Large-diameter flanges are used for butt welding between flanges and pipes, primarily employed in welding technology. They exhibit excellent performance characteristics and reliability, featuring a rational structure with high strength and stiffness. They can withstand high temperatures, high pressures, repeated bending, and temperature fluctuations, ensuring reliable sealing. Rolled flanges with a nominal pressure of 0.25 to 2.5 MPa utilize a convex-concave sealing surface. Rolled flanges are suitable for specific environmental conditions, and their application must be determined based on specific circumstances to ensure their specific usage value and performance, capable of withstanding high temperatures and pressures.