What are the flange connection methods, what is the flange of each method

Flange connection methods can generally be divided into five types: flat welding, butt welding, socket welding, loose sleeves, and threads

Flat welding: only the outer layer is welded, and the inner layer is not needed; it is usually used in medium and low pressure pipelines, and the nominal pressure of the pipeline is lower than 2.5MPa. There are three types of sealing surfaces for flat welding flanges, namely smooth type, concave and convex type, and tenon and groove type. Among them, the smooth type is the most widely used, and it is affordable and cost-effective.

Butt welding: The inner and outer layers of the flange must be welded. Generally, it is used in medium and high pressure pipelines. The nominal pressure of the pipeline is between 0.25 and 2.5 MPa. The sealing surface of the butt welding flange connection method is concave and convex, and the installation is more complicated, so the labor cost, installation method and auxiliary material cost are relatively high.

Socket welding: Generally used in pipes with a nominal pressure of 10.0 MPa or less and a nominal diameter of 40 mm or less.

Loose sleeve: Generally used in pipelines with low pressure but corrosive medium, so this type of flange has strong corrosion resistance and the material is mostly stainless steel.

This connection is mainly used for the connection of cast iron pipes, rubber-lined pipes, non-ferrous metal pipes and flange valves. The connection of process equipment and flanges also uses flange connections.