Weldneck Flanges - These are the most common type of flange used for high pressure applications. They are recognized by their long tapered hub. The hub provides an important reinforcement to the flange itself and acts to reduce rotation of the flange at bolt-up. The smooth transition between the flange and the hub combined with the strength of the butt weld joint, allows the flange to be used in extreme conditions of cyclic loading, bending and temperature fluctuations.

http://www.welding-units.co.uk/Flanges/about_flanges.htm

TIPOS DE BRIDAS Y CARACTERÍSTICAS:
Brida con cuello para soldar es utilizada con el fin de minimizar el numero de soldaduras en pequeñas piezas a la vez que contribuya a contrarrestar la corrosión en la junta.
http://www.arqhys.com/tuberias-bridas.html