Forge flanges are components that connect pipes together at the ends, featuring holes for bolts that tightly secure two flanges. They are sealed with gaskets. Forge flanged pipe fittings refer to pipe fittings equipped with forge flanges (also known as hubs or blanks). They can be cast (image pending), threaded, or welded. A flange joint consists of a pair of flanges, a gasket, and several bolts and nuts. The gasket is placed between the sealing surfaces of the flanges, and when the nuts are tightened, the gasket deforms and fills the irregularities on the sealing surface, ensuring a tight and leak-proof connection. Flange joints are removable. They can be categorized into vessel flanges and pipe flanges based on the connected parts. By structural type, there are integral flanges, loose flanges, and threaded flanges. Common integral flanges include flat weld flanges and socket weld flanges. Flat weld forge flanges have lower rigidity and are suitable for pressure p≤4MPa; socket weld flanges, also known as high-neck flanges, have greater rigidity and are used in high-pressure and high-temperature environments.