api 5000*Tolerances and ring gaskets are according to API 6A. Materials for API 6A Type 6B 5000 psi(34.5 MPa) Weld Neck RTJ Flange, API 6A 6B Weld NeckAPI 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