api 5000Api 6a Wn Flanges applications including pressure classes – 720 psi and 960 psi, the API specified no changes to the ASA B16.5 Standard, using the 300 lb. and 400 lb. flangesAPI 6A flanges of class 5000 and below are often made of A105 carbon steel with a minimum yield strength of 45K, while API 6BX flanges of class 10000