Difference analysis between butt welding flange and special-shaped flange The sealing surface of butt welding flange can be made into three types: smooth type, concave-convex type and tongue-and-groove type. The application of smooth butt welding flange is large. Generally, it is mostly used when the medium conditions are relatively moderate, such as low-pressure unpurified compressed air and low-pressure circulating water. Its advantage is that the price is relatively cheap. Butt welding flanges are suitable for pipelines with large fluctuations in pressure or temperature or pipelines with high temperature, high pressure and low temperature, and are also used for pipelines that transport expensive, flammable and explosive media. The welding method used when connecting the flange and the pipeline of the butt welding flange is butt welding. The welding seam is similar to the welding of pipelines and pipelines. Generally, argon arc welding is used for the bottom of the small pipe diameter, and the cover surface is manually welded. Only use double-sided welding.