A flat welding flange is a type of flange that connects to a vessel or pipe using angular welding, classified as a non-rising flange, with both necked and neckless designs for the flange ring. The structure of a flat welding flange is simple and requires less material during manufacturing, yet it lacks the rigidity and sealing performance of a welding neck flange. It is widely used for connecting medium and low-pressure vessels and pipelines.