The casting and forging flanges have advantages that the blanks of them have accurate shape, size and low costs and only need simple process. But forging flanges have manufacturing defects such as blowholes, cracks, etc and have not very smooth internal organization streamline. The obvious advantages of forging flanges are that they can be forged in various shapes and they have low costs. . Forging flanges generally have lower carbon content than the casting flanges and are not easy to rust. They have smooth streamline, uniform internal organization, and better mechanical performance than that of casting flanges. There are no defects, such as blowholes and cracks existing in the casting flanges. Forging flanges are able to withstand higher shear and drawing forces than casting flanges. However, if adopting improper forging process, it will also cause appearance of large, uneven grains and solidification cracking phenomenon, resulting in higher cost than the casting flanges. . http://www.kobsindia.in/super-duplex-socket-weld-flange.html