BX-Gaskets have been designed for higher-pressure rated systems, 5,000 lbs. to 20,000 lbs. Pitch diameters on BX gaskets are slightly larger than the pitch diameter of the flange forcing a primary seal on its outside angles and a secondary seal with its inside angles as the flange is bolted down to respective torque settings. Gaskets that have been torqued initiating a metal-to-metal seal should be discarded and not reused. BX Series can only be used with 6BX flanges and 16BX hubs.