Welding flanges are resistant to deformation, provide a good seal, and are widely used. They meet the requirements for both rigidity and elasticity and feature a reasonable welding thinning transition. The weld joint is far from the mating surface, protecting it from deformation caused by welding temperatures. They adopt a more complex trumpet-shaped structure, suitable for pipelines experiencing significant fluctuations in pressure or temperature, as well as for high-temperature, high-pressure, and low-temperature pipelines. They are commonly used for connecting pipelines and valves with a PN value greater than 2.5 MPa; they are also used in pipelines transporting expensive, flammable, and explosive media.