Weld neck flanges are less prone to deformation, provide good sealing, and have a wide range of applications. They meet the requirements for both rigidity and elasticity, featuring a reasonable weld thinning transition. The weld joint is spaced far from the mating surface, protecting it from 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 for high-temperature, high-pressure, and low-temperature pipelines. Generally used for connections on pipelines and valves with PN ratings above 2.5 MPa; also used in pipelines transporting expensive, flammable, and explosive media.