Access assemblies includes an instrument valve housing and a valve assembly disposed within the cavity of the instrument valve housing. The valve assembly includes a guard assembly, a seal assembly disposed adjacent to the guard assembly, and a centering mechanism for maintaining the seal assembly and guard assembly centered within a cavity of the instrument valve. In embodiments, the seal assembly includes a plurality of seal sections that are movable from an unfolded configuration to folded configuration in which the seal assembly forms a hexagonal member defining an opening to facilitate sealed passage of a surgical instrument. The seal sections may include a tapered inner edge for engaging a surgical instrument inserted through the instrument valve housing.
