api 5000API 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 10000API 5k Flange API 5000 API 10k Flange API 10000 API 15k Flange API 15000 View API ring joint flange pressure rating, Ramesh Group produces class 3000 To 10000 in forging methods.