Weld Neck Flange This flange is designed to be joined to a
piping system by butt welding. It is relatively expensive because
of its long neck, but is preferred for high stress applications.
The neck, or hub, transmits stresses to the pipe, reducing stress
concentrations at the base of the flange. The gradual transition
of thickness from the base of the hub to the wall thickness at the
butt weld provides important reinforcement of the flange.
The bore of the flange matches the bore of the pipe, reducing
turbulence and erosion.