Welding flanges are non-deformable, provide good sealing, 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, ensuring the mating surface is not deformed by welding temperatures. They adopt a more complex trumpet-shaped structure, suitable for pipelines with significant fluctuations in pressure or temperature, as well as for high-temperature, high-pressure, and low-temperature pipelines. Generally used for pipe connections and valves with PN over 2.5 MPa; also used in pipelines transporting expensive, flammable, and explosive media.