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 transmits stresses to the pipe, reducing stress concentrations at the base of the Flange. The gradual transition of thickness from the base to the neck 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.