Butt welding flange with neck refers to a kind of flange with taper neck and butt welding with cylinder or pipeline. It belongs to integral flange. Because of the excessive structure and butt welding connection of the taper neck, the strength and rigidity of the flange are strengthened, the butt welding flange is not easy to deform, well sealed and widely used.

      The sealing surface forms are: RF, FM, m, t, G, FF and RJ.