Flange connection is one of the most widely used connection methods in pipeline connection construction. In our daily life, we often see it. For example, the natural gas pipelines, heating pipes, etc., are installed in the district, and many of them are flange connections.
Flange connection is to put two pipes, pipe fittings or equipment, first fixed on a flange plate, A detachable joint in which a flange pad is then added between the two flanges and a bolt is used to tighten the two flange plates tightly together.

Flange generally can be divided into the following five types: flat welding flange, welding flange welding, socket welding Flange, pine set flange, flange thread flange.

  1. Flat welding flange
    Flat welding flange is a kind of flange which is connected with container or pipe by fillet weld. It belongs to arbitrary flange. Flange ring has two kinds of neck and no neck. Flat welding neck flange is simple in structure, less material used in production, but its rigidity and tightness are not as good as the welding flange, which is widely used in the connection of low-pressure vessel and pipeline.
  2. Welding neck flange
    Generally refers to the welding neck flange and pipe transition, and pipe welding flange. Welding neck flange is not easy to deformation, sealing good characteristics, have the corresponding rigid and elastic. The distance between the weld and the joint surface is large. The joint will not be deformed because of the welding temperature, so it is widely used in pipeline welding.
    Welding neck flange is generally applicable to the pressure or temperature fluctuations in the pipeline, as well as high temperature, high pressure and low temperature pipeline, but also applies to transport expensive, flammable, explosive media on the pipeline.
  3. Socket welding flange
    Socket welding flange refers to the end of the pipe inserted in the flange ring ladder, the pipe end and outside the welding flange. The socket welding flange has good rigidity, small welding deformation and good sealing performance. It can be used in the pressure of 1.0 ~ 10.0 MPa.
  4. Loosened flange
    Loose flange is also called looper flange, flanged flange is the use of flanging, steel ring set in the end of the pipe, flange can be in the pipe end activities. The steel ring or flanging is the sealing surface, and the flange is to hold them tight. It can be seen that the loosened sleeve flange does not contact with the medium because it is blocked by the steel ring or flanging, and the disassembly and assembly of the pipeline can be more convenient.
    The loosened flange is suitable for the connection of steel, aluminum and other non-ferrous metals and stainless acid-resistant steel containers and corrosion resistant pipelines.
  5. Threaded flange
    The screw flange is to process the inner hole of the flange into the screw thread, and realize the connection with the pipe with screw thread. It is a non-welding flange. Compared with flat welding flange or welding neck flange, the threaded flange is easy to install and maintain, and can be used in some pipelines that are not allowed to be welded on site. The advantages are that welding is not required, and the additional torque produced on the cylinder or pipeline is very small when the flange is deformed. The shortcoming is the flange thickness is big, the cost is high, is suitable for the high-pressure pipeline connection. However, it is not recommended to use threaded flanges in case of sharp temperature changes in the pipeline.