What types of flanges are there? Does anyone know a more professional classification?

There are many types of flanges, which are mainly classified according to their nominal diameters (type A and B, that is, metric and imperial), nominal pressure, use structure, material, sealing surface form, and connection method (excluding diameter and pressure level). The types are: plate type flat welding flange (PL), neck welding flat flange (SO), neck welding flange (WN), integral flange (IF), socket welding flange (SW), thread Flange (Th), butt-welded ring loose-sleeve flange (PJ / PE), ring loose-sleeve flange (PJ / JR); according to the form of sealing surface: raised surface (RF), concave-convex surface (MFM), tongue and groove Surface (TG), full plane (FF), ring connection surface (RJ); flange covers are not included here; according to materials: cast iron flanges, cast steel, forging, Q235, stainless steel flanges, plastic flanges, etc.