this will increase the strength of the flange. Butt-welded flanges are mainly used in places with large environmental changes, such as high temperature, high pressure, and low-temperature pipelines.

Loose flanges are also called loose flanges. These flanges are mostly used in non-ferrous metals and stainless steel pipes. The connection is also achieved by welding. Because they can be easily aligned with the bolt holes, they are often used in Large-diameter pipelines and joints that often need to be disassembled, but loose flanges have low-pressure resistance, so they can only be used for low-pressure pipeline connections.

The flange of the threaded flange has threads, which requires that the internally connected pipes also have external threads to achieve the connection. It is a non-welded flange, so it has the advantage of easy installation and disassembly compared to other welded flanges. It is not suitable to use threaded flanges in an environment with extremely high or low operating temperatures, because the threads are prone to leaks after thermal expansion and contraction.


Flange production process


As a kind of connecting and sealing parts, flanges will leak if there are quality problems in the production process, causing economic losses, environmental damage, and even safety accidents. Therefore, welding and production of flanges are very important.

At present, there are two main production processes of flanges: forging and casting. Let's take a look at these two main production processes and see what is different between them.


Carbon Steel Forged Flange


Forged flanges are beaten by the forging machine countless times so that the internal structure of the steel becomes tight, so the mechanical properties will be better and the strength will be higher. The forged flanges are mainly suitable for those pipelines with a higher pressure.

The first is to cut the cylindrical steel billet to a certain size, heat it to a certain temperature to make it thermoplastic, and place it on a cold heading to allow the forging machine to continuously beat the billet to make the billet more compact and mechanical. Better than the original billet.

The round holes on the flange are punched out from the steel billet by a punching machine. The formed rough flange is put into an electric furnace for heat treatment to increase the strength of the flange. Finally, the flange blank is cut and polished into a usable flange.

Carbon Steel Forged Flange

Carbon Steel Forged Flange


Casting Flange


Cast flanges have the characteristics of low manufacturing cost and high efficiency, and can produce flanges with more complex shapes. The cast flanges are mainly suitable for those pipelines with lower pressure.

Casting flanges is also a commonly used manufacturing process, which is to melt the metal into liquid molten steel, pour the molten steel into a preheated and constant temperature metal mold to form the shape of the flange. After the casting is naturally cooled for a period of time, Then use water to quickly cool down and demold, which can also increase the strength of the flange, and finally it can be used after polishing and anti-rust treatment.

Although small parts such as flanges are not noticeable in the entire product, pipeline or machinery, the role played by flanges is very important. In the future, with the development of flange materials and processes, the entire joint connection process can be guaranteed It is more precise and firm, ensuring people's safe and reliable use.