Welding flanges are resistant to deformation, provide a good seal, and have a wide range of applications. They meet the requirements for both rigidity and elasticity and feature a reasonable transition of weld thinning. The weld joint is far from the mating surface, preventing deformation due to welding temperatures. They adopt a relatively complex trumpet-shaped structure, suitable for pipelines subject to significant fluctuations in pressure or temperature, as well as high-temperature, high-pressure, and low-temperature pipelines. They are generally used for pipe and valve connections with PN ratings above 2.5 MPa; they are also used in pipelines for transporting expensive, flammable, and explosive media.