Butt welding flange is not easy to deform, has good sealing, and is widely used. It is suitable for pipelines with significant fluctuations in pressure or temperature, as well as high-temperature, high-pressure, and low-temperature pipelines. The advantage is that it is relatively cheap, with a nominal pressure not exceeding 2.5MPa; It is also used on pipelines that transport expensive, flammable, and explosive media, with a nominal pressure of around PN16MPa.