Flange connection method

The flange connection methods can generally be divided into five types: flat welding, butt welding, socket welding, loose fitting, and threading.
Below is a detailed explanation of the first four types:
1. Flat welding: only weld the outer layer, no need to weld the inner layer; Generally used in medium and low pressure pipelines, the nominal pressure of the pipeline should be lower than 0.25MPa. There are three types of sealing surfaces for flat welding flanges, namely smooth type, concave convex type, and mortise and tenon type. Among them, the smooth type is the most widely used and has an affordable price and high cost-effectiveness.
2. Butt welding: Both the inner and outer layers of the flange need to be welded, which is generally 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 welded flange connection method is concave convex, and the installation is relatively complex, so the labor cost, installation cost, and auxiliary material cost are relatively high.
3. Socket welding: generally used in pipelines with nominal pressure less than or equal to 10.0MPa and nominal diameter less than or equal to 40mm.
4. Loose sleeve: Generally used in pipelines with low pressure but corrosive media, this type of flange has strong corrosion resistance and is mainly made of stainless steel material.
This type of connection is mainly used for connecting cast iron pipes, lined rubber pipes, non-ferrous metal pipes, and flange valves. The connection between process equipment and flanges also uses flange connections.