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Classification and distinction of flanges


Flange connection is one of the most widely used connection methods in pipeline connection construction, and we will often see it in daily life.

For example, the exposed natural gas pipelines and heating pipelines in the community are used by flange connections.

Flange connection is a kind of removable joint that first fixes two pipes, pipe fittings or equipment on a flange plate, and then adds flange pads between the two flanges, and finally tightens the two flanges with bolts to make them tightly combined.

Classification and distinction of flanges

flat welding flange

Flat welding flange(SO)

Flat welding flange refers to a kind of flange connected with fillet weld with the container or pipeline, which is an arbitrary flange, and the flange ring has two kinds of neck and no neck. Flat welding flange has a simple structure and less materials used in production, but its rigidity and sealing are not as good as butt welding flanges, and it is widely used in the connection of medium and low pressure vessels and pipelines.

Butt welding flange(WN)

Butt welding flange generally refers to a flange with a neck and a round pipe transition and connected to the pipe butt weld. Butt welding flange has the characteristics of not easy deformation, good sealing, and corresponding rigidity and elasticity. The weld is far from the joint surface, and the joint surface will not be deformed due to welding temperature, so it is widely used in pipe welding.

WN flange

Butt welding flanges are generally suitable for pipelines with large fluctuations in pressure or temperature, as well as high-temperature, high-pressure and low-temperature pipelines, and are also suitable for pipelines transporting expensive, flammable and explosive media.

socket welding flange

Socket welding flange(SW)

Socket welding flange refers to the flange that is inserted into the flange ring step at the end of the pipe and welded at the end and outside of the pipe. The socket welding flange has good rigidity, small welding deformation and good sealing, and can be used for occasions with a pressure of 1.0~10.0MPa.

Loose flange(LJ)

Loose flange is also called looper flange, loose flange is the use of flange, steel ring, etc. to put the flange on the pipe end, the flange can be active on the pipe end.

loose flange

Steel rings or flanges are the sealing surfaces, and the role of the flanges is to press them. It can be seen that because it is blocked by the steel ring or flange, the loose flange does not contact with the medium, and the pipeline can be disassembled and installed more conveniently.

Loose flange is suitable for the connection and corrosion-resistant pipelines of non-ferrous metals such as steel and aluminum and stainless acid-resistant steel containers.

Threaded flange

Threaded flange(PT)

Threaded flange is a kind of non-welded flange that processes the inner hole of the flange into a thread and connects it with the threaded pipe. Compared with flat welding flanges or butt welding flanges, threaded flanges are easy to install and maintain, and can be used on pipelines that are not allowed to be welded on some sites.

The advantage is that no welding is required, and the additional torque generated on the cylinder or pipe when the flange is deformed is small. The disadvantage is that the flange thickness is large, the cost is high, and it is suitable for the connection of high-pressure pipelines. However, under the condition of sharp temperature changes in the pipeline, it is not recommended to use threaded flanges to avoid leakage.

Classification and distinction of flanges

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