1) Standard: ANSI, JIS, DIN, BS
2) Size: DN15 - DN1000

3) Type: Flat Face Flanges, Slip On, Welding Neck, Blind, Threaded,etc. 

 Water , Oil, Gas, Industrial Using 

4):Materials: Carbon Steel & Stainless steel
Flanges are the connectors used in process piping to connect pipe to tees,   elbows, valves, pumps and whatever other equipment may be necessary.