API 6A Blind flange is a flange system from USA, which have flange type including Welding neck Flanges, blind Flange.

Type 6B flanges are of the ring joint type and are not designed for face-to-face make-up. The connection make-up bolting force reacts on the metallic ring gasket. Type 6B flanges are of through bolted or studded design. Dimensions for 6B flanges blind type shall conform to Table 36, Table 37 & Table 38 with reference to figure no. 8 on pg. no. 108 of API 6A (19 th Edition, July 2004) as applicable.

Type 6BX flanges are of the ring joint type and designed with a raised face. Depending on the tolerances, the connection make-up bolting force may react on the raised face of the flange when the gasket has been properly seated. This support prevents damage to the flange or gasket from excessive bolt torque. Therefore, one of the flanges in 6 BX connection shall have a raised face. Type 6BX flanges are of through bolted or studded design. Face-to-face contact is not necessary for the proper functioning of the 6BX flange. Dimensions for 6BX flanges blind type shall conform to Table 46 of API 6A (19 th Edition, July 2004) as applicable.