Ring Joint Gaskets Type BX are manufactured in accordance with API 6A and are designed for use on pressurized systems up to 20,000 PSI. When correctly fitted, the style BX Ring Joint Gasket allows virtual surface-to-surface contact of the flange faces, which means that the Ring Joint Gasket is fully trapped on both the inner and outer diameters. All BX Ring Joint Gaskets incorporate a pressure balance hole to ensure equalization of pressure that may be trapped in the grooves.