Flat welding steel flange: it is suitable for steel pipe connection with nominal pressure less than 2.5MPa. The sealing surface of flat welding flange can be made into smooth type, concave convex type and tenon groove type. Smooth flat welding flange is the most widely used. It is mostly used under mild medium conditions, such as low-pressure non purified compressed air and low-pressure circulating water. Its advantage is that the price is relatively cheap. Butt welding flange is suitable for pipelines with large fluctuation of pressure or temperature, or pipelines with high temperature, high pressure and low temperature. It is also used for pipelines conveying expensive, flammable and explosive media. Butt welding flange is not easy to deform, good sealing, widely used, the nominal pressure PN is about 16MPa.

Butt welding flange refers to the flange with neck and pipe transition and butt welding with pipe.

Butt welding steel flange: it is used for butt welding of flange and pipe. It has reasonable structure, high strength and rigidity, can withstand high temperature and high pressure, repeated bending and temperature fluctuation, and has reliable sealing performance. The butt welding flange with nominal pressure of 0.25 ~ 2.5MPa adopts concave convex sealing surface.

Flat welding and butt welding are the welding methods when the flange and pipeline are connected. When the flat welding flange is welded, only one side welding is needed, and the inner mouth of the pipeline and flange connection does not need to be welded. The welding installation of butt welding flange requires double-sided welding of the flange.

Butt welding is adopted for the connection of flange and pipeline of butt welding flange. The welding seam is similar to that of pipeline and pipeline. Generally, argon arc welding is used for backing for small pipe diameter, manual welding is used for covering, and double-sided welding is used for large pipe diameter.