The flange type or structural type is mainly divided according to the way the flange is connected to the pipe, and can be divided into: integral flange, threaded flange with neck, welding flange with neck, flat welding flange with neck, socket welding flange with neck, plate flat welding flange, A-type welding ring plate loose sleeve flange, B-type welding ring plate loose sleeve flange, flat welding ring plate loose sleeve flange, pipe end flange loose sleeve flange (A type) Flanging short joint plate loose flange (B-type) and flange cover (also known as blind flange), etc.

The overall flange is mainly designed for the flanges at the inlet and outlet of mechanical equipment such as pumps and valves, specifically used to connect with the flange at the pipe. These inlet and outlet flanges are usually integrated with the casing of mechanical equipment as a part of the equipment. The flange is usually cast together with the shell of the equipment, with a few being cast (such as end flanges on forged steel valves).

The threaded flange is a non welded flange that processes the inner hole of the flange into a pipe thread and is connected to a threaded pipe. Compared with welded flanges, threaded flanges have the characteristics of easy installation and maintenance, and can be used on some pipelines that are not allowed to be welded on site. Alloy steel flanges have sufficient strength, but are not easy to weld or have poor welding performance. Threaded flanges can also be used. However, it is recommended not to use threaded flanges when the pipeline temperature changes sharply or when the temperature is above 260 ℃ or below -45 ℃ to avoid leakage.

Butt welding flange, also known as high neck flange, differs from other flanges in that there is a long and inclined high neck from the welding point between the flange and the pipe to the flange plate. The wall thickness of this high neck gradually transitions to the pipe wall thickness along the height direction, improving the discontinuity of stress and thus increasing the strength of the flange. Butt welding flanges are mainly used in situations where the working conditions are relatively harsh. For example, in situations where pipeline thermal expansion or other loads cause significant stress or repeated stress changes at the flange; Pipelines with significant fluctuations in pressure and temperature, or pipelines applied under high, high, and low temperature conditions.

Flat welded titanium flange, also known as lap welded flange. The connection between flat welding flange and pipe is achieved by inserting the pipe into the flange hole at an appropriate position before welding. Its advantage is that it is easier to align during welding and assembly, and the price is cheap, which has been widely used.