Flat Weld Flange refers to a flange that is connected to a vessel or pipeline with a fillet weld. It belongs to the general type of flanges. During design, the integrity of the connection between the flange ring and the straight tube section determines whether it is to be checked as a solid or loose flange. Flange rings come in two types: with neck and without neck. Compared to neck welding flanges, flat weld flanges have a simpler structure, use less material, but are not as rigid or sealing as neck welding flanges. Flat weld flanges are widely used in the connection of medium and low-pressure vessels and pipelines.