The difference between flat welded flange with neck and butt welded flange

　　Butt-welded neck flange is the same diameter and wall thickness of the joint end as the pipe to be welded, and it is welded in the same way as the two pipes.

　　Flat welded neck flange is a concave platform with inner hole machined slightly larger than the outside diameter of the pipe, and the pipe is inserted into the inside to weld.

　　Flat welding and butt welding refer to the welding mode when flange and pipeline are connected. ANSI B16.5 150LBS Carbon Steel Weld Neck Flanges only needs one side welding without the internal opening of flange and pipeline connection. Weld neck flanges and installation of butt welding flange needs double side welding. Therefore, flat Weld neck flanges is generally used for low and medium pressure pipelines, butt weld neck flanges is used for the connection of medium and high pressure pipelines, butt weld neck flanges is generally at least PN2.5 MPa, butt welding is used to reduce stress concentration, the common butt welding flange is also called high neck flange. Therefore, the installation cost, labor cost and auxiliary material cost of butt weld neck flanges are high, because there is more than one process