Welding flanges are non-deformable, provide excellent sealing, and have wide applications. They meet the requirements for both rigidity and elasticity with a reasonable transition to the thinning part. The weld joint is far from the mating surface, preventing deformation due to welding temperatures. They feature a more complex trumpet-shaped structure, suitable for pipelines subject to significant fluctuations in pressure or temperature, as well as for high-temperature, high-pressure, and low-temperature pipelines. Typically used for pipeline and valve connections with PN greater than 2.5 MPa; also used in pipelines for transporting expensive, flammable, and explosive media.