Flat welding flange refers to a flange connected with a container or pipeline by fillet welding. It is an arbitrary flange. According to the integrity degree of the flange ring and the straight cylinder section during the design, check the integral or loose flange respectively.

There are two types of flange ring with neck and without neck. Compared with the neck butt welding flange, the flat welding flange has a simple structure and saves materials, but the rigidity and sealing performance are not as good as the neck butt welding flange. Flat welding flanges are widely used in the connection of medium and low pressure vessels and pipelines.