The American standard flange is a part that connects the pipe and the pipe to each other, and is connected to the pipe end. American standard butt welding flanges are forged and cast in two ways. American standard butt welding flanges can be divided into necked American standard butt welded flanges and non-necked American standard butt welded flanges according to their neck conditions. The American standard butt welding flange consists of two flange plates plus flange gaskets, which are fastened together with bolts to complete the connection. There are holes on the American standard flanges, and the bolts make the two flanges tightly connected. The flanges are sealed with gaskets. ANSI B16.5 300lb sq.in Weld Neck Flange is your good choice.