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. flangesPressure Rating:- API 6BX-2000 PSI WP (With BX type Ring Gasket) Nominal Size B Flange Thickness T Hub Diameter J1 Groove Depth E Added Hub Thickness J4 263⁄ 4 30 4.97 5.28