An access assembly includes an instrument valve housing defining a cavity, and a valve assembly. The valve assembly includes a flange seal member, a seal assembly, a centering mechanism, and a retainer frame assembly. The flange seal member includes an arcuate portion configured to adjustably engage first and second surfaces of the instrument valve housing in a sealing relation. The centering mechanism is configured to bias the valve assembly towards a generally centered position within the cavity. The centering mechanism includes a plurality of coils including inner coil portions operatively secured with the seal assembly, and outer coil portions configured to engage the first surface of the instrument valve housing. The retainer frame assembly includes first and second members. The inner coil portion of the centering mechanism is disposed between seal assembly and the second member of the retainer frame assembly.