Detailed Explanation of Flange Connection Types And Applications

A flange, also known as a flange or flange, is a component that connects shafts to each other and is used for connecting pipe ends. It is also used as a flange on equipment inlet and outlet for connecting two devices. There are many types of flanges, and the following are some common classification methods:

1. Classified by connection method

a. Flat welding flange (PL): also known as lap flange, is a relatively simple flange composed of two steel plates welded together, usually used for connecting low-pressure pipelines. Flat welding flanges have a simple structure and require less material during production, but their rigidity and sealing are not as good as butt welding flanges. They are widely used for connecting medium and low pressure vessels and pipelines.

b. Welding flange (WN): composed of two welded steel plates or forgings, usually used for connecting medium and high pressure pipelines. Welding flanges have the characteristics of being less prone to deformation and having good sealing, as well as corresponding rigidity and elasticity. The distance between the welding junction and the joint surface is large, and the joint surface will not deform due to welding temperature, so it is currently widely used in pipeline welding. Welding flanges are generally suitable for pipelines with significant pressure or temperature fluctuations, as well as pipelines with high, high, and low temperatures. They are also suitable for pipelines that transport expensive, flammable, and explosive media.

c. Socket welding flange (SW): One end is welded to a steel pipe, and the other end is connected with bolts. It is commonly used in pipelines with PN ≤ 10.0MPa and DN ≤ 40. Socket welding flanges have good rigidity, minimal welding deformation, and good sealing performance.

d. Threaded flange (Th): The inner hole of the flange is machined into pipe threads and connected to threaded pipes. It is a non welded flange suitable for situations where welding is not allowed on site. Threaded flanges have the characteristics of easy installation and maintenance, but they have a large flange thickness and high cost, making them suitable for connecting high-pressure pipelines. Under conditions of rapid temperature changes in pipelines, it is not recommended to use threaded flanges to avoid leakage.

e. Loose flange: including butt welded ring loose flange and flat welded ring loose flange, mainly used to save materials or facilitate construction. Its structure allows different materials to be used for the flange and pipe parts. Loose flanges can be used without contact with the medium, making it easy to disassemble and assemble pipelines.

2. Classified by Material

a. Carbon steel flange: made of carbon steel material, usually used for general industrial pipeline connections.

b. Stainless steel flange: made of stainless steel material, suitable for connecting corrosive medium pipelines.

c. Alloy steel flange: made of alloy steel material with sufficient strength, but not easy to weld or with poor welding performance, suitable for connecting high temperature and high pressure pipelines.

d. Copper flange: made of copper material, usually used for connecting water supply pipelines.

e. Plastic flange: made of plastic material, suitable for connecting plastic pipes.

3. Classify by sealing surface form

a. RF: The most common form of sealing surface, suitable for most situations.

b. Concave convex surface (MFM): suitable for situations with slightly higher pressure.

c. Mortise and tenon surface (TG): suitable for flammable, explosive, toxic media, and high-pressure environments.

d. Full plane (FF): Suitable for situations with low pressure and non-toxic media.

e. Ring connection surface (RJ): used for specific high-pressure sealing applications.

4. Classify according to other standards

Flanges can also be classified in various ways such as diameter, pressure, and purpose. For example, it can be divided into large-diameter flanges and small-diameter flanges according to their diameter size; According to pressure levels, it can be divided into low-pressure flanges, medium pressure flanges, and high-pressure flanges.

In summary, there are many types of flanges, each with its specific application scenarios and advantages. When selecting flanges, it is necessary to comprehensively consider factors such as specific engineering requirements, pipeline parameters, and medium characteristics.