What is the difference between butt welding flange and flat welding flange?

　　Butt welding flange is the pipe diameter and wall thickness of the interface end are the same as the pipe to be welded, so it is welded as two pipes.

　　The flat welding flange is a concave which is slightly larger than the outer diameter of the pipe at the interface, and the pipe is inserted and welded inside.Butt welding has better welding performance and less corrosion.

　　Flat welding and butt welding are the welding methods for the connection of flange and pipeline. When welding flat welding flange, only one side welding is required, and the inner opening of the connection of pipeline and flange is not required. The welding and installation of butt welding flange need two sides welding of flange. Therefore, the flat welding flange is generally used for low and medium pressure pipes, and the butt welding flange is used for the connection of medium and high pressure pipes.

　　Generally, the butt welding flange is at least PN2.5MPa. The butt welding is used to reduce the stress concentration. Generally, the butt welding flange is also called nipple flange Therefore, the installation cost, labor cost and auxiliary material cost of butt welding flange should be high, because there is one more process.

　　Not all butt welding flanges need internal and external double-sided welding. There is no special requirement. Generally, they only need external welding. Haven't seen 1 / 2 "butt welding flange. ASME 304 stainless steel plate flange is better, because the pipe and flange are well aligned and vertical, and the pipe won't be inclined.