These flat welding flanges are ASME B16.5 flat welding flange, ASME B16.47 flat welding flange, DIN 2634 flat welding flange, DIN 2635 flat welding flange, DIN 2630 flat welding flange, DIN 2636 flat welding method Flanges, DIN 2631 flat welding flanges, DIN 2637 flat welding flanges, etc. Flanges are parts that connect pipes to each other and are connected to pipe ends. There are holes on the flange, and bolts make the two flanges tightly connected. Gaskets are used to seal between flanges. Flat welding flanges are suitable for steel pipe connections with a nominal pressure not exceeding 2.5MPa. The sealing surfaces of flat welding flanges can be made of smooth, concave-convex and tongue-and-groove types.