Seeking answers regarding control valve knowledge

Raised face of valve flange connection – abbreviated as (RF). Flat face of valve flange – full face, abbreviated as (FF). Female face of valve flange – abbreviated as (FMF)； Valve flange male face – abbreviation (MF) ； Valve male-female surface – abbreviation (MFM). Butt welding of valves – abbreviation (BW). Socket welding of valves – abbreviation (SW). I’m not sure about the other terms; I couldn’t find any information on them either

RF convex connection, RJ ring connection surface; the other two have not been seen.

RF stands for raised face, which means a protruding surface; it is sometimes even more protruding than a bossed surface. It must never be written as convex surface! What is written on the 3rd floor is incorrect. @LBT10987 RJ: Ring joint refers to a circular connection surface; it is sometimes also written as RTJ: Ring Tenon Joint, which denotes a circular tenon-and-socket connection. This is the same as the RJ notation – there is no difference between them. MFM: connection between convex and concave surfaces; M: male, which refers to the convex surface; FM: female, which refers to the concave surface. Any other notation is incorrect. There is no notation for MF. RE: The original poster made a mistake; flanges are not written this way. Suspected to be RF? Rc: It refers to a threaded connection; RC denotes internal threads. It is generally required that the diaphragm head of control valves be equipped with RC threaded connectors. Corresponding to RC is R, and R represents an external thread. Rc is the imperial sealed pipe thread. It is best to check the flange standards: HG/T20592~20635-2009, which are divided into the European system and the American system, and they differ from each other.